Yellowstone National Park is beginning efforts to restore native westslope cutthroat trout and Arctic grayling in Grayling Creek and its tributaries, located north of West Yellowstone in the Madison River drainage.

An interagency team of biologists will introduce rotenone – a fish toxin – into the streams to remove non-native trout as part of Yellowstone’s Native Fish Conservation Plan and Environmental Assessment, which was approved in May 2011. Rotenone will be applied in small quantities and visitors are advised not to swim in or drink from the streams the week of Aug. 19 through Aug. 30. Warning signs will be posted at all treated areas.

Decades ago, the streams were invaded by non-native brown and rainbow trout. Their presence has contributed to a decline in native cutthroat trout in park lakes, rivers and streams. Only waters within the park will be treated and the project will not impact downstream reaches, according to an Aug. 19 press release.

This year’s treatment is the first in a series that is expected to continue over the next two to three years, until non-native trout have been completely removed from the streams. The park will then reintroduce genetically pure native Arctic grayling and westslope cutthroat trout. The long-term plan is to support native species restoration and for these streams to provide a brood stock population for future restoration efforts in the region.

Find more information on the park’s Native Fish Conservation Plan online at parkplanning.nps.gov/projectHome.cfm?projectID=30504.