| Irrigation
Diversion Fish Screening |
Helping to Save the Bull
Trout,
Montana's Largest and Rarest Native Trout A diversion structure on the North Fork of the
Blackfoot River funneled bull trout during their downstream migration into an irrigation
canal. Native fish evolved with secondary channels or oxbows that eventually returned to
the river. Irrigation canals resemble secondary channels; however most do not return to
the river, leaving the fish high and dry in the irrigated fields. |
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| The
U.S. Fish and Wildlife Service and Montana Department of Fish, Wildlife and Parks
biologists surveyed the canal for bull trout presence. Electro-shocking turned up a
large number of juvenile bull trout and adult fish as large as ten pounds in the
irrigation canal. A fish
friendly irrigation structure was installed on the canal in 1995. Screened drums allow
water to flow through. Drums are turned by electric motors which also operate water jets
that prevent debris buildup on the screens. Bull trout follow the canal downstream,
encounter the screened drums, and continue downstream via the channel, back to the North
Fork.
In 1996, electro-shocking found the
screen to be 100% efficient in keeping fish out of the irrigation canal. Four similar
structures have also been placed on the North Fork of the Blackfoot River. |
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Return to the North Fork of the Blackfoot River
Montana
Partners for Fish and Wildlife
Regional Partners for Fish &
Wildlife Home Page
Mountain-Prairie Region
U.S. Fish and Wildlife Service |
