Idaho Grants Dworshak Exemption More Water To Be Spilled At Dam In Effort To Help Salmon Runs

Idaho has granted the National Marine Fisheries Service an exemption to spill more water at Dworshak Dam and exceed the state’s water quality standards.

Officials of that agency and the U.S. Army Corps of Engineers said Friday afternoon they had not received notification of the decision, delaying any increase spillage from behind the Clearwater River dam until today.

The flow would help flush migrating salmon smolts through Snake River reservoirs downstream.

The exemption allows the National Marine Fisheries Service to call for more water from Dworshak until May 5, according to Wallace Cory, Idaho Division of Environmental Quality administrator.

Washington and Oregon have granted similar exemptions.

Both the agency and the Fish Passage Center operated by state and tribal agencies had asked the corps to spill 10,000 cubic feet of water a second from Dworshak.

But the federal Technical Management Team cut that request in half Wednesday.

The team cited Idaho’s water quality standard, which limits dissolved gas levels to 110 percent of normal.

Following that decision, Dworshak began spilling water for the first time since last summer. The spill of about 5,000 cubic feet per second pushed dissolved gas levels in the North Fork of the Clearwater to 109 percent.

The National Marine Fisheries Service plan this spring puts a cap of 120 percent on dissolved gas levels immediately below the dams.

Critics who oppose spilling water contend high gas levels can threaten fish just as divers get the bends.

But fisheries agencies say more water to push the smolts downstream faster promises to benefit the salmon runs more than hurt them.

Idaho Fish and Game biologist Steven Pettit said the states and tribes had asked for more water from Dworshak because cold weather has slowed the melting of snowpacks and the Snake’s flow was dropping.

A large number of young wild chinook salmon and their hatchery cousins were beginning to arrive in Lower Granite Reservoir on the Snake, he said. Biologists hope the extra water from Dworshak will help keep the migration from stalling.