Upper Kachess River Bull Trout Population

Overview

The upper Kachess River is the smaller of two streams in what is locally known as the Kachess River/Mineral Creek system. Mineral Creek joins the river approximately 1.2 miles above the reservoir (at full pool) and contributes about 75% of the downstream flow (Meyer 2002). Despite this flow discrepancy the stream is referred to as the Kachess River below this confluence, a fact that has caused some confusion in the past. It is referred to as the upper Kachess River in this document to differentiate it from the lower Kachess River, a 0.6-mile reach below Kachess Dam that flows into Easton Reservoir and the Yakima River.

Mineral Creek originates in the Alpine Lakes Wilderness Area and the headwaters of the upper Kachess River originate on other lands managed by the Forest Service. The river flows into the north end of Kachess Reservoir. All accessible fish habitat in the two streams is in the Okanogan-Wenatchee National Forest. The upper Kachess River almost always goes dry for about 1.5-miles above the reservoir during late summer and early fall. Typically, the river also experiences intermittent subsurface flows further upstream in dry years.

Population Information

Population Distribution and Life History

Figure 1. PIT antenna detections of bull trout near the mouth of the upper Kachess River (denoted as "Lower Kachess River") in the figure title. Note the lack of water temperature data between mid July and late October, indicating the period where the river was dry. As water returned, bull trout were detected on the antenna in October and November.

The upper Kachess River population displays an adfluvial life history. The population spawns primarily in the upper Kachess River above the Mineral Creek confluence although a few redds are sometimes found downstream. While Mineral Creek contains some suitable spawning habitat, few redds are observed there. Juvenile bull trout are known to use both Mineral Creek and the upper Kachess River for rearing with their distribution extending down to the reservoir. Kachess Reservoir provides FMO habitat for subadult and adult fish. Unlike other populations in the Yakima River Basin which mostly migrate into the spawning tributaries between May and September, adults from this population have been observed to migrate into the upper Kachess River in October and November, after fall rains have re-watered the reach above the reservoir (W. Meyer, WDFW, pers comm, 2012) (Figure 1. Beebe et al. 2025).

Natural Barriers limiting distribution

Figure 2. The upstream passage barrier on the upper Kachess River, a ~60 foot waterfall.

Barrier waterfalls, which prohibit further upstream fish migration are located 0.6 miles up Mineral Creek (47.420986, -121.243165) and 0.9? miles up the upper Kachess River (47.423727, -121.234839) (Figure 2).

Population Genetics

Results of genetic analyses show this population is genetically distinct from all other populations in the Yakima Basin (Reiss 2003; Small et al. 2009). Baseline genetic samples were collected from juveniles during a snorkel survey conducted in 1997 by CWU researchers and WDFW biologists (Reiss 2003). A couple of adult bull trout were collected at the mouth of Box Canyon Creek in 2020. Rapid genetic analysis on these two bull trout showed the probabilities of the population of origin were 0.90 Box 0.10 Kachess and 0.53 Box and 0.47 Kachess, indicating some genetic introgression between the two populations (Von Bargen 2021).

Connectivity, and thus the potential for genetic exchange, with downstream populations in the Yakima River fluvial system, was eliminated by the construction of Kachess Dam in 1912. For more detailed information, see the Population Genetics section of the Kachess Reservoir Bull Trout Population Group page.

Population Monitoring

Four adult bull trout were observed in October 1980 in the upper Kachess River by a WDFW (then Washington Department of Wildlife) electrofishing crew (USFS 1980). Brown (1992) also reported that adults were found in Mineral Creek and that bull trout redds (three in Mineral Creek and two in the Kachess River) were observed. Returning in 1993 on four separate dates between late August and mid-October, no adult bull trout were found, though juveniles were. A CWU graduate student reported the presence of “small” adult bull trout in the Kachess/Mineral system in July 1996, but found no redds when he returned in October (Craig 1996). In 1998, WDFW conducted an exploratory redd survey, but found no redds or adult bull trout. It was not until two years later that adult presence was once again documented, when 17 adults were observed in 11 snorkel surveys conducted from July thru November 2000 (Meyer 2002; James 2002a). 15 bull trout redds were found in the first complete redd survey conducted that same year. Through these efforts, it became clear that the timing of adult bull trout presence in the upper Kachess River was dependent on fall precipitation, which reconnected the river with the lake and that the population was adfluvial. Ongoing redd surveys conducted since 2000 support this (Divens 2025).

