https://ybfwrb.org/yakipedia/api.php?action=feedcontributions&feedformat=atom&user=JyeagerYakipedia - User contributions [en]2026-06-13T13:55:41ZUser contributionsMediaWiki 1.44.0https://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1719Water stargrass2025-09-30T03:00:29Z<p>Jyeager: /* Digital Resources */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River storage reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for stargrass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticeable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operators to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* Pelly and others produced a [https://ybfwrb.org/wp-content/uploads/2025/09/WSG-Harvesting-Assessment_2024_rev-1.pdf 2024 report] on water stargrass removal on dissolved oxygen, temperature, and water velocity in the Lower Yakima River.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include:<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) and partners have researched and piloted several techniques to control water stargrass in the Lower Yakima River. Starting with the [https://ybfwrb.org/wp-content/uploads/2025/09/WSGRecommendations_BCD_Rev-3.pdf 2022 water stargrass recommendation report] and followed by the Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD and Mid-Columbia Fisheries completed an [https://ybfwrb.org/wp-content/uploads/2025/09/7_WSG-Emergency-Drought_Final.pdf emergency drought response plan] for control of water stargrass in low water years. <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf white paper] that provides a good overview of stargrass control strategies and efforts in the Lower Yakima River, the coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. The Benton Conservation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/FY24-Harvesting-Operations_Final_240222.pdf report] on water stargrass mechanical harvest operations from 2021-2023. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodging it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stargrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stargrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video]<br />
<br />
UW Burke Herbarium - [https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Heteranthera%20dubia Water Stargrass page]<br />
<br />
[https://drive.google.com/drive/folders/1OEBjOyEHErkdt1ead5XO2blkzYJb1DvR?usp=drive_link Water Stargrass Coalition Pictures] Includes an assortment of pictures ranging from hand-pulling efforts to conditions in the Lower Yakima River. <br />
<br />
Aaron Pelly's [https://ybfwrb.org/wp-content/uploads/2025/09/SFS-2025_Presentation_Pelly.pdf Water Stargrass presentation] at the Society for Freshwater Science Annual Meeting in 2025. <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1716Water stargrass2025-09-26T21:16:35Z<p>Jyeager: /* Digital Resources */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River storage reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for stargrass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticeable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operators to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* Pelly and others produced a [https://ybfwrb.org/wp-content/uploads/2025/09/WSG-Harvesting-Assessment_2024_rev-1.pdf 2024 report] on water stargrass removal on dissolved oxygen, temperature, and water velocity in the Lower Yakima River.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include:<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) and partners have researched and piloted several techniques to control water stargrass in the Lower Yakima River. Starting with the [https://ybfwrb.org/wp-content/uploads/2025/09/WSGRecommendations_BCD_Rev-3.pdf 2022 water stargrass recommendation report] and followed by the Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD and Mid-Columbia Fisheries completed an [https://ybfwrb.org/wp-content/uploads/2025/09/7_WSG-Emergency-Drought_Final.pdf emergency drought response plan] for control of water stargrass in low water years. <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf white paper] that provides a good overview of stargrass control strategies and efforts in the Lower Yakima River, the coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. The Benton Conservation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/FY24-Harvesting-Operations_Final_240222.pdf report] on water stargrass mechanical harvest operations from 2021-2023. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodging it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stargrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stargrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video]<br />
<br />
UW Burke Herbarium - [https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Heteranthera%20dubia Water Stargrass page]<br />
<br />
[https://drive.google.com/drive/folders/1OEBjOyEHErkdt1ead5XO2blkzYJb1DvR?usp=drive_link Water Stargrass Coalition Pictures] Includes an assortment of pictures ranging from hand-pulling efforts to conditions in the Lower Yakima River. <br />
<br />
Aaron Pelly's Water Stargrass presentation at the Society for Freshwater Science Annual Meeting in 2025. <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1715Lower Yakima River2025-09-26T21:11:08Z<p>Jyeager: /* Fish Use */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, tributary streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749 cfs. At Chandler Pump Station, the 416 cfs used to drive the hydraulic pumps is returned to the Yakima River at river mile 35.8<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''Yakima River Basin Water Enhancement Program (YRBWEP) and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during non-prorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR (YRPW) Prosser Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A 9-foot-high concrete weir diversion dam on the Yakima River near Prosser. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500 cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1714Yakima Basin Key References2025-09-26T21:10:15Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br /><br /><br />
* The 1945 District Court of Eastern Washington Consent Decree. [https://ybfwrb.org/wp-content/uploads/2025/09/WASupremeCourt_1945ConsentDecree.pdf See PDF]<br /><br /><br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br /><br /><br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br /><br /><br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br /><br /><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br /><br /><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1713Yakima Basin Key References2025-09-26T21:10:00Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br /><br />
* The 1945 District Court of Eastern Washington Consent Decree. [https://ybfwrb.org/wp-content/uploads/2025/09/WASupremeCourt_1945ConsentDecree.pdf See PDF]<br /><br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br /><br /><br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br /><br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br /><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br /><br /><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1712Yakima Basin Key References2025-09-26T21:09:16Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br /><br />
* The 1945 District Court of Eastern Washington Consent Decree. [https://ybfwrb.org/wp-content/uploads/2025/09/WASupremeCourt_1945ConsentDecree.pdf See PDF]<br /><br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br /><br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br /><br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br /><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br /><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1711Yakima Basin Key References2025-09-26T21:08:56Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br /><br />
*<br />
* The 1945 District Court of Eastern Washington Consent Decree. [https://ybfwrb.org/wp-content/uploads/2025/09/WASupremeCourt_1945ConsentDecree.pdf See PDF]<br /><br />
*<br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br /><br />
*<br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br /><br />
*<br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br /><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br /><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1710Yakima Basin Key References2025-09-26T21:08:33Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br /><br />
* The 1945 District Court of Eastern Washington Consent Decree. [https://ybfwrb.org/wp-content/uploads/2025/09/WASupremeCourt_1945ConsentDecree.pdf See PDF]<br /><br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br /><br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br /><br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br /><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br /><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1709Yakima Basin Key References2025-09-26T21:08:06Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br /><br />
<br />
* The 1945 District Court of Eastern Washington Consent Decree. [https://ybfwrb.org/wp-content/uploads/2025/09/WASupremeCourt_1945ConsentDecree.pdf See PDF]<br /><br />
<br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br /><br /><br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br /><br /><br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br /><br /><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br /><br /><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1708Yakima Basin Key References2025-09-26T21:07:02Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br /><br />
<br />
* The 1945 District Court of Eastern Washington Consent Decree. [https://ybfwrb.org/wp-content/uploads/2025/09/WASupremeCourt_1945ConsentDecree.pdf See PDF]<br /><br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br /><br /><br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br /><br /><br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br /><br /><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br /><br /><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1707Yakima Basin Key References2025-09-26T21:06:33Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br />
<br />
* The 1945 District Court of Eastern Washington Consent Decree. [https://ybfwrb.org/wp-content/uploads/2025/09/WASupremeCourt_1945ConsentDecree.pdf See PDF]<br /><br /><br /><br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br /><br /><br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br /><br /><br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br /><br /><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br /><br /><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1706Yakima Basin Key References2025-09-26T21:06:09Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br />
<br />
* The 1945 District Court of Eastern Washington Consent Decree. [https://ybfwrb.org/wp-content/uploads/2025/09/WASupremeCourt_1945ConsentDecree.pdf See PDF]<br /><br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br /><br /><br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br /><br /><br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br /><br /><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br /><br /><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1700Lower Yakima River2025-09-12T17:24:26Z<p>Jyeager: /* Facilities */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, tributary streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749 cfs. At Chandler Pump Station, the 416 cfs used to drive the hydraulic pumps is returned to the Yakima River at river mile 35.8<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''Yakima River Basin Water Enhancement Program (YRBWEP) and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during non-prorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR (YRPW) Prosser Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A 9-foot-high concrete weir diversion dam on the Yakima River near Prosser. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500 cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1699Lower Yakima River2025-09-12T17:04:03Z<p>Jyeager: /* Facilities */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, tributary streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749 cfs. At Chandler Pump Station, the 416 cfs used to drive the hydraulic pumps is returned to the Yakima River at river mile 35.8<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''Yakima River Basin Water Enhancement Program (YRBWEP) and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during non-prorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR (YRPW) Prosser Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A 9-foot-high concrete weir diversion dam on the Yakima River near Prosser. