As of Wednesday, August 8, 2018
Dworshak Dam discharge flows will fluctuate between 5,000 cfs (cubic feet per second) and 13,000 cfs throughout the remainder of the summer season to provide cold water, reducing downstream river water temperatures for migrating salmon and steelhead, according to U.S. Army Corps of Engineers water-management officials at the Walla Walla District.
Dworshak’s cold-water releases help the Corps maintain temperatures in the tailwater – the water just below the dam – at Lower Granite at 68° or cooler to benefit fish passage survival of Endangered Species Act listed salmonids during summer months, whenever possible.
This process of releasing cool North Fork Clearwater River water from Dworshak Reservoir to improve fish passage in the warmer water of the Snake River is part of the Federal Columbia River System’s “salmon flow augmentation” program. The Corps implements this part of the program annually, starting during the summer when water temperatures increase, and ending in early fall when water temperatures begin to cool naturally. The flow augmentation program allows blending of this cooler water with the warmer water arriving from the upper Snake River as it passes through Lower Granite Lock and Dam.