Image of starry stonewart courtesy MN DNR.

The Minnesota Department of Natural Resources has confirmed the presence of the invasive algae starry stonewort in Long Lake, near Hawick in Kandiyohi County.

DNR staff conducting a survey of algae in Long Lake found starry stonewort at a depth of eight to twelve feet near the west public access on Long Lake.

Follow-up surveys showed the starry stonewort appears to be present in a roughly one-quarter-acre area of the lake near the public access. Available treatment options could include hand pulling, herbicide applications or other methods as appropriate.

Starry stonewort has never been eradicated from any U.S. lake or river, but treatment or careful removal can help reduce the risk of spread and relieve associated nuisance impacts on water-related recreational activities. Early detection is key to effective management.

Starry stonewort has now been confirmed in 24 water bodies in Minnesota. It was first confirmed in Minnesota in 2015.

In late summer and early fall, starry stonewort’s small white star-shaped bulbils become more visible, making it easier to distinguish from other aquatic plants. Information on how to identify starry stonewort can be found on the DNR’s website.

If people think they’ve found starry stonewort or any other invasive species new to a lake or river, they should report it to the DNR by contacting their area invasive species specialist.

Starry stonewort is an algae that looks like some native aquatic plants. It can form dense mats, which can interfere with recreational uses of a lake and compete with native plants. It is most likely spread when fragments have not been properly cleaned from trailered boats, personal watercraft, docks, boat lifts, anchors or other water-related equipment.

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 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.

Funding for the Long Lake algae survey was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR), Project 2021-055: Protecting Minnesota’s Beneficial Macroalgae – All Stoneworts Aren’t Starry.