Juvenile bull trout presence in the Kachess/Mineral system was first documented in 1980 when WDFW conducted the electrofishing described above; bull trout were found in both streams. The Forest Service observed juveniles in snorkel surveys conducted in Mineral Creek in 1990 and 1991. Craig (1996) observed juvenile bull trout in the system in 1996. CWU researchers Paul and Brenda James, with assistance from WDFW, snorkeled about 0.7 mile in the Kachess/Mineral system in 1997 starting about a tenth of a mile below the confluence of the two streams and continuing up Mineral Creek to the barrier waterfall and obtained genetic samples from 30 juvenile bull trout (Reiss 2003). In 2000, CWU graduate student William Meyer conducted snorkel surveys from late July through mid-November from the mouth of the upper Kachess River up to the barrier waterfall on the river and observed both juvenile and adult bull trout. For his thesis work investigating the effects of seasonal dewatering on different age classes of bull trout, he calculated juvenile densities, determined adult migration and spawn timing, monitored stream discharge and channel condition, and documented life-stage specific mortalities resulting from channel dewatering (Meyer 2002).

In 2019, the Yakama Nation initiated their Bull Trout Population Restoration and Monitoring Project with the goal of maintaining and increasing population numbers and monitoring population trends. As part of this project, young of year (YOY) bull trout are rescued from the dewatering reach of the upper Kachess River and temporarily relocated to La Salle fish rearing facility, where they are fed a natural diet. As of 2024 1,303 upper Kachess River YOY have been reared in captivity, tagged, and released into the reservoir about 10 months later. In 2024, the first of those bull trout were detected entering the river during the spawning season. In 2025 more detections occurred and video evidence of bull trout staging to spawn was captured, indicating that rescued YOY were successfully reared in captivity and survived to spawn and contribute to the next generation.

Yakama Nation and USFWS maintain PIT antennas at two locations in the upper Kachess River, a lower site, 0.2 km upstream of the mouth and an upper site, 1 km upstream of the mouth. The lower array has been frequently blown out and vandalized and has consisted of permanent pass through types and temporary submersible types (sometimes a combination) over the years. They also maintain antennas in lower Box Canyon Creek (0.2 km upstream from the mouth) and temporary antennas in the Box Canyon Creek Flume when it is constructed and in The Narrows during low water.

PIT-tagged Kachess River fish come from four sources: 1) juveniles collected in the upper Kachess River, reared over the winter at La Salle, and then released into Kachess Reservoir, 2) juveniles collected in the upper Kachess River, tagged, and immediately released, 3) adults collected during trap and haul below Kachess and Keechelus dams, and 4), adults collected and tagged in Box Canyon Creek during various collection attempts at Peekaboo Falls and the Box Canyon Creek Flume from 2019 - 2021.

Detection of PIT-tagged fish in the upper Kachess River is challenging for a few reasons. First, the lower river can be dry for much of the summer and fall (mid July - late October in 2024). Second, the antennas are powered by batteries charged by solar panels and by the time fish enter the river, sunlight has waned and snowfall can limit both the solar panels' ability to charge the batteries and access to the site. The lack of detections and ultimately the initial evaluation of the La Salle program has probably been influenced by compromised antenna operations and resulting lack of detections. In contrast the lower Box Canyon Creek sites are powered by propane. In 2023, 13 Bull Trout were detected in the upper Kachess River, most of which had been collected and immediately released back into the upper Kachess River, although a single La Salle fish was detected at the lower site. However in 2024, eleven unique Bull Trout were detected in the upper Kachess River from October 28 - November 22, all of which were La Salle fish released from 2020-2022. Eight fish were detected at the lower site and three fish were detected at the upper site but no fish were detected at both sites. (Beebe et al. 2025 a,b). See the Box Canyon Creek population monitoring section for Kachess River fish detected in Box Canyon Creek.

