The Bureau of Reclamation will begin its annual “flip-flop” operation after August 20th to aid in successful spawning and incubation of chinook salmon eggs, as well as to improve winter reservoir storage for farmers in the Yakima basin.

Reclamation urges those recreating or working along Yakima basin rivers to exercise caution, especially in the Yakima River near Thorp. In particular, river goers and fishermen should avoid areas where spillway water flows into the river, portage around buoys, and stay out of dangerously turbulent flows.

The process is slated to begin diverting water down the Kittitas Reclamation District’s spillway #1146 into the Yakima River, near Thorp, the week of September 4. The Bureau of Reclamation will be placing Buoys and warning signs in the Yakima River by September 6. Those warning signs will remain in place until mid-October, after the flow from spillway #1146 has ended.

Meanwhile, flows out of the Keechelus and Cle Elum reservoirs, in the upper Yakima River basin, will gradually decrease. Conversely, flows from Kachess and Rimrock reservoirs will increase. This operation is also expected to affect flows in the Tieton and Naches rivers, as well as the upper Yakima, Cle Elum, and Kachess rivers in the upper Yakima basin. This is where the term flip-flop comes into play.

Flows below Cle Elum Reservoir are expected to decrease to a low of about 180 cubic feet per second by September 15th, or sooner. Also a part of the flip-flop, flows from Rimrock Reservoir are expected to increase from the current flow up to between 1,500 and 2,400 cubic feet per second by mid-September, depending on irrigation demands as well as weather conditions. Flows should be between 900 and 1,500 cubic feet per second during the Labor Day weekend, again, depending on prevailing conditions.

Rimrock outflows will begin decreasing in late September and will decline to 50 cubic feet per second after October 20 (the end of the irrigation season) in order to maintain required downstream minimum flows.

The purpose for this annual flip-flop operation is to maintain relatively low, more natural flows, which are important for chinook salmon spawning in the upper Yakima, Cle Elum, and Bumping rivers.

This will also allow the Bureau of Reclamation to reduce impacts on irrigation water supplies by allowing lower reservoir releases throughout the winter to improve storage for the coming season.

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