Ahtanum Bull Trout Population
Overview
Ahtanum Creek enters the Yakima River in the City of Union Gap at RM 107. The mainstem extends upstream for 23 miles, at which point it splits into the North (~23 miles in length) and the South Fork (~15 miles in length). The mainstem runs through an agricultural and rural residential landscape, while the headwaters are forestland, most of which is managed as part of the Ahtanum State Forest. Currently small resident bull trout reside and spawn in all three forks; historically it is presumed to have supported a more connected population of larger fluvial bull trout.
Population Information
Population Distribution and Life History
The Ahtanum Creek drainage supports what is currently treated as a single local population of bull trout. There are known spawning areas in the upper reaches in all three forks and Shellneck Creek, a tributary to the North Fork (Figure X - MAP). Juvenile rearing occurs in the upper reaches and may extend all the way to the confluence of the forks. Adults are assumed to utilize the entire drainage as FMO habitat. It is possible that some adults migrate seasonally into the mainstem Yakima River when conditions (i.e., water temperatures) are suitable (see below), but timing of migration from FMO areas to spawning reaches is unknown.
Currently this population is considered a resident/fluvial life history type. Low stream flows due to irrigation withdrawals, thermal barriers, and habitat conditions in lower Ahtanum Creek limited migratory access to the mainstem Yakima River as early as 1880 with the construction of numerous irrigation diversions. These conditions persisted through the 2010s and are believed to have eliminated the fluvial life history, leaving only smaller headwater-resident fish in the current spawning population. Migratory conditions have improved in the last decade but there is very limited evidence of fluvial connectivity. A smolt trap has been operated by the Yakama Nation at the mouth of Ahtanum Creek since 2000 to enumerate juvenile steelhead and coho leaving the drainage (Anderson 2010). Four out-migrating adult bull trout have been caught in the trap over the 25 years of operation; the last one was in 2023 (Tim Resseguie, Pers. Comm.). All of the bull trout were 10-12 inches and captured in winter. One of the captured bull trout appeared to be smolting (figure X). If a successful fluvial life history can be reestablished, it is expected to increase the productivity and resilience of this population significantly, by increasing the fecundity of individual spawners and allowing fish to access a much broader prey base.
Natural Barriers limiting distribution
There is a waterfall at RM 2.5 on the South Fork Ahtanum Creek that is believed to be a barrier to upstream migration; whether this barrier is enough of a barrier to prevent migration and gene flow between bull trout in the South Fork and the rest of the Ahtanum watershed is uncertain. The falls are on private property and in the past, access has been denied (George Marshall, AID, pers comm). Because many of the adults in this population are small (~330mm or less), woody debris jams may be impassable barriers at low flows. These debris jams are especially common in Shellneck Creek. Surveyors have noted them as potential passage barriers during redd surveys.
Population Genetics
Genetic samples were collected from all tributaries in the Ahtanum Creek drainage and were analyzed as one population. The population was unique when compared to all the other Yakima Basin populations and did not cluster with the Naches River fluvial populations (Reiss 2003; Small et al. 2009).
In August 2012, the Yakima Basin Fish and Wildlife Recovery Board organized two nights of snorkeling in South Fork Ahtanum with the goal of collecting genetic tissue samples from bull trout (YBFWRB 2012). At this time, there had only been six samples collected in the South Fork. An additional nine bull trout were sampled during this effort.
Population Monitoring
WDFW electrofishing surveys documented the presence of bull trout in the North and Middle forks of Ahtanum Creek in 1993 (Anderson 1993). During that same year redd surveys within established index areas began in the North Fork Ahtanum Creek (including Shellneck Creek). The Yakama Nation documented bull trout in the South Fork Ahtanum Creek in 1998 and 2000 (Gullett 2001). Redd surveys were initiated on the Middle Fork Ahtanum Creek in 1996 and on the South Fork Ahtanum Creek in 2000; however, index areas were not fully established and complete surveys were not conducted on these forks until 2002 and 2001, respectively (Appendix B). The Yakama Nation conducts the surveys on the South Fork Ahtanum Creek and WDFW is the lead on the other forks.
