In 1990, Utah used the world’s largest rotenone treatment on Strawberry Reservoir

In August 1990, Utah wildlife officials carried out one of the largest chemical fish-removal projects in fisheries history, wiping out almost every fish in Utah’s Strawberry Reservoir to save its collapsing ecosystem. The operation, led by the Utah Division of Wildlife Resources (UDWR) and described in publications from the American Fisheries Society and UDWR research reports, removed more than 99 per cent of the lake’s total fish biomass. By clearing out the non-native fish, biologists were able to rebuild the food web and create a healthier sport fishery that later produced more than 715,000 angler catches a year. Located 23 miles east of Heber City, the high-elevation reservoir had long been one of the Intermountain West’s best cold-water fishing destinations. But by the late 1980s, large numbers of introduced Utah chub (Gila atraria) and redside shiners had overwhelmed native game fish. They consumed much of the available plankton and contributed to a major decline in trout numbers.Overwhelmed reservoir needed a drastic resetWildlife managers had already tried a smaller rotenone treatment at the original Strawberry Reservoir in 1961. But when Soldier Creek Dam expanded the rese...