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1698Lower Yakima River2025-09-12T17:02:57Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, tributary streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749 cfs. At Chandler Pump Station, the 416 cfs used to drive the hydraulic pumps is returned to the Yakima River at river mile 35.8<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''Yakima River Basin Water Enhancement Program (YRBWEP) and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during non-prorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR (YRPW) Prosser Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1697Lower Yakima River2025-09-12T17:01:35Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, tributary streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749 cfs. At Chandler Pump Station, the 416 cfs used to drive the hydraulic pumps is returned to the Yakima River at river mile 35.8<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during non-prorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR (YRPW) Prosser Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1696Lower Yakima River2025-09-12T16:58:59Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, tributary streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749 cfs. At Chandler Pump Station, the 416 cfs used to drive the hydraulic pumps is returned to the Yakima River at river mile 35.8<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR (YRPW) Prosser Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1695Lower Yakima River2025-09-12T16:56:34Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, tributary streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749 cfs. At Chandler Pump Station, the 416 cfs used to drive the hydraulic pumps is returned to the Yakima River at river mile 35.8<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1694Lower Yakima River2025-09-10T18:21:51Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749 cfs. At Chandler Pump Station, the 416 cfs used to drive the hydraulic pumps is returned to the Yakima River at river mile 35.8<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1693Lower Yakima River2025-09-10T18:11:26Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749 cfs. At Chandler Pump Station, the 416 cfs used to drive the hydraulic pumps is returned to the Yakima River<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1692Lower Yakima River2025-09-10T18:10:57Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749cfs. At Chandler Pump Station, the 416cfs used to drive the hydraulic pumps is returned to the Yakima River<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1691Lower Yakima River2025-09-10T17:27:36Z<p>Jyeager: /* Citations */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749cfs. At Chandler Pump Station, the 416cfs used to drive the hydraulic pumps is returned to the Yakima River<ref>Senate Report 106-488 - Chandler Pumping Plant at Prosser Diversion Dam, Washington. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300cfs to 600cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1690Lower Yakima River2025-09-10T17:25:52Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749cfs. At Chandler Pump Station, the 416cfs used to drive the hydraulic pumps is returned to the Yakima River<ref>Senate Report 106-488 - CHANDLER PUMPING PLANT AT PROSSER DIVERSION DAM, WASHINGTON. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300cfs to 600cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1689Lower Yakima River2025-09-10T17:25:16Z<p>Jyeager: /* Facilities */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
<br />
'''Kennewick Irrigation District and pumping'''<br />
<br />
The Kennewick Irrigation District (KID) currently diverts water from the Yakima River at Prosser, Washington. The water flows down Chandler Canal to the Chandler Pump Station where it is pumped into the KID's Main Canal. Up to 333 cubic feet per second (cfs) of irrigation water is pumped into the Main Canal. The pumps in Chandler Pump Station are hydraulically driven turbine pumps which require approximately 1.25 gallons of water to lift (pump) one gallon of water into KID's Main Canal. Therefore, furnishing KID's irrigation and pumping water requires a peak diversion from the Yakima River of 749cfs. At Chandler Pump Station, the 416cfs used to drive the hydraulic pumps is returned to the Yakima River<ref>Senate Report 106-488 - CHANDLER PUMPING PLANT AT PROSSER DIVERSION DAM, WASHINGTON. (2025, September 10). <nowiki>https://www.congress.gov/committee-report/106th-congress/senate-report/488/1</nowiki></ref>.<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]: A diversion dam, on the Yakima River near Prosser, is a 9-foot-high concrete weir. The Prosser Diversion Dam feeds the Chandler Canal which serves Kennewick Division of the Bureau of Reclamation's Yakima Project.<br />
<br />
Chandler Canal:<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Yakima_Basin_Key_References&diff=1688Yakima Basin Key References2025-09-10T16:58:38Z<p>Jyeager: </p>
<hr />
<div>The Yakima Basin Fish and Wildlife Recovery Board hosts a [https://www.zotero.org/groups/1635495/yakima_basin_references/library reference library on Zotero]. The reference library is focused on the Yakima Basin and is a great resource for finding references or literature.<br />
<br />
We have put together a short list of key references for the Yakima River Basin.<br />
<br />
<br />
'''Historical and General References'''<br />
<br />
* Water Powers of the Cascade Range, Part III. Yakima River Basin Washington by Parker, G. and F. Storey in 1916<ref>Parker, G., and F. Storey. 1916. Water Powers of the Cascade Range, Part III. Yakima River Basin Washington. U.S. Geological Survey, Water Supply Paper 369.</ref>. This report assesses the potential for hydropower development in the Yakima Basin, information from stream flow records, river plans and profiles, reservoir surveys, and field reconnaissance. [https://pubs.usgs.gov/wsp/0369/report.pdf See PDF]<br/><br/><br />
* A 1950 report on stream surveys in the Columbia River and Yakima River Basin by Bryant and Parkhurst<ref>Bryant, F. G., and Z. E. Parkhurst. 1950. Survey of the Columbia River and its tributaries: 4. Area III - Washington stream from the Klickitat and Snake Rivers to Grand Coulee Dam, with notes on the Columbia and its tributaries above Grand Coulee Dam. Page 108. U.S. Fish and Wildlife Service, Special Scientific Report - Fisheries 57.</ref>. This report includes information from1930's and 1940's stream surveys of the Yakima Basin. Also has information on dams, irrigation canals, fish screens, stream flows, fish runs, and fish distribution. [https://ybfwrb.org/wp-content/uploads/2017/10/Bryant-and-Parkhurst-1950.pdf See PDF]<br/><br/><br />
* Yakima Basin River Mile Index 1964<ref>Columbia Basin Inter-Agency Committee. 1964. River Mile Index Yakima River.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/CBIAC_1964_Yakima_River_Mile_Index.pdf See PDF]<br/><br/><br />
* In 1990, Cuffney et al. with the USGS conducted an ecological survey of fish communities, water quality conditions, invertebrates, and algal communities at 25 sites in the Yakima River Basin<ref>Cuffney, T. F., M. R. Meador, S. D. Porter, and M. E. Gurtz. 1997. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River Basin, WA, 1990. Page 94. U.S. Geological Survey, Water-Resources Investigations Report 96–4280.</ref>. [https://pubs.usgs.gov/wri/1996/4280/report.pdf See PDF]<br/><br/><br />
* The impacts of irrigation development on anadromous fish in the Yakima Basin by Bob Tuck as his Master's Thesis in 1995<ref>Tuck, R. L. 1995. The impacts of irrigation development on anadromous fish in the Yakima Basin. Central Washington University, Ellensburg, WA.</ref>. This document provides a good background on irrigation development in the Yakima River Basin. [https://digitalcommons.cwu.edu/etd/1785/ See PDF]<br/><br/><br />
<br />
*The Bureau of Reclamation assessment of fish passage at all storage dams of the Yakima Project in 2003 and revised in 2005<ref>USBR. 2003. Phase 1 Assessment Report Storage Dam Fish Passage Study Yakima Project, Washington. U.S Department of the Interior, Bureau of Reclamation, Technical Series PN-YDFP-001.</ref>. This document provides detailed information on the storage dams, facilities, operations, and fish passage considerations. [https://ybfwrb.org/wp-content/uploads/2024/04/Phase1_Assessment_ReportStorage-Dam-Fish-Passage-Stufy.pdf See PDF]<br />
<br />
<br />
'''The Reaches Project'''<br />
<br />
* The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington by Stanford et al. 2002<ref>Stanford, J., E. Snyder, M. Lorang, D. Whited, P. Matson, and J. Chaffin. 2002. The reaches project: ecological and geomorphic studies supporting normative flows in the Yakima River Basin, Washington. Page 152. Bonneville Power Administration, DOE/BP-00005854-1, Portland, OR.</ref>. The purpose of this research was to determine the ecology of major floodplain reaches of the Yakima River: Cle Elum, Kittitas, Naches, Union Gap and Wapato. [https://www.osti.gov/servlets/purl/828280 See PDF]<br/><br/><br />
* Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions by Snyder and Stanford in 2001<ref>Snyder, E. B., and J. A. Stanford. 2001. Review and Synthesis of River Ecological Studies in the Yakima River, Washington, with Emphasis on Flow and Salmon Habitat Interactions. Flathead Lake Biological Station, University of Montana, Polson, MT.</ref>. This report provides a good summary of the scientific information about the ecology of the Yakima River ecosystem, particularly in the context of salmonid restoration. [https://ybfwrb.org/wp-content/uploads/2017/10/Snyder-and-Stanford-2001.pdf See PDF]<br />
<br />
<br />
'''Yakima River Adjudication'''<br />
<br />
* The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate by Sid Ottem in 2008<ref>Ottem, S. P. 2008. The General Adjudication of the Yakima River: Tributaries for the Twenty-First Century and a Changing Climate. Journal of Environmental Law & Litigation 23(2):275–256.<br />
</ref>. [https://hdl.handle.net/1794/9188 See PDF]<br />
<br />
<br />
'''The Yakima River Basin Water Enhancement Project'''<br />
* Report on Biologically Based Flows for the Yakima River Basin by the System Operations Advisory Committee in 1999<ref>Tuck, R., J. Thomas, J. Easterbrooks, and P. Monk. 1999. Report on biologically based flows for the Yakima River Basin. The System Operations Advisory Committee.</ref>. The purpose of this report is to provide Congress and the Secretary of the Interior with a review of factors affecting anadromous fish resources in the Yakima River and recommend processes and procedures required to determine biologically based flows for increasing the abundance of salmon and steelhead. [https://www.usbr.gov/pn/programs/yrbwep/reports/SOAC_BioBaseFlows.pdf See PDF]<br/><br/><br />
* The Bureau of Reclamation developed an Interim Comprehensive Basin Operating Plan for the Yakima Project in 2002<ref>Bureau of Reclamation. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project.</ref>. This document provides a framework within which the Bureau of Reclamation operates the Yakima Project. It presents a historical context of the project and its current operation, describes its legal and institutional aspects, articulates the impacts of project operations on the natural resources of the basin, analyzes various operational alternatives, and recommends strategies and operational changes that will address the goals of Title XII. [https://www.usbr.gov/pn/programs/yrbwep/reports/operatingplan/finaliop.pdf See PDF]<br/><br/><br />
* In 2011, HDR Engineering, Inc and Anchor QEA completed the Yakima River Basin study: modeling of reliability and flows technical memorandum<ref>HDR Engineering, Inc and Anchor QEA. 2011. Yakima River Basin study: modeling of reliability and flows technical memorandum. Page 48. U.S. Bureau of Reclamation, 08CA10677A ID/IQ, Task 6.</ref>. This technical memorandum describes the surface and groundwater resources of the Yakima River Basin, water development history for the U.S. Bureau of Reclamation’s Yakima Project, and Yakima Project facilities and operations, including effects on flows and fisheries. [https://www.usbr.gov/pn/programs/yrbwep/reports/tm/6modreliabtyflow.pdf See PDF]<br/><br/><br />
* The Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement by the U.S. Bureau of Reclamation and Washington State Department of Ecology in 2012<ref>Ecology, D. of. 2012. Yakima River Basin Integrated Water Resource Management Plan: Final Programmatic Environmental Impact Statement. U.S. Bureau of Reclamation and Washington State Department of Ecology, Yakima, WA.</ref>. The Integrated Plan identifies a comprehensive approach to water resources and ecosystem restoration improvements in the Yakima River basin. The Integrated Plan includes seven elements: reservoir fish passage, structural and operational changes to existing facilities, surface water storage, groundwater storage, habitat/watershed protection and enhancement, enhanced water conservation, and market reallocation. [https://ybfwrb.org/wp-content/uploads/2017/10/DOE-2012.pdf See PDF]<br/><br/><br />
