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/Mineral system. Mineral Creek joins the river approximately 1.2 miles above the reservoir (at full pool) and contributes an estimated 75% of the combined flow of the two streams (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 short reach remaining below Kachess Dam before it flows into Lake Easton 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 Kachess Lake at its northern end. Barrier waterfalls, which prohibit further upstream fish migration on Mineral Creek and the upper Kachess River, are located about 0.6 and 0.9 miles upstream of the confluence of the two streams, respectively. All accessible fish habitat in the two streams is in the Okanogan-Wenatchee National Forest. The upper Kachess River almost always goes dry for a considerable distance above the lake during late summer and early fall. Typically the river also experiences intermittent subsurface flows even further upstream in dry years (up to about a mile).

Population Information

Population Distribution and Life History

The upper Kachess River population displays an adfluvial life history type. It is possible that a resident component exists as well although this has not been confirmed. The population spawns primarily in the upper Kachess River above the Mineral Creek confluence although a few redds are sometimes found below this point. While Mineral Creek contains some suitable spawning habitat bull trout do not appear to spawn there. Brown (1992) reported that three redds were found in the creek in 1980 but no bull trout redds or adult bull trout have been observed since. However, the surveys done in Mineral Creek are mostly spot checks and not part of the established index area so it is possible that some undetected spawning activity takes place. Juvenile bull trout are known to use both Mineral Creek and the upper Kachess River for rearing with their distribution extending to the lake. Kachess Lake provides FMO habitat for subadult and adult fish (Figure 21). Adults have been observed to migrate into the upper Kachess River in October, after fall rains have re-watered the reach above the lake (W. Meyer, WDFW, pers comm, 2012).

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). Genetic samples for the baseline were collected from juveniles during a snorkel survey conducted in 1997 by CWU researchers assisted by WDFW biologists (Reiss 2003). 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.

Population Monitoring

The documentation of bull trout in Kachess Lake was described above in the Box Canyon Creek population section. Adult bull trout (four) were first observed in October 1980 in the upper Kachess River by a WDFW (then Washington Department of Wildlife) electrofishing crew (USFS 1980). Brown 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 finding no redds and observing no 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). That same year 15 bull trout redds were found in the first complete redd survey conducted. Through these efforts, it became clear that the timing of adult bull trout presence in the upper Kachess River was dependent on fall precipitation reconnecting the river with the lake and that the population was thus adfluvial. The redd surveys conducted since 2000 support this.

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 observed juvenile bull trout in the system in 1996 (Craig 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. They 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. He 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 2011, the USBR conducted an entrainment study directly below Kachess Dam. A screw trap and a fyke net were deployed in the river channel to capture fish entrained through the outlet works of the dam and passed to the river below. The sampling was done over a range of flow releases from mid-June through mid-October. Nearly 2,700 fish were captured during the course of the study representing 16 species, but no bull trout were collected (Arden Thomas, USBR, pers comm).

Redd Surveys

The spawning period for this population totally depends on fall precipitation rewatering the stream channel and allowing access to the stream. 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. 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 Lake (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 20). High flows in three years (2005, 2006, and 2009) resulted in incomplete surveys and very low counts. In 2008, high flows between survey passes are suspected of obscuring redds established between surveys.

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 Lake stock (which included the upper Kachess River population) as critical, further stating that it was very near extirpation (WDFW 2004).

Environmental conditions during the spawning survey season are not conducive to determining a trend for this population. Nonetheless the population is clearly 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, a similar elevation as the base of the barrier falls on Mineral Creek. All of 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 does not impact the upper Kachess River and ends a short distance from the lower portion of it. Currently the main human activity in the watershed is recreation, which is limited to a hiking trail that crosses the lower river near where FS 4600 ends.

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 upstream 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 from its upstream reaches until fall rains reconnect it, typically sometime in October.

FMO habitat for the upper Kachess River bull trout population is in Kachess Lake. 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 Lake than in any of the other Yakima basin impoundments. The reservoir has a conservation pool (i.e., dead storage) of well over 400,000 acre-feet that cannot be accessed for irrigation withdrawal.

Habitat Monitoring

Field Habitat Surveys

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 until heavy precipitation waters the channel in late fall. Flows have been monitored during annual spawning surveys since 2000.

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. To date no habitat surveys, sediment monitoring efforts, road inventories, or even temperature monitoring have been conducted. This is identified as a monitoring gap.

Threats

Connectivity

Fish Passage Barriers

Threat Severity: Significant

About 1.5 miles 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.

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, significant??

Since 2019, XX bull trout have been rescued from dewatering in the Upper Kachess river and raised in captivity by Yakama Nation biologists. Bull trout are tagged and released into Kachess Lake. XX 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 Keechelus Dam.

Dewatering due to flow management

Threat Severity: Unknown, significant?

Discuss issues at Kachess Narrows, and lower portion of Upper Kachess River as it relates to water management

Land-use Issues

Forestry

Threat Severity: Insignificant (historical effects still significant).

The Kachess Lake watershed experienced significant 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.

Roads and Development

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Mining

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Ecological Interactions

Brook Trout

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Other Invasive Species

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Diminished Prey Base

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Disease

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Water Quantity and Quality

Flow issues/dewatering

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Current and modeled future temperature conditions

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Fisheries Impacts

Angling Regulations/Fisheries Use/Poaching (Recreational)

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Management/Monitoring (Research)

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Other Threats

Low Population Resiliency

Climate Change

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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 XXXXXXX small group. Reviewed, and updated and approved by BTWG in XXXXXXXXXXXXX

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