Invasive algae found in two more Minnesota lakes

The Department of Natural Resources says starry stonewort invasive algae has spread to Upper Red Lake and Cass Lake in northern Minnesota.

Starry stonewort is a fast growing grass-like algae that forms thick mats capable of snarling boat traffic and crowding out native plants. It was found in Minnesota for the first time last year in a lake near Alexandria, and earlier this month the DNR reported an infestation in Turtle Lake near Bemidji.

The DNR typically advises people to carefully clean boats and equipment to avoid spreading invasive species. Because starry stonewort is relatively new to the state it can be hard to identify, according to DNR invasive species unit supervisor Heidi Wolf.

"The more people hear about the issue, the more eyes are out there and people are looking for it," she said. "So definitely we will be looking very hard and now towards the end of the season it actually grows more abundantly and it's a little bit easier to identify."

Wolf says no one has successfully eradicated starry stonewort from a lake in the U.S. But she says because the new infestations are all small, the agency will aggressively try to eradicate them.

"We can't predict what it will do in a specific water body or how much of a nuisance it might be," she said. "But we're definitely concerned about it."

Additional research is underway to find more effective treatments for the invasive algae, which was likely introduced to the U.S. when a ship dumped ballast water in the Great Lakes in the 1970s.

The U.S. Geological Survey identifies starry stonewort infestations in New York, Pennsylvania, Vermont, Michigan, Indiana, Wisconsin and Minnesota.