News release: Zebra mussels confirmed in Union Lake in Douglas County

August 14, 2025


The Minnesota Department of Natural Resources has confirmed the presence of zebra mussels in Union Lake, near Alexandria in Douglas County.

Douglas County invasive species staff found zebra mussels on a settlement sampler at the Union Lake public water access. Settlement samplers are solid surfaces temporarily placed in the water that people can regularly check for attached zebra mussels to aid in detection.

Union Lake is connected to, but upstream, of Burgen Lake, where zebra mussels were confirmed in 2017.

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 waterbody to another.

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

  • Decontaminate watercraft and equipment – find free stations on the courtesy decontamination page of the DNR website.
  • Spray watercraft and equipment with high-pressure water or rinse with water if high-pressure water is not available.
  • Dry watercraft and equipment for at least five days before using in another waterbody.

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

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

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