Responding to the reasonable and prudent alternative outlined in NOAA Fisheries’ 2008 biological opinion for federal Willamette Valley dams, the U.S. Army Corps of Engineers last week proposed to build a selective withdrawal structure at Detroit Dam at a cost of about $100 to $200 million.The SWS would provide water temperature control downstream of Detroit and Big Cliff dams on the North Santiam River and it would provide downstream juvenile fish passage. The Corps would continue to transport adult chinook salmon and steelhead upstream of both dams where they can spawn naturally.