How Fish Screens Work Saving Idaho's Salmon and Steelhead Chinook salmon and trout migrate 900 miles from the Pacific Ocean up the Columbia, Snake and Salmon Rivers to spawn. The young fish live one to three years in the streams before migrating downstream to the ocean. Fish screens are located in ditches to keep fish out of irrigated fields.
Paddle wheels provide power to rotate the drum screen.
The rotation of the drum screen allows the water to wash debris off the drum. Fish screens are built through a cooperative program funded by National Marine Fisheries Service and Bonneville Power Administration. The Idaho Department of Fish and Game constructs and maintains the screens in cooperation with local water users.