Starry stonewort confirmed in Lake Carnelian in Stearns County

August 27, 2020


The Minnesota Department of Natural Resources has confirmed the invasive algae starry stonewort in Lake Carnelian, near Kimball in Stearns County.

DNR invasive species specialists confirmed starry stonewort near the public access in Lake Carnelian after a trained volunteer discovered it during the University of Minnesota Extension’s Aug. 15 “Starry Trek” event. Each of the past three years, one Minnesota lake has been newly confirmed with starry stonewort following the annual “Starry Trek” searches for the invasive species. This year, more than 200 trained volunteers searched 235 Minnesota lakes.

Starry stonewort has now been confirmed in 16 of Minnesota’s 11,842 lakes. It was first confirmed in the state in 2015.

The DNR will work with Stearns County and the Stearns County Coalition of Lake Associations to consider management options. Boat inspections have been expanded and follow-up surveys will be conducted to watch for the invasive algae in other parts of the lake.

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

Now is the best time of year to look for starry stonewort, because small white star-shaped bulbils are visible, making it easier to distinguish from other aquatic plants. Information on how to identify starry stonewort is available on the DNR’s website. If people think they’ve found starry stonewort or any other invasive species new to a lake, they should report it to the DNR by contacting their area invasive species specialist.

Starry stonewort is an alga that looks similar to native aquatic plants and can form dense mats, which can interfere with use 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. 

The DNR reminds boaters and anglers to follow Minnesota laws to prevent the spread of aquatic invasive species:

  • Clean aquatic plants and animals from watercraft.
  • Drain all water by removing drain plugs and keep drain plugs out while transporting watercraft.
  • 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, especially after leaving infested waters:   

  • 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.

Details about starry stonewort and other aquatic invasive species are available at mndnr.gov/ais.