Aggressive treatment of Turtle Lake starry stonewort begins

The Minnesota Department of Natural Resources access on Turtle Lake near Bemidji has been temporarily closed for aggressive treatment of a half-acre of starry stonewort. The access is expected to reopen before Labor Day. A nearby resort owner has volunteered his lake access as a temporary public access site while treatment options are pursued.

A curtain has been installed at the public water access on Turtle Lake (known locally as “Big Turtle”) to confine the affected area for treatment. Contractors will use suction to vacuum up the vegetation and a layer of muddy substrate where starry stonewort fragments may be present. Algae fragments and the tiny star-shaped bulbils for which the plant is named can cause new growth. After the removal of the vegetation and substrate, a copper-based herbicide will be applied to the area in an effort to kill any vegetation or bulbils that could be left.

“The best-case scenario is that starry stonewort will be effectively removed from the lake,” said Heidi Wolf, DNR invasive species unit supervisor. “To date, starry stonewort has not been ‘eradicated’ from an infested lake anywhere in the United States.” On Turtle Lake and Lake Koronis, where another aggressive treatment is taking place, experts hope this approach can be more effective than those previously undertaken elsewhere.

“The DNR appreciates the partnership of Beltrami County and the Turtle River Watershed Association in this treatment effort,” Wolf said. “We also thank Dr. Ken Karol of the New York Botanical Garden for making positive confirmation of the recently-discovered infestations in Beltrami County.”

Starry stonewort are grass-like algae that may produce dense mats, which could interfere with use of the lake. The invasive algae also may choke out native plants.

Starry stonewort is typically spread by lake users who transport fragments of the plant from an infested body of water. Boaters and anglers are reminded to follow Minnesota laws to prevent the spread of aquatic invasive species:

  • Clean aquatic plants and animals from watercraft, trailers and equipment.
  • Drain all water by removing drain plugs and keep drain plugs out while transporting watercraft.
  • Dispose of unwanted bait in the trash.

More information about aquatic invasive species and how to report them is available on the aquatic invasive species page.