Since construction of the Yellowtail Dam in 1966, Montana’s Bighorn River has fostered a premier tailwater fishery recognized by fly-fisherman for its year-round cold, clear waters and prolific populations of fast-growing wild trout.
However, in addition to creating a blue-water trout fishery, the construction of the dam strongly impacted the natural flow regime of the river channel – negatively affecting the downstream habitat of which the tailwater fishery depends.
Over the past few decades, the Bighorn River has become increasingly disconnected from its side channels. Changes in natural flow volumes and decreases in overall flow variability have led to sediment deposition and vegetation encroachment at side channel entrances, effectively isolating them from the main river. In result, the Bighorn River has become increasingly channelized, offering less complex habitat options for wild trout to fulfil their necessary life stages in.
The Bighorn River Alliance (BHRA), a nonprofit group dedicated to the protection of the Bighorn River, understands that side channel habitats are vital contributors to the health of the Bighorn wild trout fishery. Since 2019 the organization has focused its research efforts to assess, map and survey disconnected, or low functioning side channels that could be restored back to the main channel through mechanical excavation.
“The idea is to explore how, with the help of periodic mechanical excavation, we can restore the Bighorn River to a more natural state that benefits the downstream river ecosystem,” says executive director Anne Marie Emery.
“The reconnection of side channel habitat to the main river not only helps the fishery by providing trout access to critical spawning and rearing habitats, but also helps increase the overall resiliency of the river in lieu of changing climate conditions by providing thermal refuge for trout during low flow years, and helping spread out, and slow down the river during high flow years.”
As of fall 2023, the Bighorn River Alliance has effectively increased the resiliency of the mighty Bighorn through the successful restoration of 7 Bighorn Side channels, adding over 3 miles of complex habitat back to the river and its wild trout, while concurrently monitoring restored habitats to assess macroinvertebrate colonization and fish use.
The group will restore an additional 4-6 channels in the fall of 2024, making one of the largest side channel restoration efforts to date.
The Bighorn River Side Channel Activation project is made possible funding received from the BHRA membership, AFFTA, Montana Trout Foundation, Montana Fish, Wildlife & Park Future Fisheries fund and the USFWS Great Plains Fish Habitat Partnership fund. To learn more about this work and to support the BHRA visit bighornriveralliance.org.
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