The Minnesota Department of Natural Resources has confirmed the presence of zebra mussels and starry stonewort in Anna Lake, near Underwood in Otter Tail County.
A lake property owner contacted the DNR after finding zebra mussels on a concrete block near a boat lift in Anna Lake. DNR staff found additional zebra mussels in the lake.
While searching for zebra mussels near the public water access, DNR staff also found several small patches of starry stonewort. Staff will conduct additional surveys to determine the extent of starry stonewort and will work with local entities to assess potential management options.
Starry stonewort is usually identified by the star-shaped white bulb-like structures on the plant for which it is named. These bulbils typically become visible in late summer. People can find more information about how to identify starry stonewort on the DNR website.
Since it was first found in Minnesota in 2015, starry stonewort has been confirmed in 36 waterbodies in the state. Starry stonewort can form dense mats, which can interfere with recreational uses of a lake and compete with native plants. The algae primarily spreads when fragments have not been properly cleaned from water-related equipment.
Starry stonewort has never been eradicated from any U.S. lake or river, but treatment or careful removal from waterbodies can help reduce the risk of spread and relieve associated nuisance impacts. Early detection is key to effective management.
Whether or not a lake has any invasive species, Minnesota law also 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, starry stonewort or any other invasive species that was not already known to be in the waterbody.
More information is available on the aquatic invasive species page of the DNR website.