The USFWS also conducted a two-year acoustic telemetry study of Bull Trout spatiotemporal movements in Kachess Reservoir which opportunistically included a drought (2022) and non-drought year (2023). The study found that although The Narrows becomes a complete fish passage barrier when Kachess Reservoir water surface elevation drops below 2205 ft., it can also become a thermal barrier beforehand that restricts fish to Big Kachess and limits access to spawning tributaries in Little Kachess. The study found that during 2022, fish moved across The Narrows in both directions, but in 2023, most fish moved south of The Narrows by mid-summer and no crossings occurred after July. Fish used in the study were 36 juvenile Bull Trout rescued from the upper Kachess River and reared at La Salle over the winter (Hamilton et al., 2025).

-WDFW: demographic surveys

Redd Surveys

Figure 3: Upper Kachess River bull trout redd counts from 1998-2025

There has been an attempt to conduct complete redd surveys in the river since 2000. These surveys cover the entire upper Kachess River from Kachess Reservoir (which is at low pool at that time) to the barrier waterfall, a distance of approximately 2.5 miles. The annual count has been highly variable (Figure 3).The spawning period for this population depends entirely on fall precipitation which rewaters the stream channel and allows access to the spawning grounds. In a typical year, this period extends from mid-October thru mid-November, at least a full month later than for other bull trout populations in the Yakima Basin. While the rains provide necessary access for fish, they also can hamper the ability to monitor this population. The upper Kachess River responds quickly to rainfall, and high flows have often severely reduced or eliminated the ability to conduct complete redd surveys. High flows commonly result in incomplete surveys and obscured redds between passes.

Up until 2019, Mineral Creek was only occasionally surveyed.  Starting in 2020, Mineral Creek has been surveyed every year, though not necessarily with the three recommended passes. Brown (1992) reported that three redds were found in the creek in 1980. Between 1980 and the publication of the 2012 Bull Trout Action Plan, no adults or redds had been observed there. However, surveys at the time were only spot checks. More recently, the reach accessible to bull trout in Mineral Creek has been established as a yearly spawning survey index (1 pass per year starting in 2020, 3 passes per year starting in 2023). Several adult bull trout and a small number of redds have been observed since.

Other Distribution Data (eDNA, etc.)

One eDNA sample was collected in the upper Kachess River above the barrier waterfall in 2017 (Parrish 2017). The result was negative for bull trout DNA. Likewise, three samples were collected above the Mineral Creek barrier waterfall at 1km intervals and the results were negative for bull trout DNA.

Population Status and Trend

The USFWS (1998) considered the Kachess River subpopulation to be depressed, decreasing, and at risk of stochastic extirpation. At the time this subpopulation did not include the upper Kachess River local population as bull trout spawning had not been observed yet in the upper Kachess River and a local population was not recognized. WDFW rates the status of the Kachess Reservoir stock (which included the upper Kachess River population) as critical, further stating that it was very near extirpation (WDFW 2004).

While redd counts are somewhat incomplete due to environmental conditions during the spawning survey season, the 26 years of data show a variable population trend. Nonetheless, the population is small. Despite the upper Kachess River population’s obvious obstacles (i.e., access and limited habitat area), it continues to persist. The highest redd count on record (33) was documented in 2011.

Habitat

Habitat Overview

Elevations on the upper Kachess River range from 2,270 feet at its mouth to about 2,500 feet at the barrier waterfall, which is similar to the elevation at the base of the barrier falls on Mineral Creek. All of the reaches accessible to bull trout in both streams are located in the Okanogan-Wenatchee National Forest. The upper Kachess River has a varied history of resource extraction (Meyer 2002). Copper deposits were discovered on Mineral Creek in the late 1800s. A wagon road was built shortly thereafter to extract ore mined from the hillsides adjacent to the creek. The tailings of the mining operation are still visible as are the remains of the mining operations, even though they ended long ago. The watershed was heavily logged from 1968 through 1987 with some harvest occurring directly adjacent to the lower segment of the upper Kachess River. The roads that were built to accommodate timber harvest have been decommissioned except for FS 4600, which is the main road used to access the Mineral Creek Trailhead. The end of the road was decommissioned in 2025 where it entered the Kachess River floodplain. The road interrupted flow across the floodplain and probably contributed sediment to the stream. With the decommissioning of this portion of road, the Mineral Creek Trailhead was relocated. Human activity in the watershed is limited to recreation, including hiking and canyoneering, which has become a popular sport in Mineral Creek in the past decade.

Habitat conditions in the upper Kachess system vary (except for water temperatures which are suitable throughout). Above the confluence of Mineral Creek and the Kachess River, the stream gradient of both streams is between 2 and 7% with channel widths ranging between 15 and 25 feet. Pools are frequent, LWD is prevalent and the availability of spawning-size gravels, at least in the upper Kachess River, is good. The riparian corridor on both streams is composed of typical old-growth understory species and is healthy. Below the confluence for a distance of about 0.5 mile, high alluvial banks frequently confine the river. The channel widens, stream gradient decreases to about 1%, and pool frequency and depth decreases. The riparian corridor shows some signs of past disturbance but can still be described as healthy. Below this reach habitat conditions change dramatically. The channel width often exceeds 150 feet; LWD is scarce. The segment contains mostly riffle habitat and few pools. It is within this reach, often beginning near its downstream end, that the upper Kachess River goes completely dry almost every year in the late summer and early fall. There may be short intermittent sections of flowing water, but for the most part the water in the river goes subsurface. These conditions are believed to result from the deposition of massive amounts of alluvial material, most likely tailings left from past copper mining activities, which washed down during flood events (Meyer 2002). The river generally remains disconnected until fall rains reconnect it, typically sometime in October.

FMO habitat for the upper Kachess River bull trout population is in Kachess Reservoir. Neither the sparse shoreline development or water sports activities on the lake are believed to influence habitat quality. The effects of reservoir depletion during the summer and early fall are less concerning in Kachess Reservoir than in any of the other Yakima basin impoundments. The reservoir has a conservation pool (i.e., inactive storage) of 585,000 acre-feet that cannot be accessed for irrigation withdrawal. However, in drought years when the reservoir is drafted to its lowest level, the Kachess Narrows may inhibit or discourage passage between Big and Little Kachess due to the elevated water temperatures and lack of habitat cover (Taylor 2022). Under a KDRPP (Kachess Drought Relief Pumping Plant) scenario, the Kachess Narrows could completely block upstream passage for up to five years depending on weather conditions. Under this condition, some bull trout would not be able to access their spawning grounds since those are accessed from the Little Kachess basin. Even under current operations, back to back drought years can limit reservoir refill and create thermal barriers at the Kachess Narrows (Hamilton et al. 2025).

Habitat Monitoring

Field Habitat Surveys

Figure 4. Periods of dewatering in the upper Kachess River over three years, extrapolated from temperature monitoring near the mouth of the Kachess River (winter dewatering periods are more difficult to detect given similar air, water and snow temperatures).

Meyer (2002) studied the effects of dewatering on juvenile bull trout and adult migration. The lower reach of the upper Kachess River is generally dewatered from mid-summer (average date of disconnections is 7/17 with a range between 6/30 and 8/2) until heavy precipitation waters the channel in late fall (Scott Kline, WDFW, personal communication). Dewatering conditions have been noted during annual redd surveys since 2000. In 2017 WDFW fish passage biologists started annual monitoring of the timing and extent of dewatering via weekly surveys. A water temperature logger near the mouth of the creek also provides insight on yearly dewatering trends (Figure 4).

Mongillo (1982) measured water quality parameters and zooplankton densities in Kachess Reservoir. There has been limited Forest Service monitoring in this reach of the Kachess River. Hansen et al 2017 studied the food web of Kachess Reservoir and found that its late-season drawdown allows for a more robust food web than Keechelus Reservoir, but could be negatively impacted if the current kokanee fry stocking was discontinued or the drawdown shifted to earlier in the season.

WDFW assisted with installation of temperature monitoring equipment in the Kachess River at the Mineral Creek trail crossing in 2015 and in Mineral Creek just above the confluence with the Kachess River beginning in 2018.  WDFW has been taking flow measurements at those sites since 2018. WDFW also installed a temperature probe between 2019 and 2020 in the inundation zone and starting in 2020 in the Kachess River about ½  a mile above the Mineral Creek confluence.  Occasional flow measurements have been taken in the Kachess River near the high pool extent to document dewatering in that area and in the Kachess River just above the Mineral Creek confluence since 2018. Flow measurements are to understand the flow balance between Mineral Creek and the upper Kachess River and flow loss across downstream reaches.

