VERNAL, Utah (ABC4) — The Division of Wildlife Resources will be conducting treatments to waterbodies in the High Uintas to help restore native cutthroat trout.

The treatments consist of adding rotenone to the waterbodies. Rotenone is a natural substance that will kill non-native trout. According to DWR, rotenone is a respiratory toxin to fish but in the low quantities used to treat streams and lakes, is not dangerous to people, pets, or other wildlife.

However, while rotenone is not toxic to humans in low quantities, the public should avoid the area during the treatments, in order to allow the DWR biologists to safely and effectively complete the projects, the DWR reported.

DWR Biologists will be conducting treatments in the following areas:

  • Oweep Creek drainage (south slope) From July 31 to Aug. 4.
    • The area should reopen to the public on Aug. 6.
  • South Fork Sheep Creek (north slope) from Aug. 28-30.
    • The area should reopen to the public on Sept. 4.
  • Daggett, Penguin, Upper Anson, and Lower Anson lakes (north slope) from Aug. 28-29.
    • The area should reopen to the public around Sept. 20.
  • Porcupine Lake (south slope) from July 31 to Aug. 4.
    • The area should reopen to the public around Aug. 18.

“The temporary closure of the treatment area only affects treated waters and prohibits the public from entering the water and obtaining drinking water from sources in the treatment area. All hiking trails and other access will remain open to public use,” DWR Northeastern Region Outreach Manager Tonya Kieffer-Selby said. “The treatment areas will be well signed and will reopen after the treatment process is over and rotenone levels are no longer detectable in the streams.”

According to the DWR, the rotenone treatments are done to help the native fish and ensure cutthroat trout populations improve. The decline in cutthroat trout is due to habitat loss, breeding with non-native trout, as well as competition from non-native trout.

The rotenone treatments will remove the brook trout, non-native cutthroat trout, and rainbow trout found in the streams. According to the DWR, without intervention, biologists predict the brook trout could completely replace cutthroat trout in these areas in less than 20 years.

“As the trustee and guardian of wildlife in Utah, we’re conducting Colorado River cutthroat trout restoration work across the fish’s native range,” DWR Regional Sportfish Biologist Bryan Engelbert said. “The activities will protect the species, while also providing people with great areas to fish for these native fish.”

Following the treatments, biologists plan to restock all waterbodies with native cutthroat trout. Dagget, Penguin, and Anson lakes (upper and lower) will be restocked in 2024, and the South Fork of Sheep Creek will be restocked in 2025.

Although brook trout are being removed from the treatment areas, according to the DWR, they will still be available in thousands of streams and lakes through the Uinta Mountains.

For more information about fishing opportunities, and areas where specific breeds are found, you can visit the interactive Utah Fish Planner map on the DWR website.