The Utah Division of Wildlife Resources is coordinating with the U.S. Department of Agriculture Forest Service to conduct waterbody treatments in the High Uintas to restore native Colorado River cutthroat trout. The project involves using rotenone to remove non-native fish species from targeted drainages to ensure the long-term survival of the native trout population.
Scheduled Treatment Locations
The restoration efforts focus on two specific areas within the High Uintas. For the Fall Creek drainage on the south slope, treatments are scheduled to take place from Aug. 3 through Aug. 6, with the area expected to reopen to the public on Aug. 8. On the north slope, biologists will conduct treatments in the North Fork of Sheep Creek on Aug. 19 and Aug. 26.
This year marks the second year of treatment for the Fall Creek drainage, while it is the first year of treatment for the North Fork of Sheep Creek. The North Slope work is part of a broader initiative to treat the upper portions of streams connected to the Sheep Creek canal.
Safety Closures and Restrictions
To ensure public safety during these operations, the Ashley National Forest has issued a temporary area closure. From Aug. 4 through Aug. 6, 2026, the area within 20 feet of Fall Creek, its tributaries, and Anderson and Phinney Lakes will be closed to the public. This prohibition is intended to allow ground crews to work safely in and around the treated waters.
According to the Forest Service, the closure specifically prohibits entering the described area to protect public health and safety. While the waters and areas within 20 feet of them are restricted, all hiking trails and other access points will remain open to public use. The DWR noted that treatment areas will be well-signed and will reopen once rotenone levels are no longer detectable in the streams.
Restoration Methods and Salvage
Biologists use rotenone, a natural substance derived from the roots of a tropical plant in the bean family, to treat the water. While rotenone acts as a respiratory toxin to fish, the DWR stated it is not dangerous to people, pets, or other wildlife when used in the extremely low quantities required for stream and lake treatments.
In the North Fork of Sheep Creek, which currently holds a genetically pure population of Colorado River cutthroat trout, biologists will conduct fish salvage efforts prior to the treatment. All size classes of cutthroat trout that can be removed will be held onsite and released back into the creek once the water has oxidized to help repopulate the stream.
Preventing Species Decline
The necessity of these treatments stems from dramatic declines in native cutthroat trout populations across the West. These declines are driven by habitat loss, competition from non-native species, and spawning with non-native trout. Biologists warn that without intervention, brook trout populations could completely replace cutthroat trout in these areas in less than 20 years.
By removing non-native species—specifically brook trout, non-native cutthroat trout, and rainbow trout—the DWR aims to prevent the species from being listed under the Endangered Species Act. Natalie Boren, the DWR Northeastern Region Aquatics Manager, noted that building robust and resilient populations across the landscape will help ensure the species persists well into the future.
Future Stocking and Angling
The long-term goals for the Fall Creek drainage depend on the success of this year's efforts. If the treatment is deemed successful, the DWR plans to stock Colorado River cutthroat trout into both Phinney Lake and Anderson Lake in 2027.
Beyond conservation, the project aims to meet increasing angling preferences. Recent surveys have shown an increased preference for cutthroat trout among anglers. DWR Regional Sportfish Biologist Carsen Hinkhouse noted that while the efforts are targeted at a handful of waters, they ensure native fish remain on the landscape while providing diverse angling opportunities.
Angling and Information
The Uinta Mountains contain over 1,000 lakes and hundreds of miles of stream. While these specific treatments involve removing brook trout, the DWR maintains that anglers can still find them in thousands of other streams and lakes throughout the mountains.
The DWR continues to provide information on various fishing opportunities through its Fish Utah interactive map. For specific inquiries regarding the treatments, the DWR Vernal office can be reached at 435-781-9453.
Legal Penalties
The Ashley National Forest Order regarding the Fall Creek, Anderson, and Phinney Lakes closure is effective from Aug. 4, 2026, at 7:00 a.m. through Aug. 6, 2026, at 7:00 p.m., unless rescinded. Violations of the order are punishable as a Class B misdemeanor, which may include fines of up to $5,000 for individuals and $10,000 for organizations, or imprisonment for up to six months.
