Zebra mussels confirmed in Big Lake and Mitchell Lake in Sherburne County

October 15, 2020

The Minnesota Department of Natural Resources has confirmed reports of zebra mussels in Big Lake and Mitchell Lake, two adjacent lakes in the city of Big Lake in Sherburne County. The lakes are connected by a channel that allows boat traffic.

The DNR confirmed a report from city staff of a zebra mussel near the public fishing pier on Big Lake. A DNR inspection revealed zebra mussels near the public access on Mitchell Lake.

When removing equipment for seasonal storage, lake property owners should carefully check boats and trailers, docks and boat lifts, and all other water-related equipment for invasive species.

While it’s always important to look for invasive species on boats, docks and other equipment, it is especially important at this time of year. Several new zebra mussel confirmations in recent years were initially reported by people removing docks, boats and boat lifts.

Minnesota law requires that docks and lifts remain out of the water for at least 21 days after removal from a waterbody before they can be placed into another body of water. In addition, anyone who transports a dock or lift from a shoreline property to another location for storage or repair may need a permit, to help prevent the spread of aquatic invasive species.

Whether or not a lake is listed for any invasive species, 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.
  • 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 an area DNR aquatic invasive species specialist if they think they have found zebra mussels or any other invasive species that has not already been confirmed in a lake.

More information is available at mndnr.gov/ais.