North Fork Tieton Bull Trout Population

Overview

The North Fork Tieton River population is one of three distinct populations in the Rimrock Population Group. The North Fork Tieton River flows into Rimrock Reservoir at its western end. The river originates in the Goat Rocks Wilderness Area and flows for about 10.5 miles before entering Clear Lake, a small (5500 acre-foot) impoundment that was created when Clear Creek Dam was constructed in 1914. The entire watershed is in the Okanogan-Wenatchee National Forest; most of the watershed is in the Goat Rocks Wilderness Area (the boundary is approximately five miles upstream of Clear Lake). Several small tributary streams enter the North Fork Tieton River above Clear Lake, the largest being Scatter Creek. Clear Creek, once the most significant tributary of the North Fork Tieton River, now flows into Clear Lake from the west. Below Clear Creek Dam, the North Fork Tieton River flows for about 0.7 mile before entering Rimrock Reservoir (at high pool). The North Fork Tieton River is only open to angling from Memorial Day weekend until August 15th each year to protect spawning bull trout.

Population Information

Population Distribution and Life History

Figure 1. North Fork Tieton subwatershed. update spawning survey reach.  it appears to start much further downstream than it actually does.  also, it is unclear what the dark orange highlight around the reach between scatter creek camp and half way to the barrier falls is trying to designate.  Seems like it should just be FMO and known presence.  why is there a separate "known spawning" designation in light yellow in addition to the "spawning survey" designation in red?

The North Fork Tieton River population was "recently discovered” although catch records from the 1950s documented the presence of adult bull trout (referred to at the time as Dolly Varden) in Clear Lake and biologists from CWU found a single adult bull trout above the lake in 1996 (Craig 1996). However, there was no clear indication that a spawning population inhabited the North Fork Tieton River until 2004. Reference back to helicopter transport into clear lake as possibible source of current population? During the fall of that year, a fish census was conducted in the river that documented the presence of 14 bull trout including seven juveniles (<199 mm TL), five that were considered subadults (200-299 mm TL), and two large (>500 mm TL) adults (USFWS 2004). In addition, spawning activity was confirmed with the discovery of a single redd and a couple of large adults observed about 0.6 mile below the waterfall. As a result of the data collected and observations made in 2004, a population of bull trout was officially recognized in the North Fork Tieton River (Thomas 2005). This population is adfluvial, based on the large size and documented migration of tagged fish past USFWS PIT antennas above Clear Lake beginning in 2012.

Although data are limited, it appears that the majority of spawning activity occurs above the wilderness boundary located about five miles upstream of Clear Lake with most of that occurring in the reach extending from the waterfall downstream for approximately two miles (Figure 1). Since 2008, spawning in Hellbender Creek, a tributary which enters the river from the west in this two-mile reach, has been well documented. Hellbender Creek is now an established redd survey index and is surveyed yearly. Juvenile rearing occurs throughout the reach above Clear Lake, as first noted by Thomas (2005).

As of the 2012 BTAP, timing of migration into the North Fork Tieton River was largely unknown. However, a multi-year study beginning in 2012 addressed this question as well as fish passage conditions at Clear Creek Dam. Results showed that most bull trout migrate upstream to the spawning grounds starting in May. The majority of fish tagged in this study were detected moving upstream in June or July with a few migrating in August. The fish were detected going back downstream between mid September and early October (Thomas and Monk 2016).

The primary FMO habitat for adults and subadults is Clear Lake (see discussion under Population Monitoring) although many fish pass downstream through the Clear Creek Dam spillway channel or outlet works. In 1992, the USBR constructed two ladders in the steep bedrock spillway channel adjacent to the dam; the upper ladder is a pool and weir that appeared to be functional but the lower one (a denil ladder) was poorly engineered and has had persistent problems with bedload accumulation.

