News release: Starry Stonewort confirmed in Clearwater Lake in Wright County

August 28, 2023

The Minnesota Department of Natural Resources has confirmed the presence of the invasive algae starry stonewort in Clearwater Lake, near Annandale in Wright County.

An aquatic vegetation survey company discovered starry stonewort across 1.8 acres of a protected cove on the south side of the east basin of the lake, and a Minnesota DNR invasive species specialist confirmed its presence. The aquatic vegetation survey company and the Minnesota DNR surveyed other areas of the lake and did not find starry stonewort elsewhere in the lake. Available treatment options could include hand pulling, herbicide applications or 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 relieve associated nuisance impacts on water-related recreational activities. Early detection is key to effective management.

Starry stonewort has now been confirmed in 27 water bodies in Minnesota. It was first confirmed in Minnesota in 2015.

Starry stonewort is an algae that looks like some native aquatic plants. 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 Minnesota 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 Minnesota DNR by contacting their area invasive species specialist.

Starry stonewort can form dense mats, which can interfere with recreational uses 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. 

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 waterbody 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.

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