Invasive zebra mussels have once again invaded a Minnesota lake, this one just 10 miles from the Boundary Waters Canoe Area Wilderness, according to the Minnesota Department of Natural Resources.
Biologists from the Fond du Lac Band of Chippewa reported the discovery after retrieving an aluminum can in Crooked Lake encrusted with the marine creatures, The Jamestown Sun reported. The area is about 70 miles from the nearest inland lake where zebra mussels had been known to exist.
So far, workers from the Minnesota Department of Natural Resources (DNR) and the US Forest Service have not found other mussels, despite follow-up searches using underwater cameras, sediment sample checks, plant rakes and walking surveys along the lake.
The lake is being declared as infested, and crews will continue to search connected waters, including Artlip Lake, Houghtailing Creek, Wanless Creek and the Cross River.
"Nothing anymore is a surprise, but it is a disappointment," Rich Rezanka, aquatic invasive species specialist for the DNR, told the Star Tribune. "We've tried hard with prevention methods. Someone wasn't paying attention."
"[The zebra mussels] didn't drive up there or hitchhike up there. They got moved up there," he added.
Zebra mussels filter nutrients from lake water, leaving water clearer but with less food for fish and native species. Lakes in the Boundary Waters area are already hot fishing spots and low in nutrients, so a zebra mussel infestation there would likely harm fishing, Rezanka said.
The invasive pests first popped up in Minnesota's Duluth-Superior Harbor in 1989, and have since spread throughout the Great Lakes and Mississippi River watershed, as well as to numerous inland lakes and streams.
Despite being fingernail-sized, they are the only freshwater mussel that can attach to objects and clog water intakes and form masses on boats, nets, docks, swim platforms and boat lifts, as well as cut up swimmers' feet.
Boaters are urged to clean boat hulls and pull drain plugs when moving boats from lake to lake.
Signs will also be posted with special rules considering the situation and will prohibit the movement of any water, fish, weeds or bait out of the lake.