Fall Removals Offer an Ideal Time to Inspect Docks for Zebra Mussels

November 14, 2025

As cooler temperatures begin to take hold, late fall presents an ideal opportunity to inspect docks, boat lifts, and buoys for zebra mussels.

"This is an important time of year for monitoring the spread of zebra mussels," said Tanner Davis, Aquatic Invasive Species Coordinator. "Age-0 mussels, or those in their first year of growth, will be able to be detected on structures that have been placed in the water throughout the summer months."

Inspecting docks and buoys as they are removed for winter is an important step for zebra mussel monitoring, and these efforts by Rapid City fisheries staff led to a positive detection on Sheridan Reservoir in western South Dakota.

"Two age-0 zebra mussels were detected on separate locations within the reservoir, which makes Sheridan Lake the second zebra mussel positive water in western South Dakota," continued Davis. "Pactola Reservoir was the first confirmed western waterbody in 2022, and GFP has been working closely with the US Fish and Wildlife Service, US Forest Service, and Bureau of Reclamation to conduct both watercraft inspections and monitor for zebra mussels."

Specifically in 2025, there were 1,614 inspections at Sheridan Lake alone. Combined, 14,595 inspections were conducted on all five major reservoirs, including Belle Fourche, Sheridan, Pactola, Angostura, and Shadehill, operating 10 hours each day, 7 days per week.

"These watercraft inspections are possible with the aid of federal grants and our partnership with conservation districts in western South Dakota," elaborated Davis. "While these inspections reduce the spread of zebra mussels, inspections are just one tool to slow the spread of aquatic invasive species."

Individuals are reminded to clean, drain, dry every time they are on the water. This includes pulling all boat plugs, draining all water, and drying equipment that has been submerged in water.

"As equipment removals continue across the state, we'll continue to inspect for zebra mussels and ask for assistance from private dock owners as well," concluded Davis. "If you find something you suspect is a zebra mussel or other AIS species, please submit a suspect report on the Citizen Monitoring page, contact your local or regional GFP office, or contact me directly at Tanner.Davis@state.sd.us."

 

View All News