The U.S. Army Corps of Engineers is alerting Willamette Valley residents that it will begin drawing down reservoirs backed up behind some of its 13 dams in the river system, an action designed to aid the downstream migration of salmon and steelhead through the dams, but also one that has increased downstream turbidity that impacts city drinking water.

Anticipating extra turbidity and an interruption of the clean drinking water it withdraws from the North Santiam River, the City of Salem declared a state of emergency at its City Council meeting last week. The expected turbidity is due to the U.S. Army Corps of Engineers’ deep drawdown next year of its reservoir backed up behind Detroit Dam to aid juvenile salmon and steelhead passage, particularly for salmon and steelhead listed as threatened under the federal Endangered Species Act.

Due to lower-than-normal precipitation in May and an early snowmelt in the Northwest, there will be less water available for salmon and steelhead this summer in the Columbia and Snake river basins as water supply forecasts are continuing their downward slide.

Higher flows from Libby Dam designed to encourage endangered white sturgeon to move up into spawning areas on the Kootenai River downstream in Idaho and British Columbia began last week, the U.S. Army Corps of Engineers announced.