WDFW completed a modified Hankin and Reeves type of habitat survey in the perennial flow of the upper Kachess River and Mineral Creek in 2016, and in the dewatering section of the Kachess River in 2017.  Wood quantification for these areas was completed by the USFWS in 2017. Ground water monitoring....

WDFW completed macroinvertebrate collections at 10 locations with three replicates each over two days in mid-September 2016 in the upper Kachess mainstem, Mineral Creek, and the Kachess River above the confluence with Mineral Creek. Macroinvertebrates were identified to order level.  Though further work was intended, no additional samples were taken and no more detailed identification of samples occurred.

Stream Temperature Data

WDFW and USFWS have monitored water temperature in the upper Kachess River. Water temperature monitored at PIT antenna sites ranges to a maximum of about 14°C. ADD SOME GRAPHS

Is there a logger at the upper antenna site? WHO OPERATES??

Restoration Actions

Since 2016, Kittitas Conservation Trust, along with partners, have been working to develop and implement plans for restoration actions to restore Kachess River and its floodplain.  In 2023 restoration of phase one was completed, installing 1,576 logs and whole trees in 65 structures throughout the 1.2 miles of Kachess River downstream of the confluence with Mineral Creek.  Logs were primarily harvested through targeted forest health treatments on site.  13,964 live plants were installed to provide future riparian vitality and habitat for aquatic and terrestrial species.  The primary goal of this work was to create deeper pools with cover that is connected to ground water to aid in juvenile survival during annual dewatering periods.  In 2025, phase 2 was completed with an effort to remove existing trailhead and road from the floodplain and replace it with a new trailhead and trail up out of the floodplain.  The goal of this work was to improve water quality and restore tributary flows across the floodplain to help with water storage on the eastern floodplain through wetland retention and shallow water aquifer storage.

Threats

Connectivity

Fish Passage Barriers

Threat Severity: Significant

About a mile of the Upper Kachess River dewaters annually. The dewatering typically begins at confluence with the reservoir and extends upstream, with flows going fully subsurface in late July to mid-August. This is believed to occur due to past land use activities including mining and logging (Meyer 2002). These activities increased channel width, reduced LWD recruitment, and resulted in massive amounts of alluvial material settling in the valley bottom. See Habitat Overview section above. During the Kachess River Restoration Project implemented by Kittitas Conservation Trust in 2023, it was also discovered that the geology plays a role in the sub-surface flows in the ~0.75 mile of stream closest to the reservoir. This area was likely to dewater historically. The river generally remains disconnected from its upstream reaches until fall rains reconnect it, typically sometime in October. The Kachess River bull trout population spawns upstream of the dewatering area.

Sometimes large and small woody debris create temporary passage barriers in the upper Kachess River, upstream of the confluence with Mineral Creek. In 2023, chainsaws and hand tools were used to modify a debris jam to allow passage to the spawning grounds.

Kachess Dam is also a fish passage barrier. Although this population is thought to have always had an adfluvial life history strategy, historically these fish had connectivity with the rest of the Yakima River system and may have migrated long distances. Likewise, bull trout from other Yakima River populations would have been able to access the spawning grounds in the Upper Kachess River. The construction of Kachess Dam in 1912 inhibited upstream movement of bull trout and genetically isolated the current population.

Entrainment

Threat Severity: Unknown, likely significant

Between 2019 and 2024, 2,402 bull trout have been rescued from dewatering in the Upper Kachess river and raised in captivity by Yakama Nation. 1,303 of those were tagged and released into Kachess Reservoir. Only four of the tagged fish have been documented getting entrained through Kachess Dam since tagging began. While there is not a PIT antenna collecting information on tagged fish directly below Kachess Dam, some of the Kachess bull trout have been captured by USFWS below Kachess and Keechelus dams.

