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Dworshak Dumping Cold Water

by Eric Barker
Lewiston Tribune, July 12, 2003

Annual drawdown begins in effort to help salmon in lower Snake River

Dworshak Reservoir has begun its annual slide that will see it 80 feet below full pool by the end of summer.

The U.S. Army Corps of Engineers started releasing water from the reservoir Sunday to cool the lower Snake River and help threatened juvenile fall chinook on their way to the ocean.

Hot weather has pushed temperatures in the lower Snake River reservoirs to the high 60s and low 70s and prompted the start of annual water releases. Temperatures higher than 68 degrees are considered harmful to salmon.

The cold water from the Clearwater River is intended to mix with the Snake River. However, the mixing takes several miles before it is complete.

"Where we really see the difference is downstream of Lower Granite (Dam, about 30 miles west of Lewiston)," said Cindy Henricksen of the Reservoir Control Center at Portland. "That is because this cold water tends to stay at the bottom of the river and as the water goes through the power house (at the dam) the power house takes the cold water and mixes it up."

The Snake River was 72 degrees at the Anatone gauge south of Clarkston Friday and 68 degrees below Lower Granite Dam after completely mixing with the Clearwater.

The flows from Dworshak Reservoir were slowly ramped up to about 14,000 cubic feet per second by Thursday and will stay at that level at least until July 20. The flows could stay at 14,000 cfs until the reservoir reaches a level of 80 feet below full pool, likely sometime in late August, according Henricksen. Or the water releases could be slowly scaled back in late July and August so there is some cold water available in September.

The Columbia River Inter-Tribal Fish Commission, Nez Perce Tribe and the state of Idaho have asked the corps to conserve some water for September when there are still some juvenile fall chinook lingering in the river and also returning adult fall chinook and steelhead. But the Oregon Department of Fish and Wildlife and the U.S. Fish and Wildlife Service have asked that the flows stay steady at 14,000 cfs until the water is gone.

The issue will be debated Wednesday at a meeting of fish and river managers from state and federal agencies, as well as Indian tribes, known as the Technical Management Team. The now annual debate pits managers who want to use all of the water when most of the young fish are migrating versus those that want to save some water for later migrating fish and returning adults.

The team meets weekly during the spring and summer to decide how the river will be managed to protect threatened and endangered salmon and steelhead.

Related Pages:
EPA Changes Permit for Potlatch by Eric Barker Lewiston Tribune 7/10/3

Eric Barker
Dworshak Dumping Cold Water
Lewiston Tribune, July 12, 2003

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