Friend or foe? Barrier rebuilt to protect native Wyoming fish from invasive species

The People's Canal irrigation diversion in southwestern Wyoming was recently rebuilt to help protect native fish in the Henry's Fork from invasive species. Photo by Hillary Walrath

By Hillary Walrath

In the world of trout conservation, the term “fish barrier” is sometimes seen as an enemy to native trout. However, in a world filled with invasive species, those barriers are often the only thing protecting trout. Such is the case on the Henry’s Fork, a tributary to the Green River, in southwestern Wyoming

The Henry’s Fork flows from the northern Uinta Mountains in Utah into Wyoming and drains into Flaming Gorge Reservoir near the town of Manila, Utah. Fisherfolk often drive across this little river on their way to bigger waters, such as Flaming Gorge or the Green River below below the dam. Although this river is easy to miss, it is home to several conservation populations of Colorado River cutthroat trout and other native aquatic species. Flaming Gorge Reservoir, on the other hand, contains non-native species, including the predatory and invasive burbot.

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A Colorado River cutthroat trout from the Henry's Fork River above the People's Canal. Photo by Hillary Walrath

The People’s Canal irrigation diversion is the only thing preventing the highly piscivorous (aka trout-eating machine) burbot from accessing over 100 river miles in the Henry’s Fork. Trout Unlimited and the Wyoming Game and Fish Dept. sampled above and below the diversion and the results were striking. Above the diversion, they found healthy Colorado River cutthroat, bluehead and flannelmouth suckers and a variety of other native fish species. Immediately below the diversion, they found burbot and spawning rainbow trout.

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Highly predatory and invasive burbot were found below the People's Canal diversion on the Henry's Fork.  Photo by Hillary Walrath.

The worrisome issue was that the diversion was wooden, antiquated and could potentially fail with the next big flood event. So, Trout Unlimited partnered with the People’s Canal Irrigation Company, Wyoming Game and Fish Dept., Wyoming Wildlife and Natural Resource Trust Fund, National Fish and Wildlife Foundation, Bureau of Land Management, Wyoming Landscape Conservation Initiative, Natural Resources Conservation Service, and both the Seedskadee and Upper Bear River Chapters of Trout Unlimited to improve the old structure to one of the largest fish barriers in the state of Wyoming.

A time lapse slideshow showing reconstruction of the People's Canal Irrigation Diversion on the Henry's Fork in southwest Wyoming. By Hillary Walrath.

Construction of the new diversion lasted from October to the middle of November and was completed just in in time for winter to make its appearance. This project has been years in the making and wouldn’t have been possible without every single partner. Thanks to their efforts, the future of this incredible fishery looks merry and bright.

Hillary Walrath works as the Salinity Control Coordinator for the Henry's Fork of the Green River for Trout Unlimited. She is based in Green River, Wyoming.