Dewatering due to flow management

Threat Severity: Unknown, likely significant

When high-energy flows carrying bed load hit the standing water at the edge of the reservoir, there are large deposition events that increase the elevation near the mouth of the creek, and may exacerbate fish passage issues under low flow conditions. When the reservoir is at low pool, dewatering extends across the reservoir bed. Despite the river going dry in this section, reservoir management is not the primary factor causing dewatering. However, the section of river flowing through the reservoir bed tends to reconnect to the reservoir sooner than upstream reaches and spawning has been known to occur here when bull trout cannot access the upper river. Spawning is not successful when eggs are laid in the inundation zone due egg smothering when the reservoir pool level increases. Between 2009 (when individual redds started getting GPS locations) and 2024, about 12% of the redds have been built in the reservoir inundation zone. This amount of lost reproductive effort may have substantial negative impacts on the population.

Land-use Issues

Forestry

Threat Severity: Insignificant (historical effects still significant).

The Kachess Reservoir watershed experienced substantial timber harvest in the mid 1900s, with commercial logging at the Kachess River occurring primarily between 1968-1986 (Meyer 2002). Logging on USFS lands went along the river corridor all the way to the banks of the creek. Approximately half the riparian area was logged. Roads were built to haul materials and logs out of the site. Plum Creek Timber company owned land nearby, and also clear cut large swaths of land in the watershed (Meyer 2002). The effects of clear cut logging and associated roads include reduced stream sinuosity and reduced recruitment and storage of large woody debris. Both of these factors, in addition to mining effects, contribute to bank instability, excessive cobble deposition in the valley bottom, and annual dewatering.

Agriculture and Grazing

Threat Severity: Insignificant

There is no current agriculture or grazing in this area.

Recreation

Threat Severity: Unknown, likely insignificant

The Kachess River population of bull trout utilize Kachess Reservoir and the Upper Kachess River. The majority of recreational impacts probably occur on the west side of the reservoir in and around Kachess Campground. The campground has ~100 developed campsites and stays busy throughout the summer season. There is a motorized and a non-motorized boat launch, so water activities are popular including fishing, boating, kayaking, stand up paddle boarding and swimming. The Mineral Creek Trailhead is a popular site for backpackers to access Alpine Lakes Wilderness. The former parking area was located adjacent to Kachess River and a small intermittent tributary, which increased sedimentation and road maintenance needs in the direct vicinity of Kachess River. Hikers also have to cross the river to continue on the trail, and often place wood or rocks across the creek as a "bridge." The impacts to bull trout from these recreational activities have not been quantified. In 2025, as the final part of the Kachess River Restoration Project, the Mineral Creek Trailhead and parking area were relocated away from the creek, and the old road and parking area were decommissioned.

A newer activity in the watershed is canyoneering (first descent noted as 2020 via Rope Wiki), particularly occurring in Mineral Creek. The canyoners are known to take the trail adjacent to the creek until they reach their desired access points, at which point they descend to the creek. This may not have direct impacts to bull trout habitat, but there is potential for downstream flow of waste, etc.

Roads and Development

Threat Severity: Insignificant (historical effects still significant)

There are approximately 5 miles of road along the West shore of Kachess Reservoir to allow access to housing developments and the campground. This road is not thought to have negative population effects. Housing and the campground are probably not impacting bull trout negatively. The sedimentation and issues with the road leading to the old Mineral Creek Trail should be mitigated through the 2025 decommission and trailhead relocation project.

Historic road building in the floodplain of the upper Kachess River probably had the largest impact on this population through alteration of spawning and rearing habitat. During the Kachess River Restoration Project, some of these old road beds were utilized for access, then returned to a "natural" condition. They have now been officially decommissioned, by USFS definition.

Mining

Threat Severity: Insignificant (historical effects still significant)

Copper mining occurred in the headwaters of Kachess River and Mineral Creek in the early 1900s. The mine tailings were sluiced downstream into Mineral Creek and with decades of high-energy stream flow there has been an excessive amount of rough cobble material deposited into the floodplain down below (Meyer 2002). Deposition of gravels and cobbles has likely worsened dewatering conditions in the lower 1.5 miles of stream habitat.