During the Clear Creek Dam Fish Passage Assessment from 2012-2015, it was discovered that the fish ladder constructed in the spillway channel adjacent to the dam was not being used by bull trout for two main reasons. First, bull trout were drawn to the base of the dam by cooler hypolimnetic water releases from Clear Lake as opposed to the warmer surface water flowing down the spillway channel. Second, the fish ladder was not built using fish passage criteria and was ultimately considered too steep and turbulent for fish to ascend it even if water temperatures are suitable (Thomas and Monk 2016). In 2016, the work shifted to trap and haul where bull trout are collected at the base of the dam, PIT tagged, and then genetically assigned to their population of origin and evaluated to determine whether they have hybridized with brook trout. Based on the results of the genetic tests, bull trout are either transported upstream and released into Clear Lake (North Fork Tieton River origin), released downstream of the stilling basin (Indian Creek or South Fork Tieton River origin), or euthanized (brook trout/bull trout hybrid). Since 2015, 141 bull trout identified as North Fork Tieton fish have been transported above the dam and released into Clear Lake. An additional 112 bull trout identified as South Fork Tieton River or Indian Creek fish that also migrated to the base of the dam, were captured and released downstream of the stilling basin while 15 fish identified as brook trout/bull trout hybrids have been euthanized. Trap and haul and PIT tag monitoring is ongoing, with the most recent report published in 2022 (Beebe et al. 2024).

Natural Barriers limiting distribution

Figure 2. North Fork Tieton Falls

A waterfall about nine miles upstream of Clear Lake at 46.535693, -121.390993 presents an impassable barrier for migratory fish (Figure 2).

Population Genetics

Six genetic samples were collected from bull trout juveniles during the 2004 study (USFWS 2004). Efforts to collect additional samples were constrained by turbidity issues until 2010 when enough genetic samples (30+) were collected to analyze the uniqueness of this population. Results indicate that this population is genetically distinct from all other populations in the Yakima Basin including the other adfluvial populations residing in Rimrock Reservoir (Indian Creek and the South Fork Tieton River) (Small and Martinez 2011). The construction of Tieton Dam in 1925 eliminated upstream passage for Naches fluvial fish, but entrainment of North Fork Tieton River bull trout may be contributing to one way gene exchange downstream of the dam.

There have been a number of confirmed brook trout x bull trout hybrids collected over the years. Small and Martinez 2011 noted that brook trout alleles were detected at a low frequency in the NF Tieton specimens, even though some fish were noted as potential hybrids by field biologists. From 2012-2024, the U.S. Fish and Wildlife Service has identified 15 hybrids during trap and haul work. Seven of these fish were introgressed with North Fork Tieton River origin fish. Hybridization and introgression with brook trout should be studied further in this population.

See information under population genetics section of Rimrock Reservoir Populations Page

Population Monitoring

Compared with other bull trout populations in the Yakima Basin, the monitoring history for the North Fork Tieton River population is fairly recent. In 1993, the Forest Service captured a juvenile bull trout in a minnow trap on the margins of Clear Lake (USFS 1993b). The first organized investigation of bull trout in the North Fork Tieton River appears to have occurred in 1994 when Central Washington University coordinated with WDFW to monitor the effectiveness of the fish ladders constructed in the spillway channel of Clear Creek Dam two years prior. No bull trout were observed in the ladders but nine adult bull trout were captured and tagged below the base of the dam. It is assumed that these fish were attempting to find a migration route upstream and would thus have belonged to the North Fork Tieton River population. Two years later an adult bull trout was observed in the North Fork Tieton River about six miles above Clear Lake during a snorkel survey (Craig 1996). In 2004, a fish census survey conducted cooperatively by the USFWS and the Forest Service confirmed a spawning population existed in the North Fork Tieton River (USFWS 2004). The details of this monitoring effort were discussed above in the Population Distribution and Life History section.

In 2010, snorkel surveys coordinated by the USFWS were successful in collecting enough genetic samples from juvenile bull trout to supplement those collected previously and enabled an analysis of the genetic uniqueness of the North Fork Tieton River bull trout population (Small and Martinez 2011).

