18-084 Dworshak water releases to fluctuate during flow-augmentation operations

Published Aug. 7, 2018
AHSAHKA, Idaho -- Dworshak Dam discharge flows will fluctuate between 5,000 cfs and 13,000 cfs throughout the remainder of the summer season to provide cold water from Dworshak Reservoir on the North Fork of the Clearwater River, 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 tailwater (water just below the dam) temperatures at Lower Granite Lock and Dam at 68 degrees Fahrenheit or cooler to benefit fish passage survival of Endangered Species Act (ESA) listed salmonids during summer months, whenever possible.

This process of releasing cool North Fork Clearwater 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 (FCRPS) “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.

The FCRPS Biological Opinion, as written by NOAA-Fisheries, requires the Corps of Engineers, Bureau of Reclamation and Bonneville Power Administration to comply with mandated water-management actions to enhance ESA-listed fish survival on an annual basis:

 Release salmon flow augmentation water to benefit resident fish and salmon.
 Release cold reservoir water to maintain lower Snake River water temperatures below 68 degrees Fahrenheit to improve conditions for adult salmon and steelhead (salmonids) migrating upstream to their spawning grounds.
 Manage total dissolved gasses (TDG) to not exceed 110-percent saturation. When water spills over the dam, gas is entrained and held in solution due to pressure differences in the water at depth. High TDG levels can be stressful for fish. 

Corps park rangers note outdoor-fun opportunities await visitors at Dworshak Reservoir’s shoreline recreation sites and floating recreation docks. Dent Acres campground www.nww.usace.army.mil/Missions/Recreation/Dworshak-Dam-and-Reservoir/Dent-Acres/ is open and available for reservations. The campground usually fills up for holiday weekends, so park managers recommend reserving sites early by calling 1-877-444-6777 or online at recreation.gov. 

More information about all recreation opportunities at Dworshak can be found at www.nww.usace.army.mil/Missions/Recreation/Dworshak-Dam-and-Reservoir/ or call the Dworshak Visitor Center at 208-476-1255.

 “Like” Dworshak’s Facebook page to stay up to date on the latest activities happening at the dam and reservoir www.facebook.com/dworshakdam.  


Release no. 18-084