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Starry stonewort infestations have been found in three more Minnesota lakes, including the popular Lake Winnibigoshish, which flows into the Mississippi River, state conservation officials said Friday. 

The Minnesota Department of Natural Resources 

 and said it's weighing next steps to battle the invasive species, a grass-like algae that produce dense vegetative mats that can wreak havoc with boats and fish spawning grounds, and choke out native plants.

The DNR is investigating whether the algae have spread out of Winnibigoshish into the Mississippi River and other downstream lakes. Besides Lake Winnibigoshish in Itasca and Cass counties, starry stonewort was confirmed in Moose Lake in Beltrami County and Rice Lake in Stearns County.  

After missing early signs, DNR working to hit new lake invader hard

Officials acknowledged "current treatment options are limited" for Lake Winnibigoshish and Moose Lake given the extensive infestation. The focus now is on checking the spread.

Identifying the species has been part of the challenge. Starry stonewort looks a lot like a native algae called chara, so much so that even the experts missed the invasive plants arrival in Minnesota. 

The DNR said it recently investigated reports of starry stonewort that have turned out to be false.

"The telltale star-shaped bulbils for which it is named typically don't appear until late in the season," DNR invasive species specialist Tim Plude said in a statement. "If people see it in June or July, they'll see what looks like heavy weed growth, and the bulbils aren't easily visible until later in the year. They typically emerge in August and into the fall, which is why these new cases are being found now and why it's a good time for everyone to look for it."

Conservation officials last week began an "aggressive treatment" of isolated infestations on Big Turtle Lake and Upper Red Lake in northern Minnesota, and treatment options are being discussed for 

Starry stonewort is typically spread by lake users who transport fragments of the plant from an infested body of water. 

The DNR again reminded boaters and anglers to follow Minnesota laws to prevent the spread of aquatic invasive species, including cleaning aquatic plants and animals from watercraft, along with mud and debris, which may carry starry stonewort bulbils.

Environmental News

MPR News Staff

Author

Starry stonewort infestations have been found in three more lakes, including Lake Winnibigoshish, which flows into the Mississippi River. The DNR is weighing next steps to fight the invader, which could wreak havoc on boaters.

Invasive lake algae surface in Itasca, Beltrami, Stearns counties

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