* The Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033<ref>Yakima Basin Integrated Plan Habitat Subcommittee. 2022. Yakima Basin Integrated Plan: Habitat 10-year Plan for 2023-2033.</ref>. [https://ybfwrb.org/wp-content/uploads/2025/08/YBIP_Habitat_10-year_Mainstem_Habitat_Plan2022.pdf See PDF]<br />
<br />
<br />
'''Salmon, Steelhead, and Bull Trout'''<br />
* In 2001, The Washington State Conservation Commission produced the salmonid habitat limiting factors report for the Yakima River Watershed, Water Resource Inventory Areas 37-39<ref>Haring, D. 2001. Habitat limiting factors Yakima River Watershed, Water Resource Inventory Areas 37-39 : Final Report. Page 364. Washington State Conservation Commission.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Haring-2001.pdf See PDF]<br/><br/><br />
* The 2004 Yakima Subbasin Plan produced by the Yakima Subbasin Fish and Wildlife Planning Board<ref>Yakima Subbasin Fish and Wildlife Planning Board. 2004. Yakima Subbasin Plan.</ref>. The subbasin plan lays out objectives and strategies for restoration of fish and wildlife habitat and populations in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Planning_Board_2004.pdf See PDF]<br/><br/><br />
* The 2009 Yakima Steelhead Recovery Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2009. Yakima Steelhead Recovery Plan.</ref>. The Yakima Basin Fish & Wildlife Recovery Board developed this plan to guide steelhead recovery efforts in the Yakima Basin. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2009.pdf See PDF]<br/><br/><br />
* The 2011 Viable Salmonid Population Section for the Yakima Steelhead Research, Monitoring and Evaluation Plan<ref>Yakima Basin Fish and Wildlife Recovery Board. 2011, May. Final Draft: VSP Section Yakima Steelhead Research, Monitoring and Evaluation Plan.</ref>. This document is a supplement to the Yakima Steelhead Recovery Plan that identifies specific research, monitoring and evaluation (RM&E) actions that address the uncertainties identified in the recovery plan. [https://ybfwrb.org/wp-content/uploads/2017/10/Yakima_Basin_Fish_and_Wildlife_Recovery_Board_2011.pdf See PDF]<br/><br/><br />
* Yakima Basin Bull Trout Action Plan 2012<ref>Reiss, K. Y., J. Thomas, E. Anderson, and J. Cummins. 2012. Yakima Basin Bull Trout Action Plan. Yakima Basin Fish and Wildlife Recovery Board.</ref>.The Yakima Bull Trout Action Plan (YBTAP) is a locally developed summary of information on bull trout (''Salvelinus confluentus'') populations in the Yakima Basin. It includes information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2017/10/Reiss_et_al_2012.pdf See PDF]<br/><br/><br />
* The Yakima Bull Trout Action Plan 2017 Update<ref>Yakima Basin Fish and Wildlife Recovery Board. 2017. Yakima Bull Trout Action Plan 2017 Action Update.</ref>. An update to the 2012 Bull Trout Action Plan that incorporates new information on population status, trend and distribution, habitat, a detailed analysis of threats by life stage for each population, and specific monitoring and restoration actions that address those threats. [https://ybfwrb.org/wp-content/uploads/2020/12/2017_BTAP_Actions_Update.pdf See PDF]<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Main_Page&diff=1687Main Page2025-09-10T16:56:51Z<p>Jyeager: </p>
<hr />
<div><strong>Welcome to Yakipedia, the online knowledge base hosted by the Yakima Basin Fish and Wildlife Recovery Board.</strong><br />
<br />
Our goal is to create an informational resource for the Yakima Basin and its important tie to fisheries and wildlife resources. <br />
<br />
This online knowledge base will provide a place for folks to learn about the rich history of the Yakima Basin, learn about events and activities that have influenced where we are today, and provide a community resource for collaboration to move the Yakima Basin forward.<br />
<br />
<br />
<br />
A list of Yakima Basin organizations and web resources. [[Yakima Basin Organizations and Web Resources|See our Yakima Basin Organization and Web Resources Page.]]<br />
<br />
We have also compiled a list of key references for the Yakima Basin. [[Yakima Basin Key References|See our Key References Web Page.]]<br />
<br />
<br />
We are also developing an overview of [[historical references on fisheries in the Yakima Basin]]<br />
<br />
<br />
For a growing list of acronyms and vocabulary to help make sense of our work world, check out our [[Glossary]]!</div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1686Lower Yakima River2025-09-09T20:08:09Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
Lower Yakima River flow has a long history and is influenced by storage dams in the Yakima headwaters, irrigation dams, diversions, agriculture, streams, groundwater, return flows, power production, fish, recreation, and a number of other factors; making flow complicated.<br />
<br />
There are four large diversions in the Lower Yakima River including Kennewick Irrigation District (KID), Columbia Irrigation District (CID), Kiona Irrigation District, and Richland Irrigation District.<br />
<br />
Two diversion dams, Prosser Diversion Dam and Wanawish Dam.<br />
<br />
One power plant, Chandler Power Plant.<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]<br />
<br />
Chandler Canal<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500 cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1682Water stargrass2025-09-08T18:59:49Z<p>Jyeager: /* Digital Resources */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River storage reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for stargrass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticeable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operators to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* Pelly and others produced a [https://ybfwrb.org/wp-content/uploads/2025/09/WSG-Harvesting-Assessment_2024_rev-1.pdf 2024 report] on water stargrass removal on dissolved oxygen, temperature, and water velocity in the Lower Yakima River.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include:<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) and partners have researched and piloted several techniques to control water stargrass in the Lower Yakima River. Starting with the [https://ybfwrb.org/wp-content/uploads/2025/09/WSGRecommendations_BCD_Rev-3.pdf 2022 water stargrass recommendation report] and followed by the Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD and Mid-Columbia Fisheries completed an [https://ybfwrb.org/wp-content/uploads/2025/09/7_WSG-Emergency-Drought_Final.pdf emergency drought response plan] for control of water stargrass in low water years. <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf white paper] that provides a good overview of stargrass control strategies and efforts in the Lower Yakima River, the coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. The Benton Conservation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/FY24-Harvesting-Operations_Final_240222.pdf report] on water stargrass mechanical harvest operations from 2021-2023. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodging it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stargrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stargrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video]<br />
<br />
UW Burke Herbarium - [https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Heteranthera%20dubia Water Stargrass page]<br />
<br />
[https://drive.google.com/drive/folders/1OEBjOyEHErkdt1ead5XO2blkzYJb1DvR?usp=drive_link Water Stargrass Coalition Pictures] Includes an assortment of pictures ranging from hand-pulling efforts to conditions in the Lower Yakima River. <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1681Water stargrass2025-09-08T18:58:24Z<p>Jyeager: /* Digital Resources */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River storage reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for stargrass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticeable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operators to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* Pelly and others produced a [https://ybfwrb.org/wp-content/uploads/2025/09/WSG-Harvesting-Assessment_2024_rev-1.pdf 2024 report] on water stargrass removal on dissolved oxygen, temperature, and water velocity in the Lower Yakima River.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include:<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) and partners have researched and piloted several techniques to control water stargrass in the Lower Yakima River. Starting with the [https://ybfwrb.org/wp-content/uploads/2025/09/WSGRecommendations_BCD_Rev-3.pdf 2022 water stargrass recommendation report] and followed by the Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD and Mid-Columbia Fisheries completed an [https://ybfwrb.org/wp-content/uploads/2025/09/7_WSG-Emergency-Drought_Final.pdf emergency drought response plan] for control of water stargrass in low water years. <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf white paper] that provides a good overview of stargrass control strategies and efforts in the Lower Yakima River, the coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. The Benton Conservation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/FY24-Harvesting-Operations_Final_240222.pdf report] on water stargrass mechanical harvest operations from 2021-2023. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodging it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stargrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stargrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video]<br />
<br />
UW Burke Herbarium - [https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Heteranthera%20dubia Water Stargrass page]<br />
<br />
[https://drive.google.com/drive/folders/1OEBjOyEHErkdt1ead5XO2blkzYJb1DvR?usp=drive_link Water Stargrass Coalition Pictures] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1680Water stargrass2025-09-08T18:49:46Z<p>Jyeager: /* Stargrass Research and Monitoring */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River storage reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for stargrass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticeable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operators to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* Pelly and others produced a [https://ybfwrb.org/wp-content/uploads/2025/09/WSG-Harvesting-Assessment_2024_rev-1.pdf 2024 report] on water stargrass removal on dissolved oxygen, temperature, and water velocity in the Lower Yakima River.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include:<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) and partners have researched and piloted several techniques to control water stargrass in the Lower Yakima River. Starting with the [https://ybfwrb.org/wp-content/uploads/2025/09/WSGRecommendations_BCD_Rev-3.pdf water stargrass recommendation report in 2022] and followed by the Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD and Mid-Columbia Fisheries completed an [https://ybfwrb.org/wp-content/uploads/2025/09/7_WSG-Emergency-Drought_Final.pdf emergency drought response plan] for control of water stargrass in low water years. <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf white paper] that provides a good overview of stargrass control strategies and efforts in the Lower Yakima River, the coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. The Benton Conservation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/FY24-Harvesting-Operations_Final_240222.pdf report] on water stargrass mechanical harvest operations from 2021-2023. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodging it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stargrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stargrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video]<br />
<br />
