Rotenone in Fisheries: Are the Rewards Worth the Risks?

11. Utah’s Rotenone Sandmix: A Formulation to Maintain Fish Toxicity in Seeps or Springs

Robert L. Spateholts and Leo D. Lentsch

doi: https://doi.org/10.47886/9781888569339.ch11

Abstract.—Sandmix (powdered rotenone-sand-gelatin mixture) proved to be an effective formulation for treating sources of upwelling groundwater that frequently provide refugia for target species during chemical rehabilitation projects. In trials conducted at Strawberry Springs, Utah, in 1988, 0.25 mg/L and 0.35 mg/L (active ingredient based on 24-h flow volume) rotenone applications of sandmix produced 100% mortality of trout fingerlings placed 4,8, 12 and 24 h after application. Mortality was only 0-70% in trials with the same application rates of liquid rotenone and powdered rotenone and water paste. Over 2,500 lbs of powdered rotenone were made into sandmix and applied to more than 450 seeps and springs during the chemical rehabilitation of Strawberry Valley in 1990. The sandmix generally maintained toxic concentrations for at least 12 h.