The Minnesota Department of Natural Resources has confirmed the presence of the invasive algae starry stonewort in Middle Cullen Lake, near Nisswa in Crow Wing County.

Minnesota DNR staff, who were conducting a curly-leaf pondweed survey, discovered starry stonewort about 100 feet from the Middle Cullen Lake public access. A follow-up survey is being conducted to determine the extent of starry stonewort distribution in the lake.

Middle Cullen Lake is part of the Cullen chain of lakes, with several connected lakes and other lakes in close proximity. The DNR has updated signage at the lake’s public access and provided decontamination and expanded watercraft inspections, which were in place for the fishing opener weekend.

Starry stonewort is usually identified by the star-shaped white bulbils for which it is named. These bulbils typically don’t become visible until late summer but were observed on the starry stonewort in Middle Cullen Lake. The early visibility of bulbils might be due to unusually warm winter temperatures and below-average snowfall this past winter.

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 29 water bodies in Minnesota. It was first confirmed in Minnesota in 2015.

Starry stonewort is an algae that looks like some native aquatic plants. Information on how to identify starry stonewort can be found on the DNR 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 gear 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, trailers and gear – find free stations on the courtesy decontamination webpage of the DNR website.
• Spray watercraft, trailers and gear 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, trailers and gear for at least five days before using in another water body.