South Fork of the Snake River

Reconnecting and Restoring a Native Trout Treasure

Since 2000, Trout Unlimited has worked in the South Fork of the Snake River drainage of eastern Idaho--this storied tailwater below Palisades Reservoir is home to dry-fly-loving Yellowstone cutthroat trout, and it's always been a trophy trout destination. But, in the 1990s, non-native rainbow trout begain to hybridze in earnest with the river's native cutthroats, threatening the genetic integrity of the South Fork's signature fish. TU quickly realized that, in order to protect the river's native fish, it first needed to reconnect lost tributary habitat that cutthroats historically used for spawning.

TU began an ambitious project on the river that included priceless partnerships with landowners, local, state and federal agencies and volunteers from the local TU chapter, who helped with everything from planting willows to building fence to working with elected and appointed officials to increase the understanding of the challenges facing the river.

Today, just over a decade later, there are weirs on every major tributary of the South Fork that prevent non-native rainbows from moving upstream to spawn with cutthroats during the spring migration. Two streams--Garden Creek and Pritchard Creek--have been reconnected to the river and, in most years, have year-round flows for both spawning and rearing. On Rainey Creek, TU worked with more than a dozen landowners from where the creek enters the river upstream to the boundary with Targhee National Forest to screen irrigation ditches, economize water use and improve in-stream habitat. The end result is dependable year-round water in Rainey Creek, which gives native cutthroats the opportunity to migrate upstream to spawn, and then the chance to get back to the river's mainstem, where anglers can pursue trophy-sized trout.

The South Fork is one of TU's many success stories, and it's proof that, with collaboration toward a common cause, we can restore degraded habitat and make fishing better. 

Collaboration Makes Fishing Better

By working with local landowners and showing them the benefits of improving native trout habitat along their stretches of stream, TU has economized water use, prevent native cutthroats from being pulled into irrigation ditches and, in the long run, made fishing better throughout the South Fork system. 

It helps, of course, that we have a firm understanding of the fishery, the land and the people within the drainage. We've worked with local, state and federal agencies to address challenges on both private and public land. We've directed private and public funding toward productive projects that have benefits on many levels--not just for fish or for anglers. We've managed to turn small donations into matching funds, and we acquired larger grants based on our proven investments and techniques. 

The end result is a robust wild trout fishery with a secure future for native Yellowstone cutthroat trout--and the opportunity to catch them.

• TU helped install four weirs on South Fork spawning streams that only allow native Yellowstone cutthroats to pass and spawn without worrying about rainbows mingling with native trout on their redds. 

• We worked with dozens of landowners, negotiating dozens of stream diversion improvements.

• We reconnected two small tributaries to the river that had rechanneled and dewatered for half a century. Today, both streams supporting spawning Yellowstone cutthroat trout.

Matt Woodard

Chris Hunt, Director of Communications