U.S. Army Corps of Engineers managers at Bonneville Dam have shifted flows around to other turbines to reduce scaling of Idaho’s endangered Snake River sockeye salmon.
The Fish Passage Center observed sockeye losing their slightly larger scales than chinook as they went through the dam last week. In response, the Corps has moved the flows to the south side of the dam so the young fish will go through a different powerhouse, the Columbia Basin Fish and Wildlife News Bulletin reported.
Fish biologists from the states of Washington, Oregon, the tribes and the Fish and Wildlife Service recommended the Corps operate the turbine within one percent of their peak efficiency to reduce sockeye scaling and to spill more water over the dams away from the powerhouses. But Corps officials were confident their configuration would be safe for the 165,000 hatchery sockeye released last week and the 20,000 to 30,000 natural sockeye that left Redfish Lake on the 900-mile trip to the sea.
And the Corps opposes more spill because their manager worry it will increase the nitrogen in the river below the dams to lethal levels. None of the state or tribes objected to their decisions, the Bulletin reported.
The Bulletin’s report is a window into the weekly decision-making process for protecting the endangered salmon during the migration.