Press Release
Red Rock Lakes National Wildlife Refuge Releases Final Environmental Assessment for Arctic Grayling Overwintering Habitat
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LIMA, Mont. — The U.S. Fish and Wildlife Service (Service) has published a Final Environmental Assessment (EA) and Findings of No Significant Impact (FONSI) to improve winter oxygen levels for the conservation of Arctic grayling (Thymallus arcticus) in Upper Red Rock Lake (URRL) within Red Rock Lakes National Wildlife Refuge (Refuge).  

Grayling are a species of salmonid that reside in the Upper Missouri River drainage in southwestern Montana. Grayling are indigenous to the Upper Missouri River and currently persist only in the Big Hole River drainage and in the Centennial Valley. This population is the only lake-dwelling population of grayling remaining in the lower 48 United States. Much of the Centennial Valley grayling population migrates into URRL for the winter. Grayling in the URRL are genetically distinct from populations elsewhere in the Upper Missouri River and have recently undergone significant declines in abundance.  Therefore, the primary winter habitat in URRL is vital for the species' continued existence. 

The Service has decided to proceed with installing a pipeline from Shambow Pond to URRL (Alternative D) to improve overwinter habitat that will ensure long-term, self-sustaining persistence of grayling in URRL and the Upper Missouri River. The Service will construct a buried, gravity flow diversion pipeline during the summer of 2023 to convey water from East Shambow Creek and Shambow Pond to the center of URRL during the winter months. This alternative was selected as it benefits grayling while minimizing impacts to wilderness. Once installed the pipeline and its components will primarily be underground and underwater, nearly eliminating its visual impact. There are no pumps or motors creating noise, so the sound impact is also negligible.  


“The Service and our partners support this alternative. It strikes a balance between effectiveness for the population and minimal impact on wilderness,” said Refuge Manager Mike Bryant, “We hope it provides the safety net this rare population of fish needs to recover and thrive into the future.” 

The Draft EA presented six alternatives for improving overwinter survival of grayling in URRL and assessed respective impacts on natural and recreational resources. A 30-day public comment period on the Draft EA closed on March 28, 2023. The Service received over 71 individual substantive comments and addressed over 34 different topics in the Final EA. Frequent comment topics included: impacts to grayling from grazing, impacts to grayling from angling, and potential impacts to the Wilderness Area from the different alternatives. Moving forward with the selected alternative allows for balancing grayling conservation with wilderness values. 

The Final EA and associated documentation are available in the Refuge library at

The Minimum Requirements Analysis associated with the Wilderness Act is available at

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