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Dworshak Dam Releases Cold Water to Help Protect Salmon During Inland Northwest Heat by Staff Daily Fly, July 27, 2026

Salmon and steelhead migrate most efficiently in water around 65 degrees

AHSAHKA, ID -- As summer heat continues across the Inland Northwest, the U.S. Army Corps of Engineers is using Dworshak Dam near Orofino to help cool portions of the Snake River for migrating salmon and steelhead.

According to the Corps, the Clearwater River near Orofino reached 79.7 degrees on Saturday, July 25, while the Snake River near Anatone climbed to 74.4 degrees. The two rivers meet at Lewiston, where the warmer water can create stressful conditions for fish migrating upstream.

To help reduce river temperatures, the Corps released cold water from the bottom of Dworshak Reservoir on July 25. The release kept water temperatures behind Lower Granite Dam at 66.1 degrees or lower, according to the agency.

Salmon and steelhead migrate most efficiently in water around 65 degrees, according to U.S. Army Corps of Engineers fish biologist Chris Peery. As water temperatures rise above about 68 degrees, fish begin showing signs of stress, migration delays and, at higher temperatures, increased mortality.

Dworshak Dam's deep reservoir allows managers to release water that remains about 42 degrees year-round. The Corps works with the National Marine Fisheries Service and the U.S. Fish and Wildlife Service to determine when cold-water releases are needed to improve conditions in the lower Snake River during the summer.

Officials said the releases cannot eliminate warm river temperatures throughout the system because many factors influence water temperatures, including weather, drought, snowpack, streamflows and upstream conditions. However, they said the releases provide valuable flexibility to help maintain cooler water in portions of the Clearwater and lower Snake rivers during periods of extreme summer heat.

Dworshak Dam, located on the North Fork Clearwater River near Orofino, is the third-tallest dam in the United States and stores more than 3.4 million acre-feet of water. In addition to flood risk management and power generation, the reservoir plays a key role in supporting fish migration by providing a source of cold water during the warmest months of the year.

Related Sites:
Warming streams are pushing young salmon beyond their limits: new research by Charlotte Fisher, University of British Columbia, 6/29/26
Heat broils eastern Washington, Idaho as federal water managers seek to salve river temperatures. Enter Dworshak Dam -- calm, cool (water) and collected. Northwest Division USACE, 7/27/26