MITCHELL, SD (Mitchell Now) — As temperatures drop across the region, the South Dakota Game, Fish and Parks is urging lake users and property owners to inspect docks, boat lifts and buoys for zebra mussels before storing equipment for the winter.
“This is an important time of year for monitoring the spread of zebra mussels,” said Tanner Davis, GFP Aquatic Invasive Species coordinator. Davis noted that age-0 mussels — those in their first year — are detectable on equipment left in the water during summer.
Recent inspections by Rapid City fisheries staff led to a positive detection at Sheridan Reservoir, where two age-0 zebra mussels were found in separate locations. The finding makes Sheridan the second zebra mussel–positive waterbody in western South Dakota, joining Pactola Reservoir, which was confirmed in 2022.
Davis said GFP continues to work with federal partners, including the U.S. Fish and Wildlife Service, U.S. Forest Service and Bureau of Reclamation, to conduct inspections and monitoring. In 2025, staff performed 1,614 inspections at Sheridan Reservoir alone, with 14,595 inspections completed across five major West River reservoirs: Belle Fourche, Sheridan, Pactola, Angostura and Shadehill.
Davis emphasized the importance of watercraft inspections and public cooperation. “While these inspections reduce the spread of zebra mussels, inspections are just one tool,” he said.
GFP reminds boaters to “clean, drain, dry” after every outing and encourages dock owners to report any suspicious findings through the agency’s Citizen Monitoring page or by contacting local GFP offices.