Glacier National Park to move forward with Gunsight Lake trout project

Glacier National Park will move forward with plans to restore native trout to a lake on the eastern side of the park.

The National Park Service last week approved plans to poison Gunsight Lake to kill non-native rainbow trout living there, according to a news release. Once the treatment is over, officials will restock the lake with native westslope cutthroat trout, bull trout and mountain whitefish. 

Officials will use rotenone to treat the lake. Rotenone is an EPA-approved piscicide that’s often used for projects like this one. It decomposes naturally with sunlight and water movement, but officials will also use a neutralizing agent to detoxify the water. 

Park officials wrote in the release that the project will reduce the risk of hybridization between cutthroat and rainbow trout, and will provide cutthroat and bull trout with habitat clear of non-native fish. 

The release said the work will be done in late August or early September. It will result in the closure of the area around the treatment, and a likely one-week closure of Gunsight Pass Trail. That closure would extend from Reynolds Campground Junction to just east of Gunsight Pass. 

The Gunsight Lake wilderness campground will close on Sept. 1 until next spring. 

The National Park Service took public comments on an environmental assessment of the project in the spring.