Salmon protection flows set in mid-Columbia River

EPHRATA — Protective river flows are set for the next seven months in the 51-mile Hanford Reach along the Columbia River, following fall Chinook salmon spawning, the Grant County Public Utility District reported Monday.

Washington Department of Fish and Wildlife and Grant PUD biologists monitored progress of fish spawning with weekly counts of salmon redds, or nests, on the Vernita Bar located on the upstream end of Hanford Reach.

Biologists, using salmon passage counts this fall, estimate between 40,000 to 50,000 fall Chinook spawned in the Hanford Reach. Scientists utilize the Vernita Bar, located four miles downstream from Priest Rapids Dam, as an index area for all fish spawning in the Hanford Reach. Significant spawning activity along this one and a half mile gravel bar provides data on the timing and distribution of fall Chinook activity, said Grant PUD spokesman Gary Garnant.

Redd counts on the Vernita Bar helped biologists determine a minimum Columbia River flow of 70,000 cubic feet per second would be optimum to protect eggs in the river's gravel. The flow established by biologists is maintained through the Hanford Reach spawning area until incubation is complete and the young salmon emerge from their gravel nests in May or June, Garnant said.

The seven mid-Columbia River hydroelectric dams coordinate operations to ensure the salmon eggs remain underwater until the young fish emerge, he said. River conditions, following emergence, are regulated to minimize flow fluctuations during early rearing within the Hanford Reach prior to the young salmons' trip downstream to the Pacific Ocean.

Grant PUD operates Priest Rapids and Wanapum dams to protect listed and non-listed fish species. Fall Chinook operations continue from October through June. Garnant said additional efforts to protect juvenile salmon run from June through August.