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Idaho Fish and Game

fish screen

Salmon Region irrigators asked to contact Fish and Game before turning ditch water on this spring

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FG will get fish screens ready before irrigation begins, which will prevent trapping fish in ditches

To keep fish from getting stranded in irrigation ditches, irrigators who divert water from rivers and streams in the Salmon Region are asked to contact Idaho Fish and Game’s Anadromous Fish Screen Program at 208-756-6022 at least one week prior to turning their water on.

This will allow Fish and Game to get any fish screen in the ditch prepared and operational before irrigation water is needed.  Fish screens let water go through but not fish or debris.  Any fish that enter the screen are directed to an underground bypass pipe and are safely returned to river or stream.  

fish screen
This fish screen is powered by the flow of the ditch water which turns a paddlewheel. The paddlewheel continually rotates the screen drum, which is a hollow tube of metal with small holes that allows only water to pass through. This rotation of the drum and water flow allows debris to pass over the drum and directs fish to a bypass pipe that returns them safely to the river or stream.

The upper Salmon River and many of its tributaries provide critical habitat for Chinook salmon, steelhead, and other fish to spawn and to rear as juveniles.  After hatching, juvenile salmon and steelhead spend one to two years seeking out suitable habitat where they can find food and cover until they migrate downstream to the ocean.  It is during this time, when the young fish are actively migrating, that they are at risk of being diverted into one of the many ditch systems.

Because of the fish screening efforts, all fish are safely returned to the river or stream.  Fish screens not only prevent the loss of Chinook salmon and steelhead, but sockeye salmon, cutthroat trout, rainbow trout, bull trout, and mountain whitefish. 

The success of the fish screening program was measured with a study that counted fish as they were returned back to the river after being diverted.  It was found that in the Lemhi River, up to 88 percent of all migrating juvenile Chinook salmon are diverted into at least one ditch system as they migrate downstream. 

Fortunately, Idaho Fish and Game’s screen program, water users, and area landowners have been working together successfully to prevent the loss of fish into ditch systems for over 65 years.  The Screen Program currently operates and maintains over 281 fish screens that have been installed with the cooperation of local landowners and water users.

Region: Salmon Region