WDFW radio-tracked five adult bull trout captured and tagged in the North Fork Tieton River below Clear Creek Dam in July 2005. These fish all migrated downstream to Rimrock Reservoir by late fall to overwinter and returned to the area near the mouth of the North Fork by early June the next year. Only one eventually entered the river but did not attempt to ascend the ladders in the spillway channel (Mizell and Anderson 2008). Interestingly, only one fish that was collected below Clear Creek Dam in 2005 was genetically assigned to the North Fork Tieton River population (Small and Martinez 2011). Apparently the reach below the dam is used by all Rimrock Reservoir populations, not just North Fork Tieton River adults intending to migrate above the dam to spawn.

The stilling basin and short river section below the dam are monitored by the USFWS via PIT antennas and their trap and haul program. PIT antennas have been in place in the outlet channel below Clear Creek Dam since 2016 and in the upper and lower sections of the fish ladder since 2012 and 2014 respectively. These antennas operate year round. It remains true that bull trout from all the Rimrock Reservoir populations use this area and congregate below Clear Creek Dam. Since 2015, 141 bull trout identified as North Fork Tieton fish have been transported above the dam and released into Clear Lake.

The USFWS also operates two PIT antennas in the North Fork Tieton River above Clear Lake. The lower antenna is about 0.75 miles upstream from the confluence with Clear Lake and the upper antenna is about 1 mile downstream of the wilderness boundary. These monitoring generally sites operate from May-November when a lack of sunlight ends operation.

As with the other two Rimrock Reservoir populations, North Fork Tieton River bull trout are subject to entrainment through the outlet works of Tieton Dam. The results of studies investigating the entrainment of Rimrock Reservoir bull trout through the outlet works of Tieton Dam can be found on the Rimrock FMO page. Also discussed was the collection of 37 bull trout from the stilling basin directly below Tieton Dam during a fish salvage effort in 2005 and the subsequent analysis of genetic samples taken from those fish. This analysis revealed that two of the bull trout captured in the stilling basin below the dam assigned to the North Fork Tieton River population (Small et al. 2009). This provides further evidence that the North Fork Tieton River population uses Rimrock Reservoir as FMO habitat.

Redd Surveys

The spawning period for the North Fork Tieton River population occurs primarily during the month of September but can extend through October. Fish typically begin moving into North Fork Tieton River above Clear Lake in late June and return to Clear Lake by early November, presumably after spawning (Beebe et al. 2024). Problems have been encountered in attempting to annually conduct complete redd surveys in the North Fork Tieton River. The river is glacial-fed and is usually milky with glacial flour until late in the summer. Its hydrology is “flashy” and river discharge quickly changes from stable and clear to high and turbid after fall rains or high daytime temperatures, both of which are common during the bull trout spawning period. This results not only in difficult survey conditions but also in conditions in which redds become undetectable if an event occurs before or between surveys. Although the first redd was observed in the North Fork in 2004, a complete survey was not accomplished until 2007 for the reasons just described. The surveys conducted in 2009 and 2010 were incomplete. Dewatering has been observed in the upstream spawning survey index in recent years (see Habitat Overview).

Figure 3. North Fork Tieton Annual Redd Counts 2004-2024. There was no survey in 2018 due to the Miriam wildfire.

Surveys are conducted in an index reach approximately 2.3 miles in length, which ends at the barrier waterfall. Included in this index area since 2008 is an unnamed tributary, locally referred to as Hellbender Creek. For logistical reasons (i.e., access and hydrologic timing), just two survey passes are typically attempted annually. During the first year of redd surveys 37 redds were observed and Hellbender Creek was not included. Redd counts have ranged from the high 30s to single digits over the past 20 years, with a record count of 39 in 2017 (Figure 3). The yearly average is around 17 redds. There was no survey in 2018 due to the Miriam wildfire.

An exploratory redd survey in 2023 documented 5 bull trout redds below the wilderness boundary, in the vicinity of the Scatter Creek Trailhead. This information may warrant additional exploratory surveys in the future to determine if this is now a primary spawning location.

