News release: Zebra mussels confirmed in Lake Ann in Chanhassen

July 31, 2023

The Minnesota Department of Natural Resources has confirmed the presence of additional zebra mussels in Lake Ann, in the city of Chanhassen in Carver County.

The Riley Purgatory Bluff Creek Watershed District has conducted annual zebra mussel searches on Lake Ann since a single adult zebra mussel was found on a swimming buoy in September 2020.

On July 12, RPBCWD staff found four adult zebra mussels on a tree branch in shallow water near the swimming beach on the southern edge of the lake. Five additional zebra mussels were found in the same location during a follow-up search. 

No zebra mussels were found during a broader search of other areas of the lake. Because zebra mussels were found only in one specific location, potential treatment options are being considered. The Minnesota DNR permits zebra mussel management projects on a limited basis. Zebra mussels have never been eradicated from any lake or river in the U.S., but treatment options might reduce the risk of further spread. Early detection is key to effective management.

Whether or not a lake has any invasive species, Minnesota law requires people to:

  • Clean watercraft, trailers and equipment to remove aquatic plants and prohibited invasive species.
  • Drain all water and leave drain plugs out during transport.
  • Dispose of unwanted bait in the trash.
  • Never release bait, plants or aquarium pets into Minnesota waters.
  • Dry docks, lifts and rafts for 21 days before moving them from one water body to another.

These additional steps reduce the risk of spreading aquatic invasive species:

  • Decontaminate watercraft and equipment – find free stations on the courtesy decontamination webpage of the Minnesota DNR website.
  • Spray with high-pressure water or rinse with very hot water (120 degrees for at least two minutes or 140 degrees for at least 10 seconds).
  • Dry watercraft and equipment for at least five days before using in another water body.

People should contact a Minnesota DNR aquatic invasive species specialist if they think they have found zebra mussels or any other invasive species that was not already known to be in the water body.

More information is available on the aquatic invasive species page of the Minnesota DNR website.

Back to top