Ecological Interactions

Brook Trout

Threat Severity: Unknown, likely insignificant

Only six brook trout have been observed in the upper Kachess River over nine years of demographic surveys. Hybridization has not been documented here. Brook trout have been observed in Kachess Reservoir and Box Canyon Creek and may be abundant in some of the reservoir tributaries, including Lodge Creek. The distribution in the watershed is not fully understood, but there are some surveys that help elucidate distribution (See Kachess Reservoir FMO Habitat for more details). When brook trout are observed during demographic surveys in Box Canyon Creek, snorkelers attempt to capture and cull the fish. Kachess Reservoir tributaries may be a good candidate for brook trout suppression and/or eradication because they have not fully established in bull trout spawning and rearing tributaries.

Other Invasive Species

Threat Severity: Insignificant

There have been no reports of other invasive species in the upper Kachess River.

Diminished Prey Base

Threat Severity: Insignificant

A 2017 study in Kachess Reservoir found that feeding rates of bull trout are not limited by foraging opportunities and that the prey base in the reservoir could support larger populations of bull trout (Hansen et al. 2017). The authors noted that annual stockings of kokanee are an important source of prey for bull trout in Kachess and should continue. These stocked kokanee probably make up for the lack of anadromous smolt production after the construction of Kachess Dam.

Extensive drawdown of Kachess Reservoir, such as under a KDRPP scenario, would reduce littoral prey production and lead to food-web compression (Hansen et al. 2017), potentially resulting in reduced foraging efficiency and shifts in bull trout habitat use and prey selection (Taylor 2022).

The study did not look at prey base in the Upper Kachess River. Juvenile bull trout primarily feed on macroinvertebrates. Density and concentration of macroinvertebrates may be affected by dewatering and low flow conditions.

Disease

Threat Severity: Insignificant

No instances of disease have been reported.

Water Quantity and Quality

Flow issues/dewatering

Threat Severity: Significant

The upper Kachess River goes completely dry almost every year in the late summer and early fall in the 1.5 miles above the reservoir. There may be short intermittent sections of flowing water, but for the most part the water in the river goes subsurface. These conditions are believed to result from the deposition of massive amounts of alluvial material, most likely tailings left from past copper mining activities, which washed down during flood events (Meyer 2002). The river generally remains disconnected from its upstream reaches until fall rains reconnect it, typically sometime in October. Juvenile bull trout become stranded in isolated pools. Some are rescued and relocated to perennial flow, or given to the Yakama Nation for captive rearing. Those fish that evade rescue eventually desiccate.

Current and modeled future temperature conditions

Threat Severity:

Other changes in hydrology

Threat Severity: Significant

Instances of drought have increased over the past few decades and contribute to reduced snowpack, earlier peak run-off and extended periods of dry streambeds. Lack of summer and fall rains, combined with geomorphology, inhibit fish passage into the Upper Kachess River, potentially impacting reproductive success of adult bull trout.

Fisheries Impacts

Angling Regulations/Fisheries Use/Poaching (Recreational)

Threat Severity: Unknown, likely significant

The upper Kachess River is closed to fishing year-round to protect bull trout. The remote nature of the creek makes access somewhat difficult, so fishing pressure is probably reduced.

Fishing is common in Kachess Reservoir, but the target species is primarily kokanee. A WDFW creel survey at Kachess Reservoir in 2022 observed no harvested bull trout throughout the busy summer season (Divens 2026). However, three bull trout were reported caught and released by anglers, which equated to an estimated 28 in total. An additional 11 fish were reported caught, unidentified and released, some of which were possibly bull trout. It is likely that some portion of the bull trout caught and released by anglers succumbed to hooking mortality. Low reservoir population numbers may limit the number of bull trout encountered by anglers. Angler education on bull trout identification and angling regulations seems to help reduce the number of bull trout lost to recreational angling (Divens 2026). While the exact impact of fishing/poaching is unknown, it is not zero. With the population trend for Kachess River bull trout, any level of catch or harassment could have significant negative impacts.

