News release: Starry stonewort confirmed in Bowen Lake in Cass County, Turtle River Lake in Beltrami County

August 15, 2022


The Minnesota Department of Natural Resources has confirmed the invasive algae starry stonewort in Bowen Lake, near Backus in Cass County and in Turtle River Lake, near the city of Turtle River in Beltrami County. 

DNR staff conducting an aquatic plant survey found starry stonewort in Bowen Lake. Beltrami County Environmental Services staff found starry stonewort at Turtle River Lake during early detection surveys at area accesses. Follow-up surveys are being conducted to determine the extent of starry stonewort distribution in these lakes.

The Bowen Lake sample was confirmed by New York Botanical Garden scientist Kenneth G. Karol as part of a statewide study to assess the distribution and diversity of native and non-native macroalgae. Funding for this research was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources.

The DNR Invasive Species Program, local governments, lake associations and private contractors often work together on initial responses and any ongoing management actions. Funds are available for an immediate response at Bowen and Turtle River lakes that could include hand pulling, herbicide applications and 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 provide alleviate nuisance impacts on water-related recreational activities. Early detection is key to effective management.

Starry stonewort has now been confirmed in 21 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 alga that looks similar to native aquatic plants and can form dense mats, which can interfere with lake use 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 water body 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.

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