Study says drawing down Lower Granite Reservoir during summer could help fish

By Eric Barker
Spokesman Review

Drawing down Lower Granite Reservoir during summer heatwaves could be an effective tool to help sockeye salmon and other protected fish by mitigating high water temperatures, according to analysis performed by the Portland-based Fish Passage Center.

But just as it did in a 1992 experiment, a drawdown would also disrupt barge transportation on the lower Snake River, leave some recreational facilities high and dry, and cause some riverside highways and railroad beds to sag and crack.

At the request of the Nez Perce Tribe and the state of Oregon, the center that is funded by Pacific Northwest hydropower ratepayers analyzed the feasibility of lowering the lower Snake River behind Lower Granite Dam from its present elevation of about 733 feet above sea level to as low as 690 feet. Doing so would reduce the surface area exposed to solar radiation, speed the pace of the river and increase the effectiveness of cold water releases from Dworshak Reservoir. Read More