Population Status and Trend

The USFWS estimates survival probability using PIT tag detections from antenna sites in the upper and lower North Fork Tieton River. Since 2013, annual survival probability has ranged from 0.60 - 0.70 (mean = 0.64; Beebe et al 2024). Mean survival probabilities have shown variability from year to year with the last three years (2021-2023) below the mean. Currently the USFWS has been unable to develop survival estimates in other spawning tributaries that would allow for relative comparisons to other Yakima Basin populations. Although PIT antennas are in place, operations at several antenna sites have been limited by high flow events that have destroyed equipment, vandalism, dewatering, and other connectivity issues. These issues often result in too few tagged fish being detected on upper antenna locations.

At the time of the 2012 BTAP, the status of this population had not been rated by either the WDFW or the USFWS. Based only on redd counts to-date, it appears to be depressed.

Habitat

Habitat Overview

The North Fork Tieton River is one of the higher elevation streams inhabited by bull trout in the Yakima Basin. Elevations range from 3,000 feet where it enters Clear Lake to about 4,000 feet at the impassable waterfall located just over nine miles upstream. As mentioned previously, approximately four miles of the river is in the Goat Rocks Wilderness with the lower five miles flowing through the Okanogan-Wenatchee National Forest. A Forest Service road (1207) parallels the river for these five miles but is rarely close to it with dense forest separating the two. The main human activity in the watershed is recreation.

In short, the North Fork Tieton River is undisturbed above the wilderness boundary and for the most part below it as well. The floodplain is connected and properly functioning, the riparian corridor is healthy, LWD is plentiful, and water quality is excellent (USFS 1998). Pool frequency did not meet Forest Plan standards but it was noted that the evaluation was limited to full channel pools and that smaller pools (not evaluated) were prevalent in riffle habitat. The North Fork Tieton River is a relatively sediment-rich river. This is likely due to the fact that it received a great deal of fine volcanic material during the 1980 eruption of Mount St. Helens and because its waters are of glacial origin. Much less fine sediment is present in the upstream reaches, which may explain why the majority of the spawning activity and juvenile fish observed to date have occurred above the wilderness boundary.

The Miriam wildfire started on July 28, 2018 and burned through 5,400 acres of the North Fork Tieton watershed culminating around September 18th, 2018. The fire primarily burned upland of the riparian corridor with overall low soil burn severity.

In recent years (2022, 2023, 2024), dewatering has been observed in the two mile reach below the barrier falls during low flow periods. Observations from local field biologists have noted frequent changes in channel location over the past 20 years. Channel shifts may contribute to subsurface flow and dewatering.

Habitat Monitoring

Field Habitat Surveys

The Forest Service completed a habitat survey using Hankin and Reeves protocol on the North Fork Tieton River in 1998 (Hankin and Reeves 1988; USFS 1998). In this survey, data were collected on pool/riffle frequency, riparian and channel condition, substrate, LWD, and temperature.

Stream Temperature Data

Figure 4. Observed temperatures in the North Fork Tieton River about Clear Lake in 2024. A configuration error caused upstream loggers to stop logging in July.

The North Fork Tieton River was monitored for temperature via thermographs deployed at the FS 1200 road crossing during the summer low flow period in 7 out of 11 years from 1997-2007 (USFS 2011a). A thermograph was also deployed at the confluence of Scatter Creek in 1997. An observation in the 1998 stream survey report noted that the the stream temperature varied approximately 10 F during a 24 hour period during the monitoring period from July through September (USFS 1998). They also noted that some tributaries had higher temperatures than the mainstem. Temperature data from 2007- 2018 is a monitoring gap. USFWS started monitoring temperature again in 2018 at its two PIT antennas upstream of Clear Lake, downstream of Clear Creek Dam in the fish ladder, and in the outlet channel of Clear Creek Dam. The USFWS also deployed thermograph strings in the Clear Creek Dam forebay to help characterize temperature patterns with respect to bull trout movement in and around the dam. In 2024, Bull Trout Task Force contributed additional temperature loggers in Hellbender Creek, and the upper 2.3 miles of spawning habitat (one logger below the falls, one logger in the index downstream of Hellbender Creek confluence)

Clear Creek water temperature was monitored in 2023 by USFS and was consistently colder than 8 C from June through October.

