The Bureau of Reclamation will adjust spring-time operations at its Shasta Dam to benefit endangered winter-run chinook salmon in the Sacramento River during this critically dry water year, including temporarily bypassing power production at its 633-MW hydro powerhouse.
The operation change is coordinated with the National Oceanic Atmospheric Administration Fisheries, Western Area Power Administration, State Water Resources Control Board, and Sacramento River Settlement Contractors to preserve the limited supply of cold-water pool in Shasta Reservoir. No additional water will be released during this temporary adjustment.
The operation adjustment will require the bypass of Shasta Dam‘s powerplant and temperature control device due to the low water elevation in Shasta Reservoir. Beginning April 18, Reclamation will instead release water from the warmer, upper layers of Shasta Reservoir directly through the dam’s river outlets into the Sacramento River. This warmer water, averaging 55 degrees Fahrenheit this time of year, will help maintain Sacramento River flows through the spring and preserve the limited supply of colder water for later in the summer when most critical for endangered winter-run chinook.
The bypass of Shasta Dam’s powerplant means hydropower will not be produced with these water releases and will have a financial impact to Central Valley Project power customers and their planned requirements to meet the state’s clean energy goals. Shasta Dam’s powerplant provides electricity for about 250,000 California households per day. Reclamation is working with WAPA to develop solutions to lessen the impacts to those power customers.
Chinook salmon hatch in streams and river, migrate to the Pacific Ocean where they spend about three years, and then return to their home stream to spawn. When spawning, they make nests in the riverbed gravel, called redds. The survival of the eggs within redds is affected by water flow and temperature, among other factors.
“The only remaining population of winter-run Chinook salmon in the Central Valley is in the Sacramento River downstream of Shasta Dam,” said Dr. David Mooney, Reclamation’s Bay-Delta Office manager. “Last year, despite dry conditions, we effectively shaped cold water for higher survival rates, but other factors reduced survival to very low levels. Protecting egg incubation in this second year will help support this endangered species for the future.”
Reclamation — in coordination with NOAA Fisheries, U.S. Fish and Wildlife Service, California Department of Fish and Wildlife, and Pacific States Marine Fisheries Commission — will monitor and evaluate conditions to ensure this operation adjustment is meeting the intended goal. As the bypass water temperature increases later in the spring, Reclamation will revert to use of the powerplant and temperature control device when winter-run chinook salmon spawn and colder waters are needed. If fisheries conditions show adverse effects from a warmer spring, Reclamation will coordinate with partners to further adjust temperatures during the bypass.