The Bureau of Reclamation will begin the annual flip-flop operation in the Yakima Basin by gradually reducing flows out of Cle Elum Reservoir in the Upper Yakima River Basin and increasing flows from Rimrock Reservoir in the Tieton and Naches River Basins beginning the week of August 27.

The purpose of the flip-flop operation is to maintain relatively low flows in the spring Chinook salmon spawning areas in the upper Yakima, Cle Elum, and Bumping rivers.

“These lower river flows will be maintained during the winter and successfully keep the egg nests covered,” Yakima Project River Operations Supervisor Chuck Garner said. “Operating the system this way also helps to reduce impacts on irrigation water supply by keeping reservoirs as full as possible for the next season.”

This process also involves diverting water on September 6 down the Kittitas Reclamation District's Spillway 1146 into the Yakima River near Thorp, Wash.

Reclamation will install buoys around the area where Spillway 1146 water enters the Yakima River where they will remain until about October 20. For safety reasons, recreationists are advised to portage around this area and stay out of the turbulent flows.

Beginning around August 28, flows out of Cle Elum Reservoir of about 3,000 cubic-feet-per-second will gradually decrease to about 200 cfs by about September15. Flows from Rimrock Reservoir are expected to increase to over 2,000 cfs by mid-September and could possibly reach 2,500 cfs depending on irrigation demands and weather conditions.

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