Use of rotenone to combat invasive fish in Utah sparks controversy

The Utah Division of Wildlife Resources conducted a rotenone application against invasive brook trout in an approximately 5-kilometer section of Mill Creek in Salt Lake County, in order to protect the habitat of the native Bonneville cutthroat trout.

Rotenone, a substance that affects the respiratory system of fish, is widely used in the western states of the US to control invasive species. During the application, a special substance was also introduced to neutralize the effect of the chemical. The work was carried out in coordination with the US Forest Service, the US Fish and Wildlife Service, and Trout Unlimited.

Concerns were raised on social media that rotenone might be linked to Parkinson's disease. Although 2025 research indicates that some pesticides may be associated with the risk of Parkinson's, it is not scientifically proven that rotenone directly causes this disease. The Utah Division of Wildlife Resources stated that the concentration used was below 50 parts per billion and complied with the safety standards of the US Environmental Protection Agency. Regional fisheries manager Chris Crockett stated that the application met all safety requirements.