Zebra mussel infestation a first for Morrison County

Zebra mussel shells covered a dock
Zebra mussel shells covered a dock on Lake Mille Lacs on May 6, 2015.
Dan Kraker | MPR News file

Zebra mussels have been confirmed in Fish Trap Lake near Motley, Minn., the state Department of Natural Resources said Monday.

Fish Trap is the first lake in Morrison County to be confirmed with the invasive pests, officials said in a statement.

On June 30, a lake user reported a zebra mussel attached to a submerged tree branch near shore that was later confirmed by the DNR. On Thursday, agency staff "found an established population of adult zebra mussels in widespread areas of the lake," making it a poor candidate for treatment, the agency said.

More detailed surveys of Fish Trap Lake will be conducted this week.

More than 200 Minnesota lakes and rivers are now infested 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.

"This new infestation underscores the need for continued diligence in complying with the state's laws to prevent and curb the spread of invasive species," Christine Jurek, DNR invasive species specialist, said in a statement.

The "vast majority" of Minnesota lakes are not infested by any aquatic invasive species, the department emphasized.