Hikers and anglers heading into the High Uintas in August will find two waterways temporarily off-limits as state biologists work to bring back native cutthroat trout. The High Uintas, about an hour east of Park City, are a popular backcountry destination for Summit County residents.

The Utah Division of Wildlife Resources announced Tuesday, July 28, that it will treat the Fall Creek drainage and North Fork Sheep Creek with rotenone, a plant-derived substance that kills non-native fish, clearing the way for Colorado River cutthroat trout to be restocked. The DWR is coordinating with the U.S. Forest Service on the effort.

The Fall Creek drainage on the Uintas' south slope closes Monday, Aug. 3, through Thursday, Aug. 6, with the area expected to reopen Saturday, Aug. 8. North Fork Sheep Creek on the north slope will close Wednesday, Aug. 19, and again Wednesday, Aug. 26.

During closures, no one may enter the water or use it for drinking. The DWR says rotenone is not dangerous to people, pets, or other wildlife in the low concentrations used. All hiking trails and access points remain open, and treatment areas will be clearly signed.

What's being removed and why

The treatments target brook trout, non-native cutthroat trout, and rainbow trout. DWR biologists say that without intervention, brook trout could completely replace cutthroat trout in these drainages in less than 20 years.

For Fall Creek, this is the second year of treatment. North Fork Sheep Creek is getting its first. Two to three treatments is standard protocol for effective restoration, according to the agency.

North Fork Sheep Creek currently holds a genetically pure population of Colorado River cutthroat trout. Biologists plan to salvage those fish before treatment, holding them onsite and releasing them back once rotenone levels drop.

What it means for anglers

The Uinta Mountains host more than 1,000 lakes and hundreds of miles of stream. These treatments affect only a handful of those waters.

"Taking part in this restoration ensures native Colorado River cutthroat trout will remain on the landscape, while also providing a diverse angling opportunity," Carsen Hinkhouse, DWR Regional Sportfish Biologist, said in the agency's July 28 announcement.

If the Fall Creek treatment succeeds, DWR plans to stock Colorado River cutthroat trout into Phinney Lake and Anderson Lake in 2027. The broader effort also aims to keep the species off the federal Endangered Species Act list.

Residents with questions can contact the DWR Vernal office at 435-781-9453. KPCW first reported on the closures Wednesday, July 29.

Upcoming closure dates

• Fall Creek drainage (south slope): Monday, Aug. 3 – Thursday, Aug. 6; reopens Saturday, Aug. 8
• North Fork Sheep Creek (north slope): Wednesday, Aug. 19 and Wednesday, Aug. 26