Second Minnesota lake infested in 2017 by starry stonewort

A second Minnesota lake has been found to have been infested this year with the latest aquatic invasive species.

The state Department of Natural Resources said Monday that starry stonewort has been found in Lake Minnewaska in Pope County. The 7,500-acre lake, the largest in Pope County and a popular spot for anglers and boaters, is the 11th in the state to be infested with the invasive algae since the first infestation was reported in 2015.

The DNR's announcement Monday comes nearly a week after it said Grand Lake in Stearns County was infested, the first lake confirmed with starry stonewort in 2017.

The invasive grows into dense mats that can shroud shallow waters, choke out native plants, and create a wall between fish and their spawning grounds.

Lake Koronis near Paynesville was the first Minnesota lake confirmed to be infested with starry stonewort, in 2015. The invasive has been found in 10 of the 11 infested lakes during the month of August — the best time of year to detect it because the star-shaped bulbils on its root system are most abundant.

Crews discovered starry stonewort in Lake Minnewaska in the narrow marina off the lake's main body, the DNR said. The lake, located in central Minnesota near Glenwood and Starbuck, has already been infested with Eurasian water milfoil and curly-leaf pondweed, according to the Lake Minnewaska Association. Mike Stai, president of the association, declined to comment Monday on the finding of starry stonewort.

At Grand Lake, Scott Palmer of the lake's improvement district, said last week that the district and the DNR would try to treat the 655-acre lake, hoping to make it the first lake in the U.S. to successfully eradicate the algae.

To prevent starry stonewort from spreading to more Minnesota lakes, the DNR reminds boaters to clean off aquatic plants, drain all water and remove drain plugs when transporting boats.

Kelly Smith • 612-673-4141