The Minnesota Department of Natural Resources says zebra mussel larvae, or veligers, have been found in one of Minnesota's most popular lakes.
The Duluth News Tribune reports Lake Winnibigoshish is one of more than 80 lakes and rivers across the state with zebra mussels.
In northern Minnesota, only a handful of lakes are known to be infested.
Officials stress that no adult zebra mussels have been found, but the presence of larvae suggests a reproducing population somewhere in the lake, according to the Associated Press.
Zebra mussels can have a damaging effect on a lake's ecosystem and, if not controlled, could eventually take a toll on Minnesota's fishing industry.
The DNR says it's not clear exactly how the invasive species crept into Winnibigoshish, but officials continue to stress that boaters and anglers be extra vigilant in ensuring their boats and other equipment are clean before leaving a lake access.