Seattle Public Utilities Mami Hara, General Manager/CEO

 

Bull Trout

 

Bull trout (Salvelinus confluentus) were listed as threatened under the Endangered Species Act in 1999. Within the Cedar River Municipal Watershed, bull trout are found in the Masonry Pool, Chester Morse Lake, and portions of several tributaries to the lake, including the Cedar and Rex rivers and Rack Creek. Although bull trout can be anadromous (born in fresh water but migrate to salt water), the CRMW population of bull trout is isolated by Cedar Falls, a natural barrier to upstream migration on the Cedar River. Most bull trout in the CRMW are adfluvial, residing most of their life in the lake environment, but spawning in streams. Read more about bull trout life history and ecology on the Seattle Public Utilities Cedar River Biodiversity website.

Historically, the bull trout population in the upper Cedar basin has faced, challenges from both natural (floods) and human activities (commercial logging) in the watershed. Road building and past timber harvest have affected stream conditions, degrading spawning and rearing habitat. Despite these adverse impacts, annual redd counts suggest that the bull trout population is currently relatively stable. Streams are now recovering from historical impacts, as the watershed is managed as an ecological reserve under the HCP with no commercial timber harvest. In addition, SPU is implementing a variety of restoration actions to restore natural ecosystem processes that should benefit bull trout.

Other potential impacts to bull trout stem from the operation of the Masonry Pool and Chester Morse Lake as a reservoir with fluctuating water levels. For example, raising the lake level to store water for the municipal water supply or flood control in the lower Cedar River in the winter and early spring can inundate bull trout redds, where eggs are developing. Inundation increases the potential for sedimentation of redds, which can cause egg mortality.

The necessity to lower the lake level to below the normal operating range in fall months could have negative impacts to bull trout. Very low lake levels during fall when bull trout are spawning could potentially affect access to spawning habitat, adversely impact spawning habitat in the Cedar and Rex rivers, and encourage fish to spawn lower in the system. Habitat conditions in these lower reaches may be of lower quality, and redds in these lower reaches will become inundated in the spring when lake levels typically rise.

Operation of a permanent pumping plant to move water from Chester Morse Lake downstream for supply and/or to protect anadromous fish habitat in the lower basin during times of especially low lake levels could affect bull trout in the lake by altering temperature regimes, food supplies, or other significant ecological processes.

SPU is undertaking a number of studies to better understand the ecology of bull trout in the CRMW and evaluate potential impacts from reservoir operations.

Goals

Adult bull trout

Adult bull trout in the Cedar River, photographed by Gilbert Arias, Seattle Post Intelligencer.

Our long term goal for bull trout is to maintain and/or improve existing habitat needed for each bull trout life stage, including spawning habitat, rearing habitat, and habitat conditions for adult fish in the reservoir system.
Our specific objectives include:

  1. Protect and maintain all aquatic and riparian habitats within the potential distribution of bull trout.
  2. Protect bull trout from human disturbance and fishing by maintaining a closed watershed.
  3. Restore stream and riparian habitat and more natural hydrologic processes throughout the upper basin.
  4. Reduce sediment delivery to streams by decommissioning roads to improve spawning and rearing conditions for bull trout.
  5. Provide scientifically sound information about bull trout ecology to better inform management decisions concerning reservoir operations.

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What are we doing?

Strategic Planning
The Cedar River above Chester Morse Lake is a focus for a variety of restoration projects aimed at restoring hydrologic processes, improving water quality, and improving stream habitat, all of which contribute to better rearing and spawning conditions for bull trout.
View more about our strategic planning.

Protect All Watershed Habitats
Management of the watershed serves to avoid and/or minimize adverse effects of major events and activities that could harm the bull trout population or its habitat, such as wildland fire, spills of toxic materials, invasive species, and excessive human disturbance.
View more information on habitat protection.

Aquatic and Riparian Habitat Restoration
Aquatic restoration projects are designed to improve stream and riparian habitat, to increase habitat complexity, and to restore natural processes. Many of these projects should benefit bull trout spawning habitat and rearing conditions for young fish.
View more information on our aquatic and riparian habitat restoration program.

Road Improvements and Decommissioning
Roads contributing sediment or blocking fish passage are decommissioned or improved to restore passage, create better habitat for all fish species, and improve water quality. These improvements should benefit bull trout spawning and rearing habitat.
See more information on road improvements and decommissioning.

Aquatic Habitat Research and Monitoring
We conduct research aimed at better understanding habitat needs and general ecological characteristics of bull trout in relation to water operations of the reservoir. Such studies contribute needed information for designing and evaluating habitat restoration and making more informed decisions concerning water supply operations.
See more on our aquatic and riparian research and monitoring program.

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