The Minnesota Department of Natural Resources (DNR) has confirmed the presence of the invasive algae starry stonewort in four Minnesota lakes. The affected waterbodies are Garfield Lake near Laporte in Hubbard County; Gull Lake, about one mile west of Tenstrike in Beltrami County; Three Island Lake near Turtle River in Beltrami County; and Two Rivers Lake near Holdingford in Stearns County.
The findings come after the annual Starry Trek event in early August, during which state and county staff and volunteers surveyed lakes for starry stonewort and other aquatic invasive species. The Minnesota Aquatic Invasive Species Research Center at the University of Minnesota coordinates the event.
A Hubbard County environmental specialist detected starry stonewort at Garfield Lake near the public access. Volunteers reported the algae at the public accesses of Gull Lake and Three Island Lake. At Two Rivers Lake, DNR specialists conducted a follow-up survey after the initial Starry Trek report, confirming the algae across roughly 1.5 acres near the public access and shoreline. DNR aquatic invasive species specialists plan additional surveys at all four lakes to determine the extent of the infestation and will coordinate with local partners to explore management options.
Starry stonewort is recognized by the star-shaped, white bulb-like structures, or bulbils, that typically become visible in late summer. Since its first detection in Minnesota in 2015, the algae has been confirmed in 35 waterbodies statewide. Starry stonewort can form dense mats that interfere with recreation and compete with native plants. The algae primarily spreads through fragments left on boats or other water equipment that have not been adequately cleaned.
While starry stonewort has never been eradicated from a U.S. lake or river, careful removal or treatment can reduce spread and mitigate nuisance effects. Early detection is critical to effective management.
Minnesota law requires all water users to:
- Clean watercraft, trailers, and equipment to remove aquatic plants and prohibited invasive species.
- Drain all water and leave the drain plugs out during transport.
- Dispose of unused 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 to another waterbody.
Additional recommended precautions include decontaminating watercraft at free stations (mndnr.gov/decon), using high-pressure water or thorough rinsing, and drying equipment for at least five days before use in another lake or river.
Anyone who believes they have found starry stonewort or other invasive species not previously documented in a waterbody should contact a Minnesota DNR aquatic invasive species specialist (mndnr.gov/invasives/ais/contacts.html). More information is available at mndnr.gov/ais.