Threats

Connectivity

Fish Passage Barriers

Threat Severity: Significant

During the Clear Creek Dam Fish Passage Assessment from 2012-2015, it was discovered that the fish ladder constructed in the spillway channel adjacent to the dam was not being used by bull trout. With the data to reflect significant entrainment and lack of adequate passage at Clear Creek Dam, USBR has funding to address the passage issue and construction of a functional fish ladder is scheduled for 2025. The new fish ladder will reconnect Clear Lake and Rimrock Reservoir to migrating bull trout.

Tieton Dam blocks upstream passage into Rimrock Reservoir, leaving the North Fork Tieton River only accessible to adfluvial bull trout that reside in Clear Lake or are passed from Rimrock Reservoir via trap and haul. See the Rimrock Reservoir FMO page for more details.

Entrainment

Threat Severity: Significant

No irrigation diversions or other sources of entrainment are located on the North Fork Tieton River. NF Tieton fish are subjected to downstream entrainment through Clear Creek Dam and Tieton Dam.

The USFWS has identified 141 bull trout as North Fork Tieton fish from Trap and Haul below Clear Creek Dam. Bull trout are either entrained or go down the spillway fish ladder at Clear Creek Dam. Some injury and mortality has been noted to fish discovered below the dam, potentially trauma from entrainment.

The issues related to entrainment at Tieton Dam are addressed in the Rimrock FMO section.

Dewatering due to flow management

Threat Severity: Unknown, but likely insignificant

It is unlikely that the North Fork Tieton River dewaters as it crosses the reservoir bed, but it has not been monitored.

Land-use Issues

Forestry

Threat Severity: Unknown, but likely insignificant

Timber harvest occurred in the past but well upslope of the river. The area is now designated as Late Successional Reserve and will receive very little future harvest. Road density in the drainage is low.

Agriculture and Grazing

Threat Severity: Insignificant

Livestock grazing does not occur in the North Fork Tieton watershed.

Recreation

Threat Severity: Unknown

Recreation near the NF Tieton River upstream of Clear Lake is primarily hiking and horseback riding on trails that are not directly on the river. There are no established campgrounds, but there are several dispersed campsites with hard-to-notice access roads off the main road USFS 1207. Recreational rock dams have been found by the Bull Trout Task Force at some of these locations.

Clear Lake is a popular camping and fishing location for residents of the Yakima Valley, but most campers do not venture far from the established camping areas. Trash is frequently found in and along the North Fork Tieton in the heavy-use area below Clear Creek Dam.

Recreational mining occurs, but hasn't been identified as a problem. Some people go rock hounding for thundereggs.

Roads and Development

Threat Severity: Unknown, but likely insignificant

A Forest Service road (1207) parallels the river for five miles but is rarely close to it, with thick forest separating the two. There are a number of developed camping areas around Clear Lake including USFS Clear Lake Campground and day use area, Camp Prime Time, Camp Dudley, Grace Brethren Church Camp and Camp Zarahemla.

Mining

Threat Severity: Insignificant

In a 1998 stream survey report, the author notes that it's possible areas within the stream banks and adjacent to the stream were mined. Mining was common on Naches Ranger District lands. Starting in the mid 1800's gold, silver, zinc and molybdenum mines were prospected. However, there is no written history of mineral resources or commercial mining in the NF Tieton watershed.

Other

No other land use issues have been identified.

Ecological Interactions

Brook Trout

Threat Severity: Unknown, but likely significant

Brook trout are known to be abundant. In a 2004 snorkel over a total of 7 miles from Clear Lake to the barrier falls, 621 brook trout were observed (USFWS 2004). There have also been recent observations of Brook trout during bull trout spawning surveys (2024 redd observational data). From 2012-2024, the U.S. Fish and Wildlife Service has identified 15 hybrids during trap and haul work. Seven of these fish were introgressed with North Fork Tieton River origin fish. Hybridization and introgression with brook trout should be studied further in this population.

Clear Creek was once a tributary to North Fork Tieton before Clear Lake was impounded. Clear Creek is known to have many of brook trout but also has relatively cold water and excellent habitat for bull trout. Eradication of brook trout would help potential efforts to re-establish bull trout in Clear Creek. Eradication might be challenging due to the naturally producing populations of brook trout in Dog and Leech lakes, which are headwaters to Clear Creek. It is unknown how many brook trout survive the 228 foot drop over Clear Creek Falls.

