The Minnesota Department of Natural Resources has confirmed the invasive algae starry stonewort in Leech Lake in Cass County.

A company removing aquatic plants contacted the DNR when its staff suspected finding starry stonewort near Anderson’s Cove Resort in Steamboat Bay. A DNR invasive species specialist confirmed starry stonewort throughout the marina, around and under docks and boats. 

Leech Lake is largely within Leech Lake Band of Ojibwe reservation boundaries. The DNR Invasive Species Program is working with the Leech Lake Band of Ojibwe, the Leech Lake Association, property owners and local governments to discuss management options. State funds are available for an immediate response that could include hand pulling, herbicide applications and other methods as appropriate.

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

With the addition of Leech Lake, starry stonewort has now been confirmed in 18 of Minnesota’s 11,842 lakes, including nearby Cass Lake and Lake Winnibigoshish. It was first confirmed in Minnesota in 2015.

As summer progresses, 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 in another part of Leech Lake, or any invasive species new to a lake, they should report it to the DNR by contacting their area invasive species specialist.

About 200 Minnesota lakes are searched annually for starry stonewort during the “Starry Trek” event coordinated by University of Minnesota Extension, scheduled for Aug. 21 this year. In each of the past three years, one Minnesota lake has been newly confirmed with starry stonewort as a result of the annual “Starry Trek” searches.

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 water 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.