Management/Monitoring (Research)

Threat Severity: Unknown

The Kachess population of bull trout is one of the most highly studied in the Yakima River Basin. Research impacts on the population are unknown and unquantified. Annual redd surveys involve hiking in the stream. Bull trout are observed passively in snorkel surveys, actively rescued from dewatering, and handled for biological sampling of fin tissue and measurements. All captured bull trout >100 mm are PIT tagged. A study from 2019-2021 surgically inserted acoustic tags into wild-captured and captive-reared bull trout. Bull Trout from the Kachess River population are being reared in captivity and released at a larger size. While the program has had overall success in survival, there has been mortality of Kachess River bull trout in captivity. Another concern are the genetic implications of the fish rescue program.

Other Threats

Low population abundance, inbreeding

Climate Change

Summary of Primary Limiting Factors and Threats

The highest severity threats to this population are passage barriers (dewatering and Kachess Dam) and low population abundance. Dewatering in the lower reaches of the spawning tributary also appears to be limiting the population through stranding of juvenile and YOY bull trout and access to the spawning grounds. This potentially natural effect is exacerbated by reservoir fluctuations, legacy logging and mining impacts, and climate change. These factors work to increase the seasonal period of dewatering and limit habitat. Restoration of the lower portion of the river should mitigate some of these effects. Other threats include angling in Kachess Reservoir, entrainment at Kachess Dam, lack of marine derived nutrients, potential expansion of brook trout, and the limited habitat due to the inundation of lower reaches of the upper Kachess River when the dam was completed and the reservoir filled. An emerging threat is the potential of inbreeding and inbreeding depression due to small population size.

While forest management and recreation issues are present, they are not considered a significant threat. Threats due to agriculture, development, grazing, transportation issues, and mining are not present in this population area.

Recovery Strategy

Population-level Recovery Strategy

This population has been identified as a “Protection” population with a priority for continuation of population monitoring, but with limited restoration actions recommended. <-UPDATE? A LOT OF WORK GOING ON HERE

The highest priority actions involve passage at the broad scale (Kachess Dam) and addressing low abundance via rescue-and-rear of stranded bull trout. Ongoing monitoring and adaptive management strategies for rescued bull trout needs to be ongoing to reduce the potential of negative genetic effects to the population. Other recommended actions are outreach to educate anglers and recreationists and carcass analog placement if pilot study results from Box Canyon Creek are positive. The Kachess River Restoration Project (see Restoration Actions above) was initially discussed in 2016 and was implemented in 2023 to reduce the threat of dewatering and improve habitat.

Monitoring Needs/Key Questions

---

Continuation of post-restoration project monitoring: habitat and fish demographics

Genetic monitoring

Ongoing temperature monitoring

Actions

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

Completed Bull Trout Recovery Actions

Kachess Action #1:

• Step 1 - Hydrogeomorphic evaluation in upper Kachess River (not Mineral Creek) to determine mechanisms and solutions for annual dewatering (completed prior to implementation).
• Step 2 - Implementation of a habitat enhancement project (completed in 2023).

Kachess Action #2:

• Step 1 - Mineral Creek Trailhead restoration (relocation of trailhead and restoration of old parking area was completed in 2025).

Recommended Actions

Relevant Multiple Population Actions

Multiple Populations #1: Provide outreach on bull trout conservation issues (landowners, recreationists, anglers, school groups, and others).

Multiple Populations #2: Continue redd surveys within established index areas to monitor long-term trends in abundance.

Multiple Populations #3: Continue temperature monitoring

Multiple Populations #4: Conduct supplementation feasibility

Multiple Populations #7: Monitor any genetic samples for introgression with brook trout.

Multiple Populations #9: Periodic entrainments surveys at storage dams

Kachess River Actions

Kachess River Action #1: Upper Kachess River Habitat and Passage Projects

Kachess River Action #2: USFS Road and Recreation Area Management

Kachess River Actions #3: Supplementation, Fish Salvage and/or Translocation

Actions in the Yakima Steelhead Recovery Plan that benefit this population

None

Update Notes

2012 BTAP text copied into Yakipedia and edited to match new format in October 2025 by Aimee Taylor. ADD LINK TO 2012 BTAP pdf placemark

Additional edits proposed by Alex Conley, Aimee Taylor and Kachess River/Box Canyon Creek small group. Reviewed, and updated and approved by BTWG in XXXXXXXXXXXXX

Specific detail on out of cycle updates: