Sacramento River below Shasta is warm enough to kill Chinook eggs

Chinook are on the gravel below Shasta Dam, and a lot of those eggs are in water that is too warm to finish the job. Active NorCal reported Sept. 23 that state biologists watching the nests estimated in early September that roughly one in five eggs might not survive. The river has warmed since that estimate. The piece says Chinook eggs start dying once water passes about 53.5°F, and the Sacramento has crossed that line.

San Francisco Baykeeper is blaming how the cold water was spent. The group says the Bureau of Reclamation let too much Shasta Lake water go this spring and summer for Central Valley farms and drew down the cold pool that is supposed to chill the river through spawning. Reclamation's answer, as Active NorCal reports it, is that the bureau is following a temperature plan built with state and federal fishery agencies and is complying with the Endangered Species Act. Conservation groups had already warned in May that heavier releases south would leave the river too warm by fall.

The timing sits on top of a season California just got back. Ocean salmon fishing reopened after three straight years of closure, and the Department of Fish and Wildlife had projected a strong Sacramento return. Warm water on the spawning beds hits the next generation before it reaches the ocean. Shasta Dam, 602 feet and in place since 1945, blocks the cold spring-fed streams near Mount Shasta where these fish used to spawn. The river below the dam is the spawning water they have.

This is a The Gillnet news desk summary, not a reprint.

Source: Active NorCal — California's Biggest River Just Got Too Warm for Its Own Salmon (Sept. 23, 2026).