Zebra mussels confirmed in Pine Mountain Lake in Cass County

July 2, 2021


The Minnesota Department of Natural Resources has confirmed a report of zebra mussels in Pine Mountain Lake, adjacent to Backus in Cass County.

A swimmer contacted the DNR after finding a zebra mussel attached to a native mussel on a sandbar along the southern shoreline of the lake. DNR invasive species specialists found three more zebra mussels during a snorkel search in the same area.

“It’s helpful when lake users contact us if they find what might be an invasive species that’s new to a lake,” said Heidi Wolf, DNR invasive species unit supervisor. “Early detection is important, because it can help prevent spread to other lakes.”

Whether or not a lake is listed as infested, Minnesota law requires boaters and anglers 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.

Some invasive species are small and difficult to see at the access. To remove or kill them, take one or more of the following precautions before moving to another waterbody:     

  • Spray with high-pressure water.
  • Rinse with very hot water (120 degrees for at least two minutes or 140 degrees for at least 10 seconds).
  • Dry for at least five days.

Zebra mussels can compete with native species for food and habitat, cut the feet of swimmers, reduce the performance of boat motors, and cause expensive damage to water intake pipes.

People should contact a Minnesota DNR aquatic invasive species specialist if they think they have found zebra mussels or any other invasive species.

More information is available at mndnr.gov/ais.