Zebra mussels found in Becker County's Big Cormorant Lake

Zebra mussels have been discovered in Big Cormorant Lake in northwest Minnesota's Becker County, state natural resources officials said Monday.

A three-day search by state and county officials found three live adult zebra mussels in different areas of the popular lake, smaller than 1 inch in size. While the numbers discovered are low, the zebra mussels aren't concentrated in one place so treatment "does not appear to be an option," the Minnesota Department of Natural resources said in a statement.

The search for mussels came after a July 15 report from a property owner who saw suspected zebra mussels. A DNR search found the shells of about 60 dead zebra mussels on a pontoon lift, the agency said.

"DNR staff, the property owner and the lake service provider determined the lift was taken out of Crystal Lake in Otter Tail County last fall and had been out of the water for at least eight months before being placed in Big Cormorant Lake," the DNR said, adding, "While the source of the introduction of zebra mussels cannot be confirmed, it is obvious that the lift was not the source."

Agency officials cautioned lakeshore property owners, though, that "anyone who purchases water-related equipment must carefully inspect the equipment for all aquatic invasive species before putting it in any body of water."

More than 200 Minnesota lakes and rivers are now confirmed with zebra mussels, an invasive species that can push out native mussels. They can also cause more algae and weed growth — they filter the lake water, allowing sunlight to penetrate more deeply. They attach to boats, making it easy for them to travel and contaminate other waters.

Zebra mussels were first discovered in Becker County last summer in Lake Melissa, near Detroit Lakes, Minn. Shortly after, the pests were also found in nearby Pickerel Lake.