Warming waters: Chinook salmon in hot water
… Once abundant, Chinook have been devastated by habitat loss, water diversions from the rivers where they spawn and drought. If they are to recover, the salmon will need improved spawning grounds and more floodplain nursery habitat. They also need more cold water. And in 2023 and 2024, both exceptionally wet years, they got it—until, that is, they didn’t. Water temperatures in the middle Sacramento River soared to lethal levels this spring, exceeding basic environmental objectives and threatening salmon born last summer and fall. The temperature troubles can be traced upstream to Lake Shasta, California’s largest reservoir. The lake is almost full—typically a great boon for fish downstream. But its water is also unusually warm this year, according to local irrigation districts, who say this has produced similar, and unavoidable, temperature profiles in the river downstream.
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