Migrating juvenile salmon and steelhead (smolts) are often diverted into irrigation ditches. Fish screens are located in ditches to keep fish out of irrigated fields. When fish encounter a screen (revolving drum) they are guided back to the river through a plastic pipe. 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.