Lower Snake River ‘temperature diet’ looks to shed degrees

By Jennifer Yachnin | 09/13/2024 01:29 PM EDT

Amid a debate over the future of four dams on the river, the Army Corps of Engineers and Washington state officials are trying to figure out how to cool off the water to boost salmon migration.

A row of sockeye salmon under water on rocks.

Snake River sockeye salmon travel nearly 900 miles from the Pacific Ocean to the Sawtooth Valley lakes in Idaho. NOAA

Federal and state officials plan to spend the next year figuring out how to address the “heat pollution” in the Lower Snake River, ratcheting down summer water temperatures in a bid to bolster a struggling population of fish.

Flows in the 140-mile stretch of river in southeastern Washington state regularly spike above 70 degrees Fahrenheit in the summer months. The warm water creates unfavorable conditions for migrating salmon and steelhead, further complicating an already arduous journey that many will not survive.

This plan won’t address what all agree is one big factor contributing to the hot water: four dams that tribes and environmental advocates want to see come down. Instead, the Army Corps of Engineers, which operates the dams, and the Washington State Department of Ecology, are searching for other ways to put the region on a “temperature diet.”

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Those efforts could result in lowering the levels of some or all of the four reservoirs at different times, among the options to speed water through the system to keep temperatures within acceptable ranges.

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