Press Release
U.S. Fish and Wildlife Service Issues Final Environmental Assessment for Beaver Dam Notching at Red Rock Lakes National Wildlife Refuge
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LIMA, Mont. — The U.S. Fish and Wildlife Service (Service) has released a Final Environmental Assessment (EA) for Red Rock Lakes National Wildlife Refuge (Refuge). The proposed action is to improve Arctic grayling access to spawning habitat by notching beaver dams in Red Rock Creek (RRC), some of which is within designated wilderness. 

A 30-day public comment period for the draft EA ran from February 1, 2024, through March 1, 2024. The Service received a total of 4,860 comment letters on the proposed action. Many comments were focused on topics outside of the proposed action and planning area. Relevant comments focused on impacts to wilderness, sedimentation, and questioned whether beaver dams do impede grayling. We have updated the final EA to reflect the comments shared during the comment period.

Arctic grayling (Thymallus arcticus; grayling) are a freshwater species of salmonid that reside in open water in clear, cold, medium to large rivers and lakes. The population that resides in the Upper Missouri River drainage in southwestern Montana is one of four remaining populations of Arctic grayling in the contiguous United States still exhibiting the full spectrum of life history behaviors present in historic grayling populations. RRC, located upstream of Upper Red Rock Lake in the Centennial Valley of southwestern Montana, is the primary spawning stream for the Upper Missouri River Arctic grayling population. However, beaver dams have been documented to partially or entirely block grayling movements on RRC, preventing access to spawning habitat. 

Notching will remove a portion of each beaver dam with primitive hand tools to ensure grayling have access to upstream spawning areas. When the population is less than1,000 adults, notching beaver dams would occur each spring prior to grayling spawning. Beavers will typically rebuild these dams over the course of the following summer. No ground disturbance would occur.

A copy of the EA can be reviewed on the Refuge website at: 

Learn more about Red Rock Lakes National Wildlife Refuge at:


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– FWS –

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