Glacier National Park officials are seeking public comment for a westslope cutthroat and bull trout preservation project at Gunsight Lake.

The proposal calls for the removal of non-native rainbow trout from Gunsight Lake and reestablish it as a secure habitat for westslope cutthroat trout and bull trout.

According to a release from park officials, the effort’s aims are to remove the risk of hybridization with downstream native trout, provide them with a habitat safe from the threats of hybridization and climate change, and support native trout genetics throughout the St. Mary River drainage.

Public comment is available through June 14. The environmental assessment is available for public review and comment for 30 days on the National Park Service’s Planning, Environment and Public Comment website at parkplanning.nps.gov/GunsightLake.

Non-native rainbow trout would be removed from Gunsight Lake using an EPA registered and approved fish toxicant, rotenone, according to the proposal. While rotenone degrades naturally with sunlight and water movement, detoxification would be hastened with a neutralizing agent.

The neutralizing agent, potassium permanganate, is widely used for the treatment of municipal drinking water and wastewater. Both rotenone and potassium permanganate would dissipate with no detectable long-term changes to water quality, officials said.

Native fish, including westslope cutthroat trout and bull trout, are not currently present in Gunsight Lake. Following the removal of the non-native rainbow trout, genetically pure westslope cutthroat trout and bull trout would be translocated into Gunsight Lake, likely by helicopter.

Activities would begin in early September, with application in late summer or early fall to reduce the likelihood of non-target organisms being present.

The treatment area and Gunsight Pass Trail would be temporarily closed to the public during rotenone application. The Gunsight Lake wilderness campground would be closed to camping from Sept. 1, 2023 until spring of 2024.

In 2019, Glacier National Park in partnership with Montana Fish, Wildlife and Parks, the U.S. Fish and Wildlife Service and Glacier National Park Conservancy, undertook a similar project in the Camas Creek drainage removing non-native Yellowstone cutthroat trout from Camas and Evangeline Lakes and translocating native westslope cutthroat trout and bull trout to both lakes.

The environmental assessment evaluates impacts to westslope cutthroat trout, bull trout, amphibians, aquatic macroinvertebrates, zooplankton, grizzly bears, common loons and other water birds, water quality, recommended wilderness, natural soundscapes and visitor use and experience.

Comments can be posted online at parkplanning.nps.gov/GunsightLake or sent by mail to Superintendent, Glacier National Park, Attn: Gunsight Lake EA, P.O. Box 128, West Glacier, Montana, 59936.

Reporter Taylor Inman can be reached at 406-758-4433 or by emailing [email protected].