By Montana Grant

Posted: April 21, 2022


Federal and State agencies are moving forward with a plan to remove all fish from Hidden Lake and 50 miles of the Buffalo Creek watershed. These waters can be found Absaroka-Beartooth Wilderness area. This project is part of the Yellowstone National Parks native cutthroat trout population/ restoration plan.

Public comments can be made for the next 45 days and filed with the Forest Service. MTFWP will accept comments for 30 days.

These waters will be treated with rotenone which is a piscicide poison that impacts the fish’s gills. Similar poisonings have occurred in the Upper Gibbon watershed in Yellowstone Park. Genetically pure Yellowstone Cutthroat trout will be stocked into the fishery once other fish have been removed. 

Rotenone is derived from a root of a South American plant. It impacts only organisms with gills. The poison works quickly and does not leave any harmful traces in the dead fish.

Rainbow trout were the first trout to be planted in Hidden Lake. They soon spread throughout the watershed which eventually meanders into Slough Creek, a tributary of Lamar River. Most of Yellowstone’s waters were devoid of fish until being stocked by the National Park Service in the late 1800’s.

There is a natural barrier below Hidden Lake that can keep any other rainbow trout from migrating into the upper watershed. Yellowstone Cutthroat trout have historically not lived in this watershed. Because of the natural barrier, the park can increase cutthroat habitat by 20%.

Hybridization, competition from nonnative species, habitat degradation, and human impacts have threatened the native Cutthroat populations. Warmer water temperatures have also become a threat. This Hidden Lake and Buffalo Creek watershed is ideal for Cutthroat trout and could become a stronghold for this Native species.

Below the cascade waterfalls of Hidden Lake, rainbow trout reproduce with Cutthroats. This area will stay as it is, since Rainbow Trout thrive in the lower Slough Creek, and Lamar River. This watershed is too large to currently address.

More Cutthroat refuges are ongoing.

Montana Grant

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