Salmon Search Over Inside Dam Plumbing

The Army Corps of Engineers has decided to restart a water system that feeds a fish passageway along the north side of Bonneville Dam by the end of the week.

The decision was made after hydroacoutistic testing found few fish in the auxiliary water supply, the corps said Wednesday in a news release.

“This data tells us there are very few adult salmon in the AWS,” biologist Gary Johnson said in the release.

“We’re sad if we lose any fish, but at the same time, it’s essential that we are ready for the steelhead and Chinook fall runs under way now and that will peak in early September.”

The auxiliary water supply provides a swift flow of water in the fish ladders to attract salmon and steelhead. The fish instinctively fight the flow to swim upstream to their spawning beds.

Fish were allowed passage into the water system when gratings were torn out of place by debris carried by spring runoff.

The gratings that keep fish out of the water system have been replaced, and the corps is developing a monitoring plan to make sure they stay there, the news release said.

Johnson said there would not be enough time to drain the auxiliary water system and clean it out before the fall fish runs reach Bonneville.

“We’re confident the north shore fishway, with one fish attraction turbine working, will allow the system to operate successfully and allow continued fish passage until fall,” he said.

Attempts to flush out the system produced just one steelhead, the corps said.