UW Burke Herbarium - [https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Heteranthera%20dubia Water Stargrass page] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1679Water stargrass2025-09-08T18:46:47Z<p>Jyeager: /* Stargrass Control Efforts */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River storage reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for stargrass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticeable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operators to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* Pelly and others produced a [https://ybfwrb.org/wp-content/uploads/2025/09/WSG-Harvesting-Assessment_2024_rev-1.pdf 2024 report] on water stargrass removal on dissolved oxygen, temperature, and water velocity in the Lower Yakima River.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include: '''REVIEW TEAM- help us update!'''<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) and partners have researched and piloted several techniques to control water stargrass in the Lower Yakima River. Starting with the [https://ybfwrb.org/wp-content/uploads/2025/09/WSGRecommendations_BCD_Rev-3.pdf water stargrass recommendation report in 2022] and followed by the Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD and Mid-Columbia Fisheries completed an [https://ybfwrb.org/wp-content/uploads/2025/09/7_WSG-Emergency-Drought_Final.pdf emergency drought response plan] for control of water stargrass in low water years. <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf white paper] that provides a good overview of stargrass control strategies and efforts in the Lower Yakima River, the coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. The Benton Conservation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/FY24-Harvesting-Operations_Final_240222.pdf report] on water stargrass mechanical harvest operations from 2021-2023. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodging it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stargrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stargrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video]<br />
<br />
UW Burke Herbarium - [https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Heteranthera%20dubia Water Stargrass page] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1678Water stargrass2025-09-08T18:11:25Z<p>Jyeager: /* Overview and Concerns */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River storage reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for stargrass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticeable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operators to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include: '''REVIEW TEAM- help us update!'''<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) has researched and piloted several techniques to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD and Mid-Columbia Fisheries completed an emergency drought response plan for control of water stargrass in low water years. '''POST AND LINK COPY''' <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf white paper] that gives a good overview of stargrass control strategies and efforts in the Lower Yakima River, the coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodging it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stargrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stargrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video]<br />
<br />
UW Burke Herbarium - [https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Heteranthera%20dubia Water Stargrass page] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1677Water stargrass2025-09-08T18:08:03Z<p>Jyeager: /* Digital Resources */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River irrigation reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for star grass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operaters to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include: '''REVIEW TEAM- help us update!'''<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) has researched and piloted several techniques to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD and Mid-Columbia Fisheries completed an emergency drought response plan for control of water stargrass in low water years. '''POST AND LINK COPY''' <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf white paper] that gives a good overview of stargrass control strategies and efforts in the Lower Yakima River, the coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodign it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stragrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stagrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video]<br />
<br />
UW Burke Herbarium - [https://burkeherbarium.org/imagecollection/taxon.php?Taxon=Heteranthera%20dubia Water Stargrass page] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1676Water stargrass2025-09-08T17:58:43Z<p>Jyeager: /* Stargrass Control Efforts */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River irrigation reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for star grass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operaters to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include: '''REVIEW TEAM- help us update!'''<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) has researched and piloted several techniques to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD and Mid-Columbia Fisheries completed an emergency drought response plan for control of water stargrass in low water years. '''POST AND LINK COPY''' <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf white paper] that gives a good overview of stargrass control strategies and efforts in the Lower Yakima River, the coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodign it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stragrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stagrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1675Water stargrass2025-09-08T17:54:18Z<p>Jyeager: /* Stargrass Research and Monitoring */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River irrigation reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for star grass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operaters to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include: '''REVIEW TEAM- help us update!'''<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton Conservation District installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and Benton Conservation District have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) has researched and piloted several techniques to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD an Mid-Columbia Fisheries completed an emergency drought response plan for control of water stargrass in low water years. '''POST AND LINK COPY''' <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a white paper that gives a good overview of stargrass control strategies and efforts in the Lower Yakima River, [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf see PDF]. The coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodign it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stragrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stagrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1674Water stargrass2025-09-08T17:53:07Z<p>Jyeager: /* Stargrass Research and Monitoring */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River irrigation reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for star grass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operaters to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf 2009 report]<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River.<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>.<br />
* Aaron Pelly's [https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900890782401842 2020 Master's Thesis] focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>.<br />
* The USGS released a [https://doi.org/10.31223/X5JT8P 2024 draft report]<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include: '''REVIEW TEAM- help us update!'''<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton CD installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and BCD have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) has researched and piloted several techniques to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD an Mid-Columbia Fisheries completed an emergency drought response plan for control of water stargrass in low water years. '''POST AND LINK COPY''' <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a white paper that gives a good overview of stargrass control strategies and efforts in the Lower Yakima River, [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf see PDF]. The coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodign it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stragrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stagrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1673Water stargrass2025-09-08T17:48:06Z<p>Jyeager: /* Stargrass Research and Monitoring */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River irrigation reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for star grass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operaters to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A 2009 report<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River. [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf See PDF]<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf See PDF]<br />
* Aaron Pelly's 2020 Master's Thesis focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>. [https://doi.org/10.7273/000004124 See PDF]<br />
* The USGS released a 2024 draft report<ref>Sheibley, R.W., and Foreman, J.R., 2024, Water stargrass biomass, stream metabolism estimates, and nutrient data quality control data for the lower Yakima River: June 2018 through September 2020 (ver. 2.0, August 2025): U.S. Geological Survey data release, <nowiki>https://doi.org/10.5066/P95978KZ</nowiki>.</ref> on stargrass and water quality in the Lower Yakima River from 2018-2020 [https://doi.org/10.31223/X5JT8P See PDF]. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include: '''REVIEW TEAM- help us update!'''<br />
<br />
'''Monitoring Gages'''<br />
<br />
USGS and Benton CD installed monitoring gages as part of the water stargrass research efforts. The gages were installed in the lower Yakima River at Prosser (2018 - 2024), Benton City (Kiona; 2018 - 2025) and West Richland (Van Giesen; 2018 - 2025). The gage at Prosser was operated under funding from PNNL research from 2021 - 2024. Benton City and Van Giesen have operated through Department of Ecology and USGS funding from 2018 - 2025. The archived data for these sites can be retrieved from the USGS database:<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12509489/#dataTypeId=continuous-00010-0&period=P7D&showMedian=true Prosser Gage]<br />
<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D Kiona Gage]<br />
* [https://waterdata.usgs.gov/monitoring-location/USGS-12511800/#dataTypeId=continuous-00010-0&period=P7D Van Giesen Bridge Gage]<br />
<br />
<br />
'''Biomass Surveys'''<br />
* USGS and BCD have collected biomass samples at Prosser (2018 - 2020) and Kiona and Van Giesen (2018 - present). Funding for these efforts has been through Department of Ecology Centennial funding and YBFWRB funding (2022). Samples are collected between June - September to document the rate growth and estimate the total annual biomass during the growing season. Data through 2020 are available in USGS 2024 report. Data 2021 - 2025 are in review and will be published by USGS in 2027.<br />
<br />
<br />
'''Drone Surveys'''<br />
<br />
* Benton Conservation District and Benton County Mosquito Control Board (BCMCB) are documenting the seasonal biomass using drone imagery at key locations on the lower river as part of the efforts to evaluate mechanical harvesting effectiveness as well as seasonal growth. Drone images are available upon request submissions to BCD. <br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) has researched and piloted several techniques to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD an Mid-Columbia Fisheries completed an emergency drought response plan for control of water stargrass in low water years. '''POST AND LINK COPY''' <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a white paper that gives a good overview of stargrass control strategies and efforts in the Lower Yakima River, [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf see PDF]. The coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodign it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stragrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stagrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1672Water stargrass2025-09-08T17:38:08Z<p>Jyeager: /* Stargrass Research and Monitoring */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. It is a native species in the Yakima Basin, but its growth has exploded in recent decades. Historically, large floods and higher spring flows likely kept stargrass isolated to lower velocity parts of the river, but since the development of the Yakima River irrigation reservoirs, flood flows and the spring freshet have been significantly reduced (in order to store water in reservoirs for summer use). Prior to the 1990s, high fine sediment levels from irrigation runoff likely suppressed stargrass growth by blocking sunlight. Major efforts were made by irrigation districts and state and federal partners to reduce the erosion that caused high fine sediment levels in the summer, significantly cleaning up the river and reducing the associated levels of DDT and other toxins in the Lower Yakima- but also improving growth conditions for star grass. <br />
