Hydrodynamics and sedimentation in bull trout spawning habitats affected by reservoir management in the Cedar River Municipal Watershed, WA
Hydrodynamics and sedimentation in bull trout spawning habitats
Cedar River Municipal Watershed, WA
Reservoir operations have the potential to impact bull trout spawning habitat in the Cedar River. The USGS seeks to understand potential impacts by performing bathymetric, hydrometric, and sediment surveys.
Background
Chester Morse Reservoir, within the Cedar River Municipal Watershed (CRMW), is owned by Seattle Public Utilities and used for power generation and domestic water supply for the city of Seattle. Waterbodies upstream Chester Morse Reservoir support an isolated population of bull trout (Salvelinus confluentus), a species listed as threatened under the Federal Endangered Species Act.
The Issue
Reservoir operations can cause stagnation of flow where the Cedar and Rex Rivers enter the reservoir, reducing the area of spawning habitat for bull trout and the conveyance of flow through egg pockets of nests (redds), which could impact development and survival of their embryos. In addition, floods and associated fluctuations in reservoir levels during the incubation period, in combination with sediment loads delivered by the river, produce episodic sediment deposition and transport that could exacerbate effects of stagnation on incubating embryos.
How USGS will help
To better understand the potential impacts of habitat modification and sedimentation on bull trout caused by reservoir fluctuations, the US Geological Survey Washington Water Science Center will perform bathymetric, hydrometric, and sediment surveys in the lower reaches of bull trout spawning habitats of the Cedar River, upstream of Chester Morse Reservoir. Data from surveys will be used to characterize habitat units used by bull trout for spawning and to differentiate between sites where dissolved oxygen and temperature regimes are suitable to support development of bull trout embryos and where those regimes may be unsuitable.
The results of this project could inform the design of future surveys of bull trout spawning habitat, laboratory experiments on the effects of flow and sediment on bull trout embryo development and survival, and the development of a model to assess how reservoir operation affects the extent and location of suitable spawning habitat for bull trout.
Reservoir operations have the potential to impact bull trout spawning habitat in the Cedar River. The USGS seeks to understand potential impacts by performing bathymetric, hydrometric, and sediment surveys.
Background
Chester Morse Reservoir, within the Cedar River Municipal Watershed (CRMW), is owned by Seattle Public Utilities and used for power generation and domestic water supply for the city of Seattle. Waterbodies upstream Chester Morse Reservoir support an isolated population of bull trout (Salvelinus confluentus), a species listed as threatened under the Federal Endangered Species Act.
The Issue
Reservoir operations can cause stagnation of flow where the Cedar and Rex Rivers enter the reservoir, reducing the area of spawning habitat for bull trout and the conveyance of flow through egg pockets of nests (redds), which could impact development and survival of their embryos. In addition, floods and associated fluctuations in reservoir levels during the incubation period, in combination with sediment loads delivered by the river, produce episodic sediment deposition and transport that could exacerbate effects of stagnation on incubating embryos.
How USGS will help
To better understand the potential impacts of habitat modification and sedimentation on bull trout caused by reservoir fluctuations, the US Geological Survey Washington Water Science Center will perform bathymetric, hydrometric, and sediment surveys in the lower reaches of bull trout spawning habitats of the Cedar River, upstream of Chester Morse Reservoir. Data from surveys will be used to characterize habitat units used by bull trout for spawning and to differentiate between sites where dissolved oxygen and temperature regimes are suitable to support development of bull trout embryos and where those regimes may be unsuitable.
The results of this project could inform the design of future surveys of bull trout spawning habitat, laboratory experiments on the effects of flow and sediment on bull trout embryo development and survival, and the development of a model to assess how reservoir operation affects the extent and location of suitable spawning habitat for bull trout.