A Minnesota ‘lake killer’ surfaced 11 years ago. There’s still no long-term fix

PAYNESVILLE, Minn. — More than a decade after an aquatic invasive species called starry stonewort was first discovered in Minnesota, it s taking an ecological and economic toll on a growing number of the state s beloved lakes. Nicknamed the lake killer early on, the fast-growing algae can form dense mats that choke out native plants and tangle around boat motors and swimmers legs. Since Minnesota confirmed its first infestation in 2015, it has spread to 40 water bodies, including Six Mile Lake in Cass County, which was confirmed just last week. If caught early, starry stonewort is no longer considered a death sentence for lakes. Authorities, though, say it s never been eradicated from any U.S. lake or river. It remains a costly problem with no permanent cure. Researchers have found that chemical treatments or hand pulling can temporarily reduce the algae s abundance, but don t stop it from regenerating. The problem is evident in Lake Koronis near Paynesville