<br />
Today, water stargrass is prolific in most stretches of the lower 47 miles of the Yakima River, below Prosser Diversion Dam, and is becoming more noticable upstream of there too. Water stargrass can form a bank to bank monoculture and grows from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. Water stargrass has many major negative impacts on the river: <br />
<br />
* Stargrass degrades migration conditions for salmon, steelhead and lamprey by:<br />
** Blocking fish movement through fish ladders and at its worst, entire river channels,<br />
** Causing major daily fluctuations in dissolved oxygen and pH levels due to stargrass respiration and photosynthesis,<br />
** Improving habitat for warmwater predatory fish like smallmouth bass, increasing predation rates on salmon smolts (young fish travelling to the ocean), and<br />
** Changing local habitat conditions including temperature, sediment and insect populations in ways that reduce their value for juvenile anadromous fish.<br />
* Stargrass has essentially eliminated fall chinook spawning in the lower river by growing over previously productive spawning areas and locking in spawning gravels and causing fine sediment deposition on top of them.<br />
* Stargrass often creates stagnant water areas that support mosquito breeding, increasing human health risk from mosquito-borne illnesses and increasing the costs of mosquito control efforts.<br />
* Drifting water stargrass often plugs or block irrigation intakes, making them hard to operate and requiring operators to do almost continual maintenance to keep diversions functional.<br />
* Dense growth of water stargrass interferes with recreational activities such as swimming, boating and fishing and leads to the broad public perception that the river is 'gross'.<br />
* Stargrass can make it harder to measure river flows (essential for river management) when it fills so much of the river that the surface level rises, requiring river gage operaters to have to frequently visit and re-calibrate gages to ensure accurate flow measurement.<br />
<br />
== Stargrass Research and Monitoring ==<br />
Multiple studies focused on water stargrass and its impacts on the Yakima River have been completed or are on-going, and new monitoring and research work is being developed to ensure that expanding treatment efforts are effective. Completed studies include: <br />
<br />
* A 2009 report<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and the South Yakima Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River. [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf See PDF]<br />
* The [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf 2011 Lower Yakima River Assessment] completed by the Benton Conservation District includes a chapter on water stargrass and the issues it causes<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf See PDF]<br />
* Aaron Pelly's 2020 Master's Thesis focuses on water stargrass and its impacts on water quality in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>. [https://doi.org/10.7273/000004124 See PDF]<br />
* The USGS and Benton Conservation District released a 2025 draft report on stargrass and water quality in the Lower Yakima River from 2018-2020 [https://doi.org/10.31223/X5JT8P See PDF]. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
Ongoing monitoring efforts include: '''REVIEW TEAM- help us update!'''<br />
<br />
* establishment of USGS WAter quality gages<br />
* BIOMASS SURVEYS<br />
* DRONE SURVEYS<br />
<br />
== Stargrass Control Efforts ==<br />
<br />
Over the last decade, the Benton County Conservation District (BCD) has researched and piloted several techniques to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in detail in [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf this BCD report] <ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> <br />
<br />
In 2024, BCD an Mid-Columbia Fisheries completed an emergency drought response plan for control of water stargrass in low water years. '''POST AND LINK COPY''' <br />
<br />
Starting in 2024, key partners came together to formalize the Water Stargrass Coalition and develop a shared strategy for addressing the negative impacts of water stargrass on the Lower Yakima. In the spring of 2025, the leadership group of the Yakima Basin Integrated Plan focused on highlighting the importance of reducing stargrass impacts and securing significant financial investments to accelerate work on the ground. As part of this effort, the Roza Irrigation District produced a white paper that gives a good overview of stargrass control strategies and efforts in the Lower Yakima River, [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf see PDF]. The coalition is implementing several pilot projects in the summer/fall of 2025 and is working on developing a longer-term work plan to coordinate activities and secure support and funding for expanding control work and associated monitoring and research in the future. <br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. Several hand-pulling projects have been completed over the last decade, and have shown that treatments can improve water quality, reduce future stargrass growth, and restore conditions that support fall chinook spawning. Hand-pulling is relatively slow and works best in shallower areas and lower flow velocities, limiting its broad application throughout the river; it can be effective in clearing smaller priority areas. <br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesting typically uses a floating barge/boat equipped with either a cutter head (which typically mow the plan above the roots) or a roller (which can pull the plants, including roots, up, resulting in longer term control). Harvested plants may be removed from the water for onshore disposal or left in river to be washed downstream (allowing much more rapid operations). Mechanical harvesting began in 2021, when BCD acquired an [https://lakeweedharvester.com/eco-harvester/ Ecoharvester]. ,. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, the Benton City area and Prosser Dam pool. Pilot work has help determine where the harvester can and cannot operate well, and has confirmed that when using the roller head, it can significantly reduce plant densities in a way that persists in subsequent years. Approximately 16 acres were harvested in 2024. Several additional harvesters of varying sizes have been ordered in 2025 and should be fully operational in 2026. Partners are also exploring the use of land-based and amphibious harvesting equipment, including a summer of 2025 pilot of a spyder excavator led by WDFW. Pilots are also underway to test the use of hydraulic jets and suction dredging to control stargrass by dislodign it from the stream bed,. <br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed; herbicides being considered include endothall, imazamox, carfentrazone-ethyl, and fluridone. Local partners are working closely with US Army Corps of Engineers and Bureau of Reclamation aquatic plant management specialists who have experience with similar work in other area to evaluate whether and how herbicide treatments could be piloted in the Yakima River. <br />
<br />
'''Flow Management'''<br />
<br />
Flow conditions have a major impact on stargrass growth. In years where high, cool and turbid flows last through late spring, stargrass growth is significantly reduced; in low flow years it starts much earlier and grows much faster. This is due to a combination of reduced light availability for growing plants and cooler temperatures slowing growth. Higher flows- typical of winter and spring floods, break off stargrass and may even remove entire plants, including the roots when velocities are high enough to scour the bed, reducing the extent of stargrass in the next growing season. There is also anecdotal evidence that late spring/summer pulse flows released by the Bureau of Reclamation to encourage sockeye and summer chinook migration dislodge and move significant amounts of stargrass downstream; while this can create short-term problems at fish ladders and irrigation diversions, it has also been reported to have reduced stargrass issues at these sites for weeks after. The Water Stargrass Coalition is working to identify flow and turbidity management strategies that can help reduce the impacts of stragrass on the river while also meeting other fish and water supply objectives. <br />
<br />
== Digital Resources ==<br />
Benton Conservation District - [https://www.bentoncd.org/water-stargrass-removal Water Stargrass Management Page]. [https://www.bentoncd.org/saving-our-river BCD Water Stagrass Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Water Stargrass Page]<br />
<br />
State of Washington Water Research Center [https://www.youtube.com/watch?v=rEiqE0_KHkI Spring 2025 Seminar Series- Water Stargrass Video] <br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|TV <br />
|NBC<br />
|[https://www.nbcrightnow.com/news/crews-remove-water-stargrass-from-the-yakima-river-to-save-salmon-and-bring-balance-to/article_32aa5088-107a-439c-b69f-5c15e4d165e0.html Crews Remove Water Stargrass from the Yakima River to Save Salmon]<br />
|9/7/2025<br />
|<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|9/4/2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|8/28/2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1667Lower Yakima River2025-09-05T16:56:44Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
'''Power Subordination'''<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]<br />
<br />
Chandler Canal<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500 cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1666Water stargrass2025-09-05T16:55:13Z<p>Jyeager: /* Media Coverage */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. In the Lower Yakima River, water stargrass is prolific in many stretches of the lower 47 miles, below Prosser Diversion Dam. Water stargrass forms a bank to bank monoculture and can grow from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. <br />
<br />
Water stargrass causes a suite of issues including:<br />
<br />
* River displacement from total volume of water stargrass<br />
* Increased sedimentation from reduced streamflow<br />
* Changes to bottom substrates and gravel quality that reduce salmonid spawning habitat <br />
* Changes to fish migration<br />
* Changes in water quality including fluctuations in dissolved oxygen levels and pH from stargrass respiration and photosynthesis<br />
* Plugged or or block irrigation screens and fish ladders<br />
* Reduced recreation opportunities and challenges to boating and fishing<br />
<br />
== Studies ==<br />
Multiple studies have been completed or are on-going on stargrass and the Lower Yakima River. <br />
<br />
A 2009 report<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and Benton Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River. [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf See PDF]<br />
<br />
A 2011 assessment of the Lower Yakima River includes a chapter on water stargrass<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf See PDF]<br />
<br />
A 2020 Master's Thesis on water stargrass in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>. [https://doi.org/10.7273/000004124 See PDF]<br />
<br />
The USGS and Benton Conservation District released a 2025 draft report on stargrass and water quality in the Lower Yakima River from 2018-2020 [https://doi.org/10.31223/X5JT8P See PDF]. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
== Stargrass Control Efforts ==<br />
<br />
In the last few years Benton County Conservation District has ramped up efforts to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in this report by the Benton Conservation District<ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf Link]<br />
<br />
The Roza Irrigation District produced a good overview of stargrass control strategies and efforts in the Lower Yakima River, [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf see PDF]<br />
<br />
<br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. A small hand pulling effort has been tried over the last decade, but the effort would needed to be ramped up considerably to make an improvement. <br />
<br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesters cut the plant above the sediment and remove the cut plant material from the water. <br />
<br />
Mechanical harvesting began in 2021. With approximately 16 acres harvested in 2024. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, and Prosser Dam pool. A mechanical harvester reaches to a depth of about 3 feet and harvest would need to occur multiple times during the summer. <br />
<br />
<br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed. Potential herbicides being considered are only endothall, imazamox, carfentrazone-ethyl, and fluridone. <br />
<br />
<br />
<br />
'''Flows Management'''<br />
<br />
There is the potential that flow management strategies could help manage water stargrass. High flow events or managed pulse flows in the spring and early summer could reduce early water stargrass biomass growth. The mechanism is likely through bed scouring and erosion that help uproot the plant and reduce establishment and also reduces early plant growth. Although flow management has potential, a pilot study and monitoring would be an important step to better understand this control method.<br />
<br />
== Websites ==<br />
Benton Conservation District - Water Stargrass Management. [https://www.bentoncd.org/water-stargrass-removal Link] [https://www.bentoncd.org/saving-our-river Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - Water Stargrass. [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Link]<br />
<br />
State of Washington Water Research Center Spring 2025 Seminar Series- Water Stargrass Video [https://www.youtube.com/watch?v=rEiqE0_KHkI YouTube Link]<br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|September 4, 2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|August 28, 2025<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1665Water stargrass2025-09-05T16:51:18Z<p>Jyeager: /* Overview and Concerns */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. In the Lower Yakima River, water stargrass is prolific in many stretches of the lower 47 miles, below Prosser Diversion Dam. Water stargrass forms a bank to bank monoculture and can grow from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. <br />
<br />
Water stargrass causes a suite of issues including:<br />
<br />
* River displacement from total volume of water stargrass<br />
* Increased sedimentation from reduced streamflow<br />
* Changes to bottom substrates and gravel quality that reduce salmonid spawning habitat <br />
* Changes to fish migration<br />
* Changes in water quality including fluctuations in dissolved oxygen levels and pH from stargrass respiration and photosynthesis<br />
* Plugged or or block irrigation screens and fish ladders<br />
* Reduced recreation opportunities and challenges to boating and fishing<br />
<br />
== Studies ==<br />
Multiple studies have been completed or are on-going on stargrass and the Lower Yakima River. <br />
<br />
A 2009 report<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and Benton Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River. [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf See PDF]<br />
<br />
A 2011 assessment of the Lower Yakima River includes a chapter on water stargrass<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf See PDF]<br />
<br />
A 2020 Master's Thesis on water stargrass in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>. [https://doi.org/10.7273/000004124 See PDF]<br />
<br />
The USGS and Benton Conservation District released a 2025 draft report on stargrass and water quality in the Lower Yakima River from 2018-2020 [https://doi.org/10.31223/X5JT8P See PDF]. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
== Stargrass Control Efforts ==<br />
<br />
In the last few years Benton County Conservation District has ramped up efforts to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in this report by the Benton Conservation District<ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf Link]<br />
<br />
The Roza Irrigation District produced a good overview of stargrass control strategies and efforts in the Lower Yakima River, [https://ybfwrb.org/wp-content/uploads/2025/09/Revell_2025_WaterStargrassOverview.pdf see PDF]<br />
<br />
<br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. A small hand pulling effort has been tried over the last decade, but the effort would needed to be ramped up considerably to make an improvement. <br />
<br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesters cut the plant above the sediment and remove the cut plant material from the water. <br />
<br />
Mechanical harvesting began in 2021. With approximately 16 acres harvested in 2024. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, and Prosser Dam pool. A mechanical harvester reaches to a depth of about 3 feet and harvest would need to occur multiple times during the summer. <br />
<br />
<br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed. Potential herbicides being considered are only endothall, imazamox, carfentrazone-ethyl, and fluridone. <br />
<br />
<br />
<br />
'''Flows Management'''<br />
<br />
There is the potential that flow management strategies could help manage water stargrass. High flow events or managed pulse flows in the spring and early summer could reduce early water stargrass biomass growth. The mechanism is likely through bed scouring and erosion that help uproot the plant and reduce establishment and also reduces early plant growth. Although flow management has potential, a pilot study and monitoring would be an important step to better understand this control method.<br />
<br />
== Websites ==<br />
Benton Conservation District - Water Stargrass Management. [https://www.bentoncd.org/water-stargrass-removal Link] [https://www.bentoncd.org/saving-our-river Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - Water Stargrass. [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Link]<br />
<br />
State of Washington Water Research Center Spring 2025 Seminar Series- Water Stargrass Video [https://www.youtube.com/watch?v=rEiqE0_KHkI YouTube Link]<br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|September 4, 2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|August 28, 2025<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1664Water stargrass2025-09-05T16:47:41Z<p>Jyeager: /* Media Coverage */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. In the Lower Yakima River, water stargrass is prolific in many stretches of the lower 47 miles, below Prosser Diversion Dam. Water stargrass forms a bank to bank monoculture and can grow from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. <br />
<br />
Water stargrass causes a suite of issues including:<br />
<br />
* River displacement from total volume of water stargrass<br />
* Increased sedimentation from reduced streamflow<br />
* Changes to bottom substrates and gravel quality that reduce salmonid spawning habitat <br />
* Changes to fish migration<br />
* Changes in water quality including fluctuations in dissolved oxygen levels and pH from stargrass respiration and photosynthesis<br />
* Plugged or or block irrigation screens and fish ladders<br />
* Reduced recreation opportunities and challenges to boating and fishing<br />
<br />
== Studies ==<br />
Multiple studies have been completed or are on-going on stargrass and the Lower Yakima River. <br />
<br />
A 2009 report<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and Benton Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River. [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf See PDF]<br />
<br />
A 2011 assessment of the Lower Yakima River includes a chapter on water stargrass<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf See PDF]<br />
<br />
A 2020 Master's Thesis on water stargrass in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>. [https://doi.org/10.7273/000004124 See PDF]<br />
<br />
The USGS and Benton Conservation District released a 2025 draft report on stargrass and water quality in the Lower Yakima River from 2018-2020 [https://doi.org/10.31223/X5JT8P See PDF]. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
== Stargrass Control Efforts ==<br />
<br />
In the last few years Benton County Conservation District has ramped up efforts to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in this report by the Benton Conservation District<ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf Link] <br />
<br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. A small hand pulling effort has been tried over the last decade, but the effort would needed to be ramped up considerably to make an improvement. <br />
<br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesters cut the plant above the sediment and remove the cut plant material from the water. <br />
<br />
Mechanical harvesting began in 2021. With approximately 16 acres harvested in 2024. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, and Prosser Dam pool. A mechanical harvester reaches to a depth of about 3 feet and harvest would need to occur multiple times during the summer. <br />
<br />
<br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed. Potential herbicides being considered are only endothall, imazamox, carfentrazone-ethyl, and fluridone. <br />
<br />
<br />
<br />
'''Flows Management'''<br />
<br />
There is the potential that flow management strategies could help manage water stargrass. High flow events or managed pulse flows in the spring and early summer could reduce early water stargrass biomass growth. The mechanism is likely through bed scouring and erosion that help uproot the plant and reduce establishment and also reduces early plant growth. Although flow management has potential, a pilot study and monitoring would be an important step to better understand this control method.<br />
<br />
== Websites ==<br />
Benton Conservation District - Water Stargrass Management. [https://www.bentoncd.org/water-stargrass-removal Link] [https://www.bentoncd.org/saving-our-river Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - Water Stargrass. [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Link]<br />
<br />
State of Washington Water Research Center Spring 2025 Seminar Series- Water Stargrass Video [https://www.youtube.com/watch?v=rEiqE0_KHkI YouTube Link]<br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|September 4, 2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|August 28, 2025<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1663Water stargrass2025-09-05T16:47:21Z<p>Jyeager: /* Media Coverage */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. In the Lower Yakima River, water stargrass is prolific in many stretches of the lower 47 miles, below Prosser Diversion Dam. Water stargrass forms a bank to bank monoculture and can grow from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. <br />
<br />
Water stargrass causes a suite of issues including:<br />
<br />
* River displacement from total volume of water stargrass<br />
* Increased sedimentation from reduced streamflow<br />
* Changes to bottom substrates and gravel quality that reduce salmonid spawning habitat <br />
* Changes to fish migration<br />
* Changes in water quality including fluctuations in dissolved oxygen levels and pH from stargrass respiration and photosynthesis<br />
* Plugged or or block irrigation screens and fish ladders<br />
* Reduced recreation opportunities and challenges to boating and fishing<br />
<br />
== Studies ==<br />
Multiple studies have been completed or are on-going on stargrass and the Lower Yakima River. <br />
<br />
A 2009 report<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and Benton Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River. [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf See PDF]<br />
<br />
A 2011 assessment of the Lower Yakima River includes a chapter on water stargrass<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf See PDF]<br />
<br />
A 2020 Master's Thesis on water stargrass in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>. [https://doi.org/10.7273/000004124 See PDF]<br />
<br />
The USGS and Benton Conservation District released a 2025 draft report on stargrass and water quality in the Lower Yakima River from 2018-2020 [https://doi.org/10.31223/X5JT8P See PDF]. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
== Stargrass Control Efforts ==<br />
<br />
In the last few years Benton County Conservation District has ramped up efforts to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in this report by the Benton Conservation District<ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf Link] <br />
<br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. A small hand pulling effort has been tried over the last decade, but the effort would needed to be ramped up considerably to make an improvement. <br />
<br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesters cut the plant above the sediment and remove the cut plant material from the water. <br />
<br />
Mechanical harvesting began in 2021. With approximately 16 acres harvested in 2024. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, and Prosser Dam pool. A mechanical harvester reaches to a depth of about 3 feet and harvest would need to occur multiple times during the summer. <br />
<br />
<br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed. Potential herbicides being considered are only endothall, imazamox, carfentrazone-ethyl, and fluridone. <br />
<br />
<br />
<br />
'''Flows Management'''<br />
<br />
There is the potential that flow management strategies could help manage water stargrass. High flow events or managed pulse flows in the spring and early summer could reduce early water stargrass biomass growth. The mechanism is likely through bed scouring and erosion that help uproot the plant and reduce establishment and also reduces early plant growth. Although flow management has potential, a pilot study and monitoring would be an important step to better understand this control method.<br />
<br />
== Websites ==<br />
Benton Conservation District - Water Stargrass Management. [https://www.bentoncd.org/water-stargrass-removal Link] [https://www.bentoncd.org/saving-our-river Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - Water Stargrass. [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Link]<br />
<br />
State of Washington Water Research Center Spring 2025 Seminar Series- Water Stargrass Video [https://www.youtube.com/watch?v=rEiqE0_KHkI YouTube Link]<br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|September 4, 2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|August 28, 2025<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1662Water stargrass2025-09-05T16:46:40Z<p>Jyeager: /* Media Coverage */</p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. In the Lower Yakima River, water stargrass is prolific in many stretches of the lower 47 miles, below Prosser Diversion Dam. Water stargrass forms a bank to bank monoculture and can grow from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. <br />
<br />
Water stargrass causes a suite of issues including:<br />
<br />
* River displacement from total volume of water stargrass<br />
* Increased sedimentation from reduced streamflow<br />
* Changes to bottom substrates and gravel quality that reduce salmonid spawning habitat <br />
* Changes to fish migration<br />
* Changes in water quality including fluctuations in dissolved oxygen levels and pH from stargrass respiration and photosynthesis<br />
* Plugged or or block irrigation screens and fish ladders<br />
* Reduced recreation opportunities and challenges to boating and fishing<br />
<br />
== Studies ==<br />
Multiple studies have been completed or are on-going on stargrass and the Lower Yakima River. <br />
<br />
A 2009 report<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and Benton Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River. [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf See PDF]<br />
<br />
A 2011 assessment of the Lower Yakima River includes a chapter on water stargrass<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf See PDF]<br />
<br />
A 2020 Master's Thesis on water stargrass in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>. [https://doi.org/10.7273/000004124 See PDF]<br />
<br />
The USGS and Benton Conservation District released a 2025 draft report on stargrass and water quality in the Lower Yakima River from 2018-2020 [https://doi.org/10.31223/X5JT8P See PDF]. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
== Stargrass Control Efforts ==<br />
<br />
In the last few years Benton County Conservation District has ramped up efforts to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in this report by the Benton Conservation District<ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf Link] <br />
<br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. A small hand pulling effort has been tried over the last decade, but the effort would needed to be ramped up considerably to make an improvement. <br />
<br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesters cut the plant above the sediment and remove the cut plant material from the water. <br />
<br />
Mechanical harvesting began in 2021. With approximately 16 acres harvested in 2024. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, and Prosser Dam pool. A mechanical harvester reaches to a depth of about 3 feet and harvest would need to occur multiple times during the summer. <br />
<br />
<br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed. Potential herbicides being considered are only endothall, imazamox, carfentrazone-ethyl, and fluridone. <br />
<br />
<br />
<br />
'''Flows Management'''<br />
<br />
There is the potential that flow management strategies could help manage water stargrass. High flow events or managed pulse flows in the spring and early summer could reduce early water stargrass biomass growth. The mechanism is likely through bed scouring and erosion that help uproot the plant and reduce establishment and also reduces early plant growth. Although flow management has potential, a pilot study and monitoring would be an important step to better understand this control method.<br />
<br />
== Websites ==<br />
Benton Conservation District - Water Stargrass Management. [https://www.bentoncd.org/water-stargrass-removal Link] [https://www.bentoncd.org/saving-our-river Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - Water Stargrass. [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Link]<br />
<br />
State of Washington Water Research Center Spring 2025 Seminar Series- Water Stargrass Video [https://www.youtube.com/watch?v=rEiqE0_KHkI YouTube Link]<br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|September 4, 2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://kimatv.com/news/local/wdfw-project-targets-invasive-aquatic-plant-to-improve-habitat-in-yakima-river Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|August 28, 2025<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Water_stargrass&diff=1661Water stargrass2025-09-05T16:45:13Z<p>Jyeager: </p>
<hr />
<div>== Overview and Concerns ==<br />
<br />
Water stargrass (''Heteranthera dubia'') is a species of perennial aquatic plant in the ''Pontederiaceae'' family. It lives in freshwater such as lakes, rivers, and irrigation canals; preferring calmer waters. In the Lower Yakima River, water stargrass is prolific in many stretches of the lower 47 miles, below Prosser Diversion Dam. Water stargrass forms a bank to bank monoculture and can grow from stream bottom to the water surface and then continue growing horizontally forming a canopy at the water surface. It also forms dense vegetative mats over stream substrates covering gravels cobbles. <br />
<br />
Water stargrass causes a suite of issues including:<br />
<br />
* River displacement from total volume of water stargrass<br />
* Increased sedimentation from reduced streamflow<br />
* Changes to bottom substrates and gravel quality that reduce salmonid spawning habitat <br />
* Changes to fish migration<br />
* Changes in water quality including fluctuations in dissolved oxygen levels and pH from stargrass respiration and photosynthesis<br />
* Plugged or or block irrigation screens and fish ladders<br />
* Reduced recreation opportunities and challenges to boating and fishing<br />
<br />
== Studies ==<br />
Multiple studies have been completed or are on-going on stargrass and the Lower Yakima River. <br />
<br />
A 2009 report<ref>Wise, D. R., M. Zuroske, K. D. Carpenter, and R. L. Kiesling. 2009. Assessment of Eutrophication in the Lower Yakima River Basin, Washington 2004-07. Page 108. U.S. Geological Survey, Investigations Report 2009–5078.</ref> by the USGS and Benton Conservation District detailed a 2004-2007 assessment of eutrophication in the lower 116 miles of the Yakima River. This was one of the first studies that characterized the proliferation of water stargrass in the Lower Yakima River. [https://pubs.usgs.gov/sir/2009/5078/pdf/sir20095078.pdf See PDF]<br />
<br />
A 2011 assessment of the Lower Yakima River includes a chapter on water stargrass<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. 2011. Assessment of the Lower Yakima River in Benton County, Washington. Page 182. Benton Conservation District.</ref>. [https://ybfwrb.org/wp-content/uploads/2017/10/Lower_Yakima_Assessment.pdf See PDF]<br />
<br />
A 2020 Master's Thesis on water stargrass in the Lower Yakima River<ref>Pelly, A. C. 2020. Overabundant macrophyte growth alters ecosystem function in a lowland river. Washington State University.</ref>. [https://doi.org/10.7273/000004124 See PDF]<br />
<br />
The USGS and Benton Conservation District released a 2025 draft report on stargrass and water quality in the Lower Yakima River from 2018-2020 [https://doi.org/10.31223/X5JT8P See PDF]. The data is available on the USGS website, [https://data.usgs.gov/datacatalog/data/USGS:62d987d3d34e2842e1edcfcd link].<br />
<br />
== Stargrass Control Efforts ==<br />
<br />
In the last few years Benton County Conservation District has ramped up efforts to control water stargrass in the Lower Yakima River. Management and Control Techniques for Water Stargrass are discussed in this report by the Benton Conservation District<ref>Pelly, A., M. Appel, and R. Little. 2021. Management and Control Techniques for Water Stargrass in the Lower Yakima River. Benton Conservation District.</ref> [https://ybfwrb.org/wp-content/uploads/2021/10/Water-Stargrass-Management-Techniques_2021-09-17.pdf Link] <br />
<br />
<br />
'''Hand''' <br />
<br />
The most effective approach to manage stargrass is to remove the plant material at the roots. The simplest and most straight forward method is hand pulling with or without tools. A small hand pulling effort has been tried over the last decade, but the effort would needed to be ramped up considerably to make an improvement. <br />
<br />
<br />
'''Mechanical''' <br />
<br />
Mechanical harvesters cut the plant above the sediment and remove the cut plant material from the water. <br />
<br />
Mechanical harvesting began in 2021. With approximately 16 acres harvested in 2024. The focus of removal locations has been in the Yakima Delta area, the Wanawish Dam pool, and Prosser Dam pool. A mechanical harvester reaches to a depth of about 3 feet and harvest would need to occur multiple times during the summer. <br />
<br />
<br />
<br />
'''Herbicides''' <br />
<br />
Potential aquatic herbicide treatments are being assessed. Potential herbicides being considered are only endothall, imazamox, carfentrazone-ethyl, and fluridone. <br />
<br />
<br />
<br />
'''Flows Management'''<br />
<br />
There is the potential that flow management strategies could help manage water stargrass. High flow events or managed pulse flows in the spring and early summer could reduce early water stargrass biomass growth. The mechanism is likely through bed scouring and erosion that help uproot the plant and reduce establishment and also reduces early plant growth. Although flow management has potential, a pilot study and monitoring would be an important step to better understand this control method.<br />
<br />
== Websites ==<br />
Benton Conservation District - Water Stargrass Management. [https://www.bentoncd.org/water-stargrass-removal Link] [https://www.bentoncd.org/saving-our-river Videos]<br />
<br />
Mid-Columbia Fisheries Enhancement Group - Water Stargrass. [https://www.midcolumbiafisheries.org/yakima-river-vegetation-assessments Link]<br />
<br />
State of Washington Water Research Center Spring 2025 Seminar Series- Water Stargrass Video [https://www.youtube.com/watch?v=rEiqE0_KHkI YouTube Link]<br />
<br />
== Media Coverage ==<br />
{| class="wikitable"<br />
|+<br />
!Type<br />
!Source<br />
!Title<br />
!Date<br />
!Notes<br />
|-<br />
|News<br />
|KIMA News<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 WDFW project targets invasive aquatic plant to improve habitat in Yakima River]<br />
|September 4, 2025<br />
|<br />
|-<br />
|Blog<br />
|WDFW<br />
|[https://wdfw.medium.com/collaboration-in-the-yakima-basin-project-kicking-off-in-september-will-remove-water-stargrass-c08bc15ee9d5 Collaboration in the Yakima Basin: Project kicking off in September will remove water stargrass, improve habitat in Yakima River]<br />
|August 28, 2025<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|-<br />
|<br />
|<br />
|<br />
|<br />
|<br />
|}<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1660Lower Yakima River2025-09-05T16:38:59Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA. In addition, Phase II of the YRBWEP also provides that, as conservation measures are implemented under the conservation program and irrigation water demands are thereby reduced, the target flows will be increased by 50 cfs for each 27,000 acre-feet of diversion reduction during nonprorated water years. During those years, the target flows obtained through water conservation would be increased above 300 cfs only where irrigation return flows previously entered the Yakima River downstream of Parker gage.<br />
<br />
<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]<br />
<br />
Chandler Canal<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500 cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1659Lower Yakima River2025-09-05T15:46:11Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
<br />
<br />
'''YRBWEP and Title XII Flows'''<br />
<br />
Phase II of the YRBWEP was authorized by Title XII of the Act of October 31, 1994 (108 Stat. 4550, Public Law 103-434).<br />
<br />
One of the purposes of the YRBWEP is to implement water conservation measures to reduce out-of-stream irrigation water diversions from the Yakima River and its tributaries. Savings achieved through improvements to water delivery systems and changes in operation and management would result in more water remaining in the stream to improve flows for fish and wildlife and the reliability of the irrigation water supply.<br />
<br />
YRBWEP established target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA.<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]<br />
<br />
Chandler Canal<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500 cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1658Lower Yakima River2025-09-04T21:32:11Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
YRBWEP established new target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA.<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others. <br />
<br />
'''Stream Gages''' <br />
<br />
There are two gages in the mainstem Lower Yakima River <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]<br />
<br />
Chandler Canal<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500 cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1657Lower Yakima River2025-09-04T21:31:33Z<p>Jyeager: /* Lower River Flow/Hydrology */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
YRBWEP established new target flows for instream purposes to be maintained past the Sunnyside and Prosser Diversion Dams using criteria based on TWSA. The streamflow targets range from 300 cfs to 600 cfs, depending on the estimate of TWSA.<br />
<br />
Power subordination for fish resource protection: Power subordination occurs when power generation is reduced or shutdown, allowing the power water diversion flows to remain in the river system to protect the fishery resources or to enhance fish passage. Reclamation subordinates power production of Chandler Power Plant to various flows passing<br />
<br />
over Prosser Diversion Dam throughout the year. In the spring, the subordination target is 1,000 cfs over Prosser Dam through the end of June. During the remainder of the irrigation season, the subordination target is 450 cfs or the YRBWEP target flow, whichever is higher.<br />
<br />
Passage Flows: Flows are supported by project operations for fish movement (usually salmonids). Passage flows are flow volumes that allow fish to move un-impeded through the river system. There are three river reaches in the system with passage flow issues that are annually reviewed. Target flows for the individual river reaches are set by the Field Office Manager following consultation with SOAC and others, considering current and future water management needs. The relevant river reach in the Lower Yakima River is from Prosser Diversion Dam to Yakima River below the Chandler Power Plant return flow.<br />
<br />
Flushing/Pulse Flows: Flows are supported by project operations to facilitate the out-migration of anadromous salmonid smolts. The necessity for, magnitude, and timing of out-migration flushing/pulse flows are determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation district managers, Reclamation environmental staff, and others.<br />
<br />
Target Flows: Target flows are set for spawning, incubation, rearing, passage, and power subordination as determined by the Field Office Manager, with input or recommendations provided by SOAC, irrigation managers, and others.<br />
<br />
'''Stream Gages'''There are two gages in the mainstem Lower Yakima River, <br />
<br />
BOR Parker Stream Gage just below Prosser Dam at river mile 46.3, [https://www.usbr.gov/pn/hydromet/rtgraph.html?list=yrpw%20q&daily=yrpw%20qd see BOR Gage]<br />
<br />
USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]<br />
<br />
Chandler Canal<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500 cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
<br />
== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
<br />
See separate page on [[Water stargrass]]<br />
<br />
== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
<br />
It provides an important link for fish as an adult and juvenile migration corridor.<br />
<br />
However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
<br />
The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
<br />
<br />
<br />
For more info see the [[Yakima Delta|Yakima Delta page]].<br />
<br />
== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
<br />
'''Stream Temperature'''<br />
<br />
The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
<br />
The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
<br />
'''Sediment'''<br />
<br />
== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
<br />
Channel Complexity<br />
<br />
Large Wood<br />
<br />
Vegetation<br />
<br />
Refuge Habitat<br />
<br />
== Fish Use ==<br />
Salmon and Steelhead<br />
<br />
<br />
Bull Trout<br />
<br />
Non-Natives<br />
<br />
Predation (Piscivore and Avian)<br />
<br />
== Citations ==<br />
<references /></div>Jyeagerhttps://ybfwrb.org/yakipedia/index.php?title=Lower_Yakima_River&diff=1656Lower Yakima River2025-09-04T19:57:42Z<p>Jyeager: /* Facilities */</p>
<hr />
<div>The Lower Yakima River is approximately 51 river miles long beginning near the Yakima County/Benton County border and ending at the Columbia River.<br />
<br />
There have been numerous studies and reports detailing the Lower Yakima River with one of the more comprehensive being the Assessment of the Lower Yakima River in Benton County, Washington by the Benton County Conservation District in 2011<ref>Appel, M., R. Little, H. Wendt, and M. Nielson. Assessment of the Lower Yakima River in Benton County, Washington. Benton Conservation District, 2011. <nowiki>http://www.ybfwrb.org/Assets/Documents/Assessments/Lower_Yakima_Assessment.pdf</nowiki>.</ref>.<br />
<br />
The Lower Yakima River is a critical corridor for many species of fish including numerous salmonid species.<br />
<br />
== Geography ==<br />
=== Mainstem Reaches in this Geographic Unit ===<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain with approximately 2 miles of backwater influence on the Lower Yakima River from the McNary Dam Reservoir (Lake Wallula).<br />
# [[Prosser Reach|Prosser Reach - Yakima River Mainstem]]<br />
# [[Lower Yakima Reach - Yakima River Mainstem]]<br />
<br />
=== Tributaries to the Lower Yakima River in this Geographic Unit ===<br />
The tributaries to the Lower Yakima River all drain arid watersheds and are thought to have been intermittent prior to widespread irrigation; today they have perennial flows supported by both surface and subsurface irrigation return flows. Water quality issues are significant, with some of the highest levels of toxic contaminants found in the basin DOUBLE CHECK; significant work has been done by the irrigation districts and partners to reduce delivery of fine sediment and associated legacy toxins (DDT etc) to the Yakima from these creeks. These tributaries do support resident fish and limited numbers of anadromous fish but have generally not been considered priorities for anadromous fish restoration.<br />
<br />
# [[Spring and Snipes Creeks]] a left bank tributary that enters the Yakima River river mile 41.8; drains a mix of ag and rural residential<br />
# [[Corral Creek]] a left bank tributary that enters the Yakima River at river mile 33.5.<br />
# [[Cold Creek (Lower Yakima)|Cold Creek]] an intermittent left bank tributary that enters the Yakima River at river mile 18.8; drains a large arid area<br />
# [[Amon Creek Wasteway]] a right bank tributary at river mile 2.7 of the Yakima River; drains a rapidly urbanizing watershed in the Tri Cities; lots of work to conserve Amon Creek and adjacent lands as open space<br />
<br />
== Lower River Flow/Hydrology ==<br />
<br />
<br />
<br />
<br />
There is one gage in the Lower Yakima River, USGS stream flow monitoring at Kiona, located at river mile 30, [https://waterdata.usgs.gov/monitoring-location/USGS-12510500/#dataTypeId=continuous-00065-0&period=P7D see USGS Gage].<br />
<br />
[[Yakima River Stream Flow Monitoring|See Yakima Basin combined stream flow monitoring links page]]<br />
<br />
== Facilities ==<br />
[[Prosser Diversion Dam]]<br />
<br />
Chandler Canal<br />
<br />
Prosser Hatchery and Enumeration Facility<br />
<br />
[https://www.usbr.gov/projects/index.php?id=538 Chandler Power Plant]: Constructed and operated by the Bureau of Reclamation. the Chandler Power Plant is located 11 miles downstream from Prosser. Water is diverted at the Prosser Diversion Dam into the Chandler Canal (up to 1,500 cfs) and is delivered to the pumping and power plant 10 miles down the canal. A maximum of 334 cfs is pumped to the Kennewick Irrigation District and the rest of the water is discharged to the Yakima River at river mile 35.8. The Chandler Power Plant operates year around and us subject to power subordination agreements for fish resource protection. The power output i s marketed and sold by the Bonneville Power Administration as part of the Federal Columbia River Power System<ref>USBR. 2002. Interim Comprehensive Basin Operating Plan for the Yakima Project, Washington.</ref>.<br />
<br />
Wanawish Dam (Horn Rapids Dam)<br />
<br />
* [https://www.columbiairrigation.com/ Columbia Irrigation District]<br />
* Barker Ranch<br />
<br />
[https://www.bidwater.org/bidblog/ Benton Irrigation District]<br />
<br />
[https://lcirrig.com/ Lewis and Clark Irrigation District]<br />
<br />
[https://badgermountainirrigation.com/ Badger Mountain Irrigation District]<br />
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== Water Stargrass (''Heteranthera dubia'') ==<br />
Water stargrass is a perennial plant that has become well established in the lower 43 miles of the Yakima River, below Prosser Dam. <br />
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See separate page on [[Water stargrass]]<br />
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== Yakima Delta ==<br />
The Yakima delta and confluence is a critical link to the entire Yakima River both historically and today. The confluence was an important tribal fishing ground as noted in the Lewis and Clark Journals.<br />
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It provides an important link for fish as an adult and juvenile migration corridor.<br />
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However, much of the original floodplain/delta has been significantly developed, altered, or submerged as a result of the construction of McNary Dam downstream in the Columbia River. The reservoir now formed by McNary Dam extends nearly 2 miles up the Yakima River, changing flow and sediment deposition patterns in the delta.<br />
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The construction of the Bateman Island Causeway around 1940 further constrained the flow patterns of both the Yakima River and Columbia River in the delta.<br />
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For more info see the [[Yakima Delta|Yakima Delta page]].<br />
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== Water Quality ==<br />
Water quality concerns in the lower Yakima River include high water temperature, low dissolved oxygen, high pH, high suspended sediments, high turbidity, and high levels of toxic substances.<br />
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'''Stream Temperature'''<br />
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The lower Yakima River is known to reach levels nearing 85°F (30°C) in the summer, creating a migration barrier for salmonids.<br />
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The primary causes of high stream temperatures in the Lower Yakima River are: 1) hot air temperatures, 2) a wide, shallow river with little riparian vegetation to provide shade, 3) loss of floodplain and riparian functions due to channelization and development, and 4) low flows due to water diversions.<br />
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'''Sediment'''<br />
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== Habitat Quality ==<br />
The Lower Yakima River below Prosser Diversion Dam is generally considered a high-gradient, bedrock controlled segment with a narrow alluvial floodplain.<br />
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Channel Complexity<br />
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Large Wood<br />
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Vegetation<br />
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Refuge Habitat<br />
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== Fish Use ==<br />
Salmon and Steelhead<br />
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Bull Trout<br />
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Non-Natives<br />
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Predation (Piscivore and Avian)<br />
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== Citations ==<br />
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