Cougar drawdown to support out-migrating juvenile salmon

From KLCC: Fishery biologists have found that young Chinook salmon generally swim in the top 20 to 30 feet of the water column. That can pose a problem if the primary method of getting past a dam is deeper.

The Corps of Engineers is lowering Cougar Reservoir about 32 feet below normal winter levels, hoping for the same result they saw at another reservoir.

Cougar Reservoir
Photo by Dave Merwin

“Our draw down at Fall Creek last year, we estimate passed 20-30,000 juvenile Chinook salmon in a matter of days.”

Spokesman Scott Clemans says the Corps physically transports *adult salmon around the dam upstream, but doesn’t provide any specific downstream passage for young fish. Engineers are weighing the option of *constructing fish passage…

“But certainly if we are able to see much higher levels of passage merely by lowering the reservoir level, that seems like a very low-cost alternative to doing something very structural to the dam.”

Officials say downstream residents on the McKenzie will likely not notice any visible change in flow. The Corps aims to keep Cougar water levels low for several weeks.

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