Other Invasive Species

Threat Severity: Insignificant

Other invasive species of fish have not been observed.

Diminished Prey Base

Threat Severity: Unknown

North Fork Tieton bull trout would once have had access to juvenile chinook, steelhead and coho salmon that spawned throughout the Tieton and Naches watersheds. This food source was eliminated when Tieton Dam was completed in 1925. However, the reservoir created by the dam, Rimrock Reservoir, was historically stocked with kokanee, which now reproduce naturally, and has proven productive enough to support relatively large populations of large adfluvial bull trout in the Lake's tributaries (see FMO section for more information). North Fork Tieton River bull trout use Rimrock Reservoir as FMO habitat. More information is needed to determine if extensive draw-downs on Rimrock Reservoir have a substantial effect on prey base.

Clear Lake is frequently stocked with rainbow trout (~20,000 / year) by WDFW. The extent of predation on stocked trout by bull trout is unknown.

Disease

Threat Severity: insignificant

Disease issues have not been noted for the North Fork Tieton River population.

Other

As the North Fork Tieton River crosses the reservoir bed at low pool, there is a lack of cover and habitat refuge from predators.

Water Quantity and Quality

Flow issues/dewatering

Threat Severity: Unknown, likely significant

Dewatering in the 2 miles downstream of the barrier falls has been noted every year from 2022-2024. Dewatering in this location may preclude spawning in some of the best spawning gravel in the whole river. Stranding pools are also a concern.

Climate change may impact flows through the melting of glaciers and permanent snowfields in the headwaters.

Current and modeled future temperature conditions

Threat Severity: Unknown

NorWest Stream Temperature model projects the North Fork Tieton River to remain less than 12 C mean August temperature.

Fisheries Impacts

Angling Regulations/Fisheries Use/Poaching (Recreational Fishing)

Threat Severity: Unknown, but likely significant

In 2011, the Bull Trout Task Force conducted creel surveys in Clear Lake during the summer months. Fifty five anglers were interviewed and no bull trout were reported by any of these anglers (WDFW 2011). Previous creel surveys and observations by WDFW biologists during annual fishing derbies support this evidence that bull trout are not commonly caught in Clear Lake, despite heavy fishing pressure throughout the summer season (E. Anderson, WDFW, pers comm). In 2023 the Bull Trout Task Force talked with an angler who reported catching a bull trout in Clear Lake and released it based on informational signage that helps anglers identify bull trout. BTTF notes that a small percentage of the anglers communicated with at Clear Lake know about bull trout and can confidently identify them. As of 2023, BTTF has started leaving identification cards for Spanish and English speakers at Clear Lake boat launch and day use areas. Language barriers have been identified as a common issue with outreach efforts in this area.

The BTTF regularly visits the area downstream of the dam for outreach during the summer season. Many anglers report catching bull trout in the river between the dam and Rimrock Reservoir. It is unclear how many bull trout are released unharmed vs illegally harvested. USFWS trap and haul has recently expanded to include this river area downstream of the dam. Signage that helps anglers understand closed fishing areas and how to identify bull trout are posted yearly.

Regulations have been implemented in the North Fork Tieton River in an attempt to protect bull trout. The river is open to fishing from Memorial Day weekend through August 15th, including the section flowing through the reservoir bed.

Management/Monitoring (Research)

Threat Severity: Unknown

Since 2015, 141 bull trout identified as North Fork Tieton fish have been transported above the dam and released into Clear Lake during USFWS Trap and Haul at Clear Creek Dam. Fish are captured using hook and line, or tangle nets.