Snorkel surveys were conducted in 2000 as part of a statewide project to predict how habitat variables affect juvenile bull trout (Dunham and Chandler 2001). Results of the survey were not reported for Ahtanum Creek, though the data was used to build habitat models. There were also snorkel surveys in 2001 in association with collection of genetic samples for Reiss (2003). In 2002 genetic samples were collected during electrofishing surveys as part of a statewide WDFW bull trout genetics baseline (Small and Martinez 2011). WDFW day and night snorkeled and electroshocked the North Fork and Shellneck Creek in 2003 as part of a project to develop a bull trout presence/absence sampling protocol (Hoffman et al. 2005). Larsen et al. (2003) examined these data in more detail with Peterson et al. (2005) providing final analysis. Various other snorkeling efforts were completed in 2007 and 2012.
Adult bull trout have been captured in two fish salvage efforts. WDFW collected 5-6 resident bull trout at the Bachelor-Hatton construction site on mainstem Ahtanum Creek in 1994 (WDFW 1996) and Scott (2010) captured two bull trout during the removal of a low dam at the North Fork Ahtanum Creek USGS gage site.
Mizell and Anderson (2010) investigated the migratory behavior of adult bull trout in the Middle and North forks of Ahtanum Creek. None of the radio tagged fish migrated outside of the Ahtanum Creek drainage. Only one fish moved below the confluence of the North and Middle forks of Ahtanum Creek.
Redd Surveys
The Ahtanum Creek population spawns primarily during the month of September. Complete redd counts were first recorded in established index areas on the North Fork Ahtanum Creek in 1993, the South Fork Ahtanum Creek in 2001, and the Middle Fork Ahtanum Creek in 2002. The index area on the North Fork is 1.9 miles long with the lower 0.5 miles of Shellneck Creek (a high elevation tributary) also surveyed. The length of the index areas for the Middle Fork and South Fork are 2.0 and 2.7 miles, respectively. Annual redd counts are presented graphically in Figure X. This population appears small and is generally getting smaller. Redd numbers have been variable over the time of record, with a high of 36 redds in 2002 and a low of four redds during the 2015 drought. The long term average is 14 redds. Redds in the South Fork Ahtanum have been variable. Two redds were recorded in 2014, one in 2019, and one in 2024. The Yakama Nation surveys the South Fork for redds 2-3 passes each year. The Middle Fork has remained the most steady spawning location, while the North Fork has been generally declining.
Other Distribution Data (eDNA, etc.)
The established redd survey reaches on the Middle and North Forks do not end at an impassable barrier. The index reaches were established in the 90's and early 2000's where the majority of the spawning occurred at that time. Little work has been done since then to understand expanded spawning or distribution upstream of the survey indices.
Population Status and Trend
The USFWS considers the Ahtanum Creek population to be depressed, decreasing, and at risk of stochastic extirpation (USFWS 1998); the WDFW rates the status of this population as critical (WDFW 2004). If future genetic analysis determines that each of the forks represents a distinct, isolated population, each of these populations would warrant a depressed or critical status.
Genetic analysis showing the Ahtanum population cluster away from other Yakima populations concurs with a lack of connectivity to the larger fluvial system (Yakima or Naches rivers).
Habitat
Habitat Overview
The area inhabited by bull trout on Ahtanum Creek ranges in elevation from 960 feet at the mouth to about 5,000 feet at the upstream end of the spawning area in the North fork (all elevations provided in this document are above mean sea level). The known spawning, and presumably primary juvenile rearing, habitat in all three forks occurs in reaches at higher elevations (4,200-5,000 feet) although it is probable that rearing habitat extends downstream to the confluence of the forks (elevation ~2,100 feet). Above the forks, land ownership consists primarily of Washington Department of Natural Resources (DNR) lands and commercial timber company holdings; Yakama Reservation lands occur south of the South fork for its entire length. Habitat conditions in the Ahtanum Creek watershed were described in detail in the Salmonid Habitat Limiting Factors Analysis for the Yakima River watershed conducted by the Washington State Conservation Commission (Haring 2001).
In the upper watershed, timber harvest (and associated roads), livestock grazing and heavy recreational use have degraded habitat conditions. Negative impacts on channel condition (pool frequency and depth, LWD presence), substrate condition (resulting from increased fine sediment load) and riparian condition have all occurred. Impacts from livestock grazing have lessened considerably over the last decade (with the exception of a broken fence allowing livestock to enter the North Fork Ahtanum Creek in 2024) but forest practices, road density and recreational impacts remain a concern. The latter is primarily associated with two DNR campgrounds located on the banks of the North Fork, which contribute to bank erosion and riparian damage, and the construction of recreational dams that impede or prevent fish passage.
In addition to the FMO habitat available in the three forks of the Ahtanum Creek, the 23 miles of the mainstem below the confluence of the North and South forks are utilized as well. Lands along the mainstem are almost entirely privately owned to the north of the creek with the Yakama Reservation to the south. The primary land use is agriculture with rural residential housing and some industrial development in the lower part of the creek. Irrigation development began in the mid-1800s and by the early 1900s there were over 100 diversions, primarily on the mainstem Ahtanum Creek. Most, if not all, were unscreened. Today there are two main irrigation projects on the creek: Ahtanum Irrigation District (AID) which serves the agricultural lands north of the creek, and the Wapato Irrigation Project (WIP) which serves the Yakama Reservation lands to the south. In addition, there are numerous smaller private pump and gravity diversions. Agricultural development has affected fish populations negatively by impacting stream processes, entraining fish, and reducing available habitat. Haring (2001) provided extensive detail regarding these effects. Since the document was published there have been significant improvements with respect to screening diversions, and reducing fish passage barriers. A a small number remain unscreened. In the early 2000s, minimum flow levels were set and there have been improvements regarding instream flow. The most significant action is the agreement with the WIP to provide a minimum flow of 10 cubic feet per second (cfs) in a 7-8 mile reach that previously dried up annually between mid-July and mid-October. These improvements notwithstanding, the mainstem remains flow depleted in the summer and early fall. The creeks floodplain has been disconnected by dikes and other channel modifications; channel condition is poor due to extensive bank erosion and the lack of LWD; riparian condition is poor due to livestock grazing, residential development and flow depletion; and summer water temperatures are unsuitable for bull trout due to riparian disturbance, floodplain disconnection, and flow depletion.
The Yakima Tributary Access & Habitat Program funded and coordinated the 2018 Ahtanum Assessment (WDFW 2018). The assessment consisted of a fish passage and diversion screening inventory in approximately 38 miles of lower Ahtanum Creek in the summer 2018. The project area focused on the private land within lower Ahtanum Creek, downstream of the DNR boundary, due to the presence of development, agricultural lands and irrigation diversions. All fish passage and diversion features encountered during the survey were described, photographed and geographic locations were recorded using GPS coordinates. A total of 59 features were encountered during the 2018 Ahtanum Creek survey. There were a total of 39 water diversions inventoried, representing 66% of all features inventoried. No full fish barriers were recorded (WDFW 2018).
Habitat Monitoring
Field Habitat Surveys
USGS reported the effects of Mount St. Helens eruptions on several watersheds, including Ahtanum Creek (Lee 1996). In the Ahtanum, metal concentrations of iron, manganese and aluminum peaked in May of 1980 due to ash accumulation in the watershed. Effects of the volcanic eruption to water chemistry were reported as "short-lived." Chesney (1998; 2000) performed a level two channel condition assessment and function of wood study in the Ahtanum system. Chesney detailed that unmanaged stands of forest resulted in significantly higher LWD and SWD density in the streams. for a long-term habitat monitoring program on DNR lands. For the Dunham and Chandler (2001) study referenced above, temperature, large wood, gradient, wetted channel width, mean depth, maximum depth, undercut banks, and substrate were measured within designated reaches.
The WDFW, through Fish Restoration and Irrigation Mitigation Program (FRIMA) funding, conducted an extensive fish passage and diversion screening survey on Ahtanum Creek from March-August 2003. This survey consisted of an inventory of all fish passage barriers and water diversions encountered within the watershed (Kohr et al. 2004). An updated fish passage and diversion study was completed in 2018 (WDFW 2018). All sites from these surveys are included in the WDFW FPDSI database. DNR maintains a separate database (RMAP) of fish passage barriers and repairs on the DNR lands in the watershed, which was updated around the same time as the WDFW inventory in 2018.
The Department of Ecology facilitated the Ahtanum Creek Watershed Restoration Program (ACWRP) which was intended to resolve water resource problems in the watershed by providing a unified program to restore stream flows and fish habitat and to improve water supply for irrigation (Ecology 2005). This resulted in a detailed plan for habitat work in the watershed but dedicated funding has not been secured.
The Washington Department of Ecology (DOE) monitored water quality at the mouth of Ahtanum Creek (Fulbright Park) in 2009. Temperature and fecal coliform exceeded state water quality standards for several months during the summer irrigation period (Ecology 2009). The U.S. Geologic Survey (USGS) has also collected water quality data from 1973-2000 at five sites on Ahtanum Creek, from the mouth to Tampico (USGS website).
The Washington Department of Agriculture monitored pollutants in lower Ahtanum Creek from 2021 -2023 and found a relatively small concentration of pesticide/herbicide (https://www.arcgis.com/apps/dashboards/9d204e71032943e1bcac43c3427e419f).
Stream Temperature Data
The Yakama Nation has collected temperature data in the Ahtanum Creek drainage (G. Morris, YN, pers comm). Nine sites along the Middle, South and North forks of Ahtanum Creek, as well as several tributaries were monitored as year-round sites from 2003-2006. There was no water temperature data collected in Ahtanum Creek from 2006 - 2011. According to the NorWeST stream temperature model, observations were submitted for various locations in the Ahtanum drainage with data from 2011. In 2024 Mid-Columbia Fisheries BTTF implemented loggers at seven monitoring sites in the north fork, middle fork, and Shellneck creeks.
Restoration Actions
The Ahtanum State Forest in managed under the terms of DNR's Habitat Conservation Plan (HCP) which is meant to assure forest management is protective of bull trout habitat; the DNR grazing lease has been managed under a grazing management plan developed by a broad-based Coordinated Resource Management team in the early 2000s, which relies on electric fencing and cattle movements to minimize the impact of grazing on bull trout. DNR has actively worked to remove fish passage barriers and address recreational impacts on its land, including work completed in partnership with Mid-Columbia Fisheries under SRFB grant 18-1650. Lower down in the watershed the North Yakima Conservation District and the Yakama Nation have completed a wide range of fish passage, screening and habitat projects primarily focused on restoring habitat for steelhead and salmon. See list below under Completed Actions.
Threats
Connectivity
Fish Passage Barriers
Threat Severity: Insignificant*
*Historically severe, now low severity.
Historically irrigation diversion-related barriers occurred through the mainstem of Ahtanum Creek and the lower end of the North and South Forks. Significant investments have been made to provide fish passage at all diversions. The most recent fish passage assessment was completed by WDFW in 2018 (WDFW 2018). It inventoried passage barriers from the mouth to the downstream extent of DNR ownership. It noted that under some flow and operational conditions the upper and lower WIP diversions may constrain passage; no other significant barriers we noted in the mainstem or lower forks. DNR has inventoried and corrected barriers on the Ahtanum State Forest. The state's FPDSI database shows a number of partial and full barriers remaining in the headwaters; these should be evaluated, and if warranted, addressed.
Redd surveyors have noted that natural debris jams, particularly in Shellneck Creek, may be passage barriers to small resident bull trout.
Entrainment
Threat Severity: Unknown, likely insignificant*
*Historically severe, now low severity.
Until recently, the high rates of entrainment into unscreened irrigation diversions on Ahtanum Creek likely created high mortality rates for migrating bull trout. The YTAHP program has made significant progress in screening all the significant irrigation diversions in the Ahtanum watershed. However, there were up to 16 non-compliant fish screens at the time of the inventory, and another 15 noted as "unknown compliance" (WDFW 2018). Entrainment issues have been largely addressed, but non compliant fish screens may be an issue. Any remaining unscreened diversions should be addressed and entrainment issues that occur when flood waters bypass the WIP diversion to enter Bachelor and Hatton creeks should be evaluated. Fish are known to travel up the ditch behind the screen at Bachelor and Hatton. Lamprey salvage occurs here at irrigation shut off. It is also known that Fullbright park has an inadequate screen and WDFW is working to fix it.
Dewatering due to flow management
Threat Severity: Unknown*
*Historically severe; current uncertain severity
Historically, irrigation diversions dried up significant portions of the mainstem Ahtanum Creek, severely constraining bull trout migrations between the Yakima River and the upper Ahtanum Creek. Non-tribal irrigation diversions have been fully adjudicated and are cut off in early July. From July on, the only significant diverter on the creek is the Wapato Irrigation Project. Yakama Nation Fisheries has a long-standing agreement with WIP to to provide a minimum flow of 10 cubic feet per second (cfs) in a 7-8 mile reach that was annually dried up between mid-July and mid-October. These improvements notwithstanding, the mainstem remains flow-depleted in the summer and early fall and bull trout passage in the mainstem is likely limited in summer and early fall due to a combination of flow and temperature conditions. The Yakama Nation Watershed Project has long term data on flow and temperature at multiple sites that can be used to evaluate passage conditions relative to time windows when bull trout migration is likely (Sept to Dec for downstream movement and May through August for upstream movements).
Land-use Issues
Forestry
Threat Severity: Unknown, likely insignificant
The Ahtanum State Forest is managed under the terms of DNR's Habitat Conservation Plan (HCP) which is meant to assure forest management is protective of bull trout habitat (https://www.dnr.wa.gov/programs-and-services/forest-practices/forest-practices-habitat-conservation-plan). Both DNR and private forestlands in the watershed have been heavily harvested in the past; recent activity has been low, with DNR completing or planning a number of sales as of 2025. One of the sale units is in the North Fork Ahtanum drainage and is certified under the Sustainable Forestry Initiative. The sale is upland of the main stem of the the North fork. To date the Ahtanum watershed has not had large fires; a summary of forest restoration needs and fire risks is available here: https://www.dnr.wa.gov/sites/default/files/publications/rp_2018_forest_health_assessment_treatment_framework_report_ahtanum.pdf?n9nx23
Agriculture and Grazing
Threat Severity: Moderate
Grazing occurs both on WA DNR land and on private land further down in the watershed. The DNR grazing lease has been managed under a grazing management plan developed by a broad-based Coordinated Resource Management team in the early 2000s, which relies on electric fencing and cattle movements to minimize the impact of grazing on bull trout; grazing also occurs in the upper watershed on lands owned by the Ahtanum Irrigation District.
In the lower end of the forks and the mainstem, grazing impacts riparian conditions on private land; the Yakama Nation and the North Yakima Conservation District have both worked with landowners to create riparian buffers and managed grazing plans. Agriculture has also impacted bull trout habitat through water diversions (see the flow and entrainment threat sections) and through habitat simplification associated with floodplain development for agriculture.
In 2024, redd surveyors on the North Fork of Ahtanum Creek in Ahtanum State Forest observed cattle within the stream, and riparian area in the spawning index for bull trout. DNR was contacted, and they noted there was a fence breach which would be taken care of. Collaboration with DNR to ensure cattle exclusion during critical bull trout spawning periods should be ongoing.
Recreation
Threat Severity: Unknown
DNR's Ahtanum State Forest is popular for OHV riding, horseback riding, hiking, bird watching, hunting and camping. The largest threats from recreation occur in the form of rock dam construction in the upper (spawning) areas of the Middle Fork and North Fork. Tree phones campground was historically an area of high impact to the creek with rock dam construction and people driving in the stream. Mid-Columbia Fisheries installed buck-and-rail fencing to keep vehicles away from the creek. Rock dams in this location have also decreased due to low gradient nature of the stream in this area and the majority of the sediment being pea gravel or smaller. Large rocks to build dams are less common. However, the North Fork Ahtanum at Snow Cabin campground sees heavy recreation and is a frequent location for the BTTF to find and dismantle rock dams. Other access sites near the spawning indices haven't been a large issue in the past. More exploration near the confluence of the forks and downstream should occur to mitigate any fish passage barriers caused by recreators.
Roads and Development
Threat Severity: Moderate
DNR and private landowner have extensive forest road networks in the upper watershed; both DNR and the larger timberland owners have implemented road improvement plans to reduce sediment impacts and remove passage barriers. Road crossings in the lower watershed are not known to create passage issues; road generated stormwater may impact water quality in the lower reaches of the mainstem.
Mining
Threat Severity: Not applicable
The only known mining activity or legacy in the watershed is associated with upland rock and gravel pits.
Other
Ecological Interactions
Brook Trout
Threat Severity: Insignificant
As of 2025, brook trout have not been found in the Ahtanum watershed.
Other Invasive Species
Threat Severity: Insignificant
No other invasive fish species are known to be present in the Ahtanum watershed.
Diminished Prey Base
Threat Severity: Significant
The current headwater resident bull trout populations make use of only a limited amount of cold, relatively low productivity habitat largely upstream of the extent of current and presumed historic anadromous fish use. Restoring the fluvial life history and associated use of downstream FMO habitat would greatly increase the productivity of the population; restoration of increased anadromous production in the lower forks and the mainstem would only further improve the prey base.
Disease
Threat Severity: Unknown, likely insignificant
No disease issues are known in the Ahtanum watershed.
Water Quantity and Quality
Flow issues/dewatering
Threat Severity: Unknown, likely significant
See above under Dewatering due to flow management for a summary of flow issues in the mainstem of Ahtanum Creek. No significant dewatering issues have been observed in the upstream spawning and rearing reaches of Ahtanum Creek.
Current and Future Observed and Modelled Temperature Conditions
Threat Severity: Significant in FMO
Ahtanum Creek headwaters have maintained cold temperatures in recent years and the NorWest temperature model shows the upper reaches Ahtanum Creek to be relatively resilient to warming due largely to their high elevation; however, temperature monitoring in 2024 showed similar results to the NorWest (https://usfs.maps.arcgis.com/apps/webappviewer/index.html?id=bf3ff38068964700a1f278eb9a940dce) projected temperatures for 2040. See the Stream Temperature section above for more details. High summer temperatures combined with flow limitations to create seasonal migration bottlenecks in mainstem Ahtanum Creek (see above under passage barriers).
Other changes in hydrology
Threat: Moderate
As a relatively small stream system, Ahtanum Creek may see baseflow flow impacts from forest management, future fires, and climate change.
Fisheries Impacts
Angling Regulations/Fisheries Use/Poaching (Recreational)
Threat Severity: Unknown
The primary spawning and rearing reaches of the Middle and North Forks of Ahtanum Creek are closed to fishing (from the A2000 Spur Rd. Bridge in NE 1/4 of section 34 upstream to the A2800 Rd. Bridge at Tree Phones Campground (about 3.5 miles) on the Middle Fork) and from Grey Rock Trailhead Bridge crossing to Shellneck Creek (about 1.7 miles) on the North Fork). The rest of the mainstem and the North and Middle Forks are open to fishing; the level of use and the incidence of bull trout bycatch is unknown. Fisheries on the South Fork are managed by the Yakima Nation. The Bull Trout Task Force has never observed people fishing in Ahtanum Creek.
Management/Monitoring (Research)
Threat Severity: Insignificant
A snorkel survey of the South Fork in 2012 culminated in the capture and genetic sampling of nine individual bull trout. Other than that, and annual redd surveys, little work has been done to capture and monitor bull trout in the Ahtanum watershed.
Other Threats
Low Population Resiliency
HIGH- isolated, low numbers, limited to small core habitat area
Climate Change
Other
Summary of Primary Limiting Factors and Threats
The highest severity threats to this population are low abundance, diminished flows (lack of fluvial life history), lack of prey base, and recreation. Although there have been improvements to summer base flows, and diversions have been screened, the ongoing diversion of water to nearby farms will exacerbate low flow conditions and increased water temperature in the mainstem Ahtanum Creek. With the largest threats occurring in FMO habitat, the prospect for restoring a fluvial life history is still a challenge. A lack of prey base and limited spawning and rearing habitat make increasing population numbers a challenge, unless FMO habitat can be fully utilized. Over the past few decades, grazing has not been a significant threat, however a fence breach in 2024 into the spawning index, during spawning season emphasizes the need for ongoing compliance and fence monitoring. Recreation, particularly rock dam construction, may be more threatening to this population than others due to the small body size of spawning-age fish. However, there has been a notable decrease in rock dams over the past several years and campground improvements have reduced impacts to the streams. Although temperature still remains suitable year-round in the majority of the North and Middle forks, 2024 (a drought year) data tracked with NorWest temperature projections for 2040.
The threat of entrainment has been substantially reduced with the addition of fish screens on all the major diversions from Ahtanum Creek. Natural dewatering, brook trout, mining, disease, and forest harvest are not considered threats at this time.
Recovery Strategy
Population-level Recovery Strategy
This population has been identified as a high priority “Action” population (see Prioritization of Actions in 2012 BTAP). The highest priority recovery actions are those that improve habitat and access to habitat in the upper spawning and rearing reaches and those that restore instream flow and reduce entrainment in the lower FMO reaches. Some of the threats to the Ahtanum Creek bull trout population have been mitigated with road closures and recreation improvements made by DNR. It is critical to work with staff at the DNR to ensure ongoing management supports bull trout recovery. As of 2025, screening of all the major diversions in FMO habitat has greatly reduced the potential of entrainment. Further protection and restoration of downstream FMO habitat will involve partnerships with private landowners. This is an area where habitat improvements are currently being completed based on their importance for anadromous species. Addressing the current Low Abundance threat by continued population monitoring will be critical, as will understanding the movement patterns between forks. This is a candidate population for evaluating the feasibility of supplementation. Outreach is a priority in order to document angling pressures and to educate anglers, recreationists, and landowners throughout the watershed. The Broad Scale actions that apply to the Ahtanum Creek populations include: Restore Healthy Salmon Populations.
Monitoring Needs/Key Questions
Is angling a threat?
Actions
Future link/ iframe to PowerApp will go in this section.
Completed Actions
- Screened nine unscreened gravity diversions and side channel construction (2001-2008).
- Riparian exclusion fence constructed within grazing allotment in spawning areas of the North Fork Ahtanum Creek in 2004.
- Cattle grazing allotment in Middle Fork Ahtanum Creek not renewed in 2008.
- Passage barrier removed at North Fork Gaging Station in 2010 (YTAHP).
- Herke fish screen (SRFB project 10-1764). (Project was funded in 2010 and should be completed in Fall 2012.)
- The North Yakima Conservation District screened three unscreened (non-compliant) pump diversions in 2005.
- Agreement between Yakama Nation and principle irrigators to maintain a minimum of 10 cubic feet per second (cfs) instream flows.
- Fishing regulations have been implemented to protect bull trout in Ahtanum Creek (see Appendix F).
Recommended Actions
Relevant Multiple Population Actions
Multiple Populations #1: Outreach on bull trout conservation issues (landowners, recreationists, anglers, school groups, and others).
Multiple Populations #2: Continue redd surveys within the established index areas of all forks to monitor long-term abundance trends.
Multiple Populations #3: Continue temperature monitoring throughout Ahtanum Creek drainage, expanding as necessary.
Multiple Populations #4: Evaluate supplementation (see Appendix D).
Multiple Populations #5: Carcass analog placement if pilot studies demonstrate success.
Multiple Populations #6: Monitor for recreational dams on an annual basis and remove as necessary.
Ahtanum Creek Actions
- Ahtanum Creek #1: Riparian and Floodplain Restoration in Spawning and Rearing Reaches
- Ahtanum Creek #2: Forest Management
- Ahtanum Creek #3: Manage Roads and Trails to Minimize Impacts to Bull Trout
- Ahtanum Creek #4: Habitat Monitoring
- Ahtanum Creek #5: Evaluate Population Status and Distribution
- Ahtanum Creek #6: Increase Instream Flow in Lower Ahtanum Creek
- Ahtanum Creek #7: Monitor Habitat and Develop Projects in Mainstem Ahtanum
- Ahtanum Creek #8: Screen All Diversions
- Ahtanum Creek #9: Manage and Restore Campgrounds
- Ahtanum Creek #10: Education and Outreach
- Ahtanum Creek #11: Grazing Management
- Ahtanum Creek #12: Manage Bull Trout Access to Bachelor and Hatton Creeks
- Ahtanum Creek #13: Hatchery Supplementation
Actions in the Yakima Steelhead Recovery Plan that benefit this population
(Yakima Basin Fish & Wildlife Recovery Board 2009)
Naches River Action #24: Protect instream flow improvements in Ahtanum Creek
Naches River Action #25: Develop off-channel storage in Ahtanum Creek
Naches River Action #26: Minimize irrigation conveyance loss in Ahtanum Creek
Naches River Action #27: Ahtanum Creek floodplain and side channel restoration
Naches River Action #28: Protect Ahtanum Creek riparian areas to lessen developmental impacts
Naches River Action #29: Reduce livestock impacts on Ahtanum Creek riparian areas
Update Notes
2012 BTAP text copied into Yakipedia and edited to match new format in June 2025 by Aimee Taylor. ADD LINK TO 2012 BTAP pdf placemark
Additional edits proposed by Alex Conley, Aimee Taylor and Ahtanum Creek Population small group. Reviewed, and updated and approved by BTWG in September 2025.
Specific detail on out of cycle updates: