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Valley Water rescues, relocates threatened steelhead in Coyote Creek ahead of Anderson Reservoir drawdown

August 28, 2020
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Valley Water biologists rescued federally threatened Central California Coast Steelhead from Coyote Creek recently and relocated them to a more suitable environment in the Coyote watershed.

Valley Water captured Central California Coast Steelhead from Coyote Creek before the drawdown of Anderson Reservoir begins on Oct. 1.  Eighteen biologists participated in the rescue and relocation effort, which started Aug. 17 and ended Aug. 20.

“This is an example of Valley Water’s commitment to protecting sensitive and threatened species like the Central California Coast Steelhead,” said Nai Hsueh, Chair of the Valley Water Board of Directors. “We believe it’s important to make every effort to move these fish into a more beneficial environment.”

Valley Water will begin draining Anderson Reservoir on Oct. 1 to allow for the construction of a new, larger outlet tunnel at Anderson Dam. The tunnel will allow for greater control over water levels, provide additional incidental flood protection, and help the environment.

Draining the reservoir and building the outlet tunnel comes in response to a directive from the Federal Energy Regulatory Commission (FERC), the federal agency that has oversight of Anderson Dam. Valley Water is working to retrofit and strengthen Anderson Dam, home to Santa Clara County’s largest reservoir, so it can safely withstand a strong earthquake.

Anderson Reservoir will gradually be drained to about 3% of capacity. Valley Water will keep water flowing into Coyote Creek by using imported water pumped from San Luis Reservoir. That imported water may be warmer than water that is normally in the creek during the summer and early fall.

“Most fish and the ecosystem will be able to persist in Coyote Creek, because water will continue to flow,” said Lisa Porcella, environmental services manager at Valley Water. “However, the warmer water from San Luis is not ideal for the more sensitive steelhead.”

To help catch the fish, Valley Water reduced the amount of water released into Coyote Creek from Anderson Reservoir. This encouraged the fish to congregate in pools, making it easier for Valley Water biologists to scoop them out of the water. Flows from Anderson Reservoir into Coyote Creek have resumed back to normal.   

Valley Water biologists focused their efforts along a stretch of Coyote Creek which is considered the most likely place to find juvenile steelhead based on habitat and water temperatures.

Valley Water released the captured steelhead to different locations within the Coyote watershed that are anticipated to have better habitat in the coming months. The locations have been pre-selected by Valley Water in consultation with the California Dept. of Fish and Wildlife (CDFW) and the National Marine Fisheries Service (NMFS).

All other species of fish will remain in place in Coyote Creek as water is released from Anderson and San Luis reservoirs.

Valley Water captured only juvenile steelhead or resident rainbow trout (fish that do not migrate to the ocean). Valley Water did not locate any adult steelhead, as they typically live in the ocean during this month.

The rescue and relocation plan was developed in collaboration with CDFW and NMFS. As part of that plan, Valley Water released higher flows of water from Anderson Dam into Coyote Creek in May of 2020 to encourage remaining juvenile steelhead to migrate out of Coyote Creek and into the ocean. This pulse of water provided an extra opportunity for juvenile steelhead to make it out of the creek and into the ocean, thus limiting the number of fish that might be affected by the reservoir draining. 

A variety of native fish are found in Anderson Reservoir, including rainbow trout, Sacramento sucker, tule perch, hitch and prickly sculpin. Non-native fish in the reservoir include largemouth bass, bluegill, black crappie, white catfish, common carp, threadfin shad, and inland silverside. Following the full drawdown of the reservoir later this year, the remaining reservoir pool, which will roughly be the size of Stevens Creek Reservoir, will continue to support the fish in the reservoir.

For more information about the Anderson Dam Seismic Retrofit project, please visit https://www.valleywater.org/anderson-dam-project


Valley Water manages an integrated water resources system that includes the supply of clean, safe water, flood protection and stewardship of streams on behalf of Santa Clara County's 2 million residents. The district effectively manages 10 dams and surface water reservoirs, three water treatment plants, an advanced recycled water purification center, a state-of-the-art water quality laboratory, nearly 400 acres of groundwater recharge ponds and more than 275 miles of streams. We provide wholesale water and groundwater management services to local municipalities and private water retailers who deliver drinking water directly to homes and businesses in Santa Clara County.