Other Threats

Low Population Resiliency

Climate Change

Summary of Primary Limiting Factors

The highest severity threats to the North Fork Tieton River population are the lack of connectivity resulting from the construction of Tieton and Clear Creek dams. Also resulting from lack of passage at Tieton Dam are the threats of entrainment and lack of marine derived nutrients and/or anadromous salmonids as a prey base. Low abundance and unstable redd numbers are possibly the result of passage problems at Clear Creek Dam, which should be remedied with the new fish ladder. Other threats to this population include angling mortality in Rimrock Reservoir, and in the camping area below Clear Creek Dam. Introgression with brook trout is an emerging concern. Brook trout have been observed all the way to the upstream passage barrier, and have been documented spawning. Clear Creek, a tributary that flows directly into Clear Lake has a large population of brook trout. Dewatering due to drought and climate change has been documented in the 2.3 mile spawning survey index below the barrier falls each year from 2022 through 2024. In low precipitation years, this dewatering may affect spawning and rearing and strand adult fish.

Recovery Strategy

Population-level Recovery Strategy

This population has been identified as a high priority “Action” population. The highest priority actions are the broad-scale action of Passage at Tieton Dam and the immediate population-scale action of improving passage at Clear Creek Dam. Passage is critical to the long-term genetic health of the population. Fish passage planning at Clear Creek Dam is complete and construction of a new fish ladder and cool water intake pipe will occur from 2025 - 2027. Planning for two-way fish passage at Tieton Dam is underway with completion of designs expected by 2027. A creel survey to quantify impacts of incidental catch and illegal harvest should be implemented in Rimrock and Clear Lakes and outreach and education to anglers should continue to be a priority. Solutions involving management or eradication of brook trout should be discussed as more evidence of introgression has emerged. Prey base in FMO habitat should be assessed and managers should consider implementing carcass analog placement to address lack of marine derived nutrients, if necessary.

Monitoring Needs/Key Questions

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Exploratory surveys upstream of barrier falls, eDNA?

Habitat assessment in Clear Creek

Brook trout introgression & suppression strategies

Monitoring of river channel through reservoir bed during low pool to assess dewatering, passage issues, OHV use, and other challenges.

Actions

Future link/ iframe to PowerApp will go in this section.

Completed Bull Trout Recovery Actions

• Fish ladders were installed in the spillway channel in 1992, but do not function as anticipated.

• Fishing regulations were implemented to protect bull trout in North Fork Tieton River.

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 annual spawning surveys to monitor trends in population abundance. (add PIT array and efishing effort USFWS 2024)
• Multiple Populations #3: Continue temperature monitoring
• Multiple Populations #5: Carcass analog placement if pilot studies demonstrate success
• Multiple Populations #7: Current genetic samples indicate that this population may have a high level of introgression with brook trout. Continue to monitor, targeting fish that show phenotypic hybrid characteristics.
• Multiple Populations #8: Manage Tieton Dam operations to reduce entrainment.
• Multiple Populations #9: Periodic entrainment studies at storage dams.
• Rimrock FMO Action #1: Provide connectivity at Tieton Dam
• Rimrock FMO Action #2: Reduce entrainment of bull trout through Tieton Dam
• Rimrock FMO Action #3: Manage reservoir pool levels to promote connectivity at tributary confluences (New Action in 2025)
• Rimrock FMO Action #4: Evaluate and manage ecological dynamics in Rimrock Reservoir (New Action in 2025)

North Fork Tieton River Actions

• North Fork Tieton Action #1: Provide bull trout passage at Clear Creek Dam
• North Fork Tieton Action #2: Environmental DNA sampling in tributaries
• North Fork Tieton Action #3: Evaluate options to address brook trout
• North Fork Tieton Action #4: Habitat work in Clear Creek (New Action in 2025)
• North Fork Tieton Action #5: Determine impacts of dewatering in the NF Tieton River and discuss mitigation options (New Action in 2025)

Actions in the Yakima Steelhead Recovery Plan that benefit this population

Areas upstream of Tieton Dam were not addressed in the Steelhead Recovery Plan.

Update Notes

2012 BTAP text copied into Yakipedia and edited to match new format in October 2024 by Aimee Taylor. ADD LINK TO 2012 BTAP pdf placemark

Additional edits proposed by Alex Conley, Aimee Taylor and Rimrock populations small group. Reviewed, and updated and approved by BTWG in February 2025.

Specific detail on out of cycle updates: