Zebra mussels clinging to docks and boat lifts being pulled from Minnesota waterways for the season have been confirmed across the state in recent days.
The latest lakes to be infested with the thumbnail-sized mollusks include: Lake Riley in Carver County, Koetter Lake in Stearns County, Mound Lake in Todd County, Crookneck Lake in Morrison County and Elkhorn Lake in Kandiyohi County.
The Minnesota Department of Natural Resources (DNR) confirmed these lakes have been infested with about 100 zebra mussels.
The most were in Lake Riley, where the DNR found 91 mollusks. The other lakes did not see such a big infestation.
The detailed search started when a Lake Riley business contacted the DNR after finding juvenile zebra mussels on water equipment. Staff from the Riley Purgatory Bluff Creek Watershed District found zebra mussels at five locations around the lake’s perimeter.
Property owners on Koetter Lake and Mound Lake alerted the DNR after finding several adult zebra mussels on their water equipment. The DNR confirmed several half-inch mollusks in Koetter Lake, and they are also “widely distributed” in Mound Lake.
Earlier this summer, DNR staff searched Crookneck Lake after a report of a single zebra mussel but came up empty. However, the DNR Parks and Trails staff found an adult zebra mussel on a dock being removed for the season.
A zebra mussel was found on the northwest side of Elkhorn Lake, and a subsequent dive search of the lake found no other invasive species. DNR staff then found several adult zebra mussels while searching equipment in the water on the other sides of the lake.
Zebra mussels can drastically change a lake’s plant community and food supply. The tiny mussels reproduce quickly and multiply into the millions, filtering out nutrients in the water. Their sharp shells cut the feet of swimmers, foul boat motors and damage water pipes.
The DNR reminds boaters that state law requires them to clean watercraft and trailers of aquatic plants and prohibited invasive species, drain all water by removing drain plugs and keeping them out during transport, and dispose of unwanted bait in the trash.
Owners should also spray their craft with high-pressure water, rinse with hot water and allow to dry for at least five days before moving a boat to another waterway.
At least 46 of the 62 Minnesota lakes added to the DNR’s infested-water list in 2018 had zebra mussels.