BEMIDJI -- Lake Bemidji has an unwelcome guest.

The Minnesota Department of Natural Resources confirmed Thursday that the big lake contains zebra mussels, the invasive species that’s slowly-but-surely spreading across the Great Lakes.

A Lake Bemidji State Park intern was leading a July 20 fishing class near Rocky Point when he discovered one of the troublesome mussels in the belly of a perch, according to Beltrami County and DNR staff. But DNR dives into the lake the following week found no conclusive evidence of the invaders.

An Aug. 19 “plankton tow” found one young zebra mussel -- a “veliger” -- near the north end of the Lake Bemidji, but an Aug. 28 followup dive also found no conclusive evidence.

The infestation wasn’t confirmed until Bruce Anspach, Beltrami County’s aquatic invasive species lake technician, discovered more of the mussels this past Friday, Oct. 26, at the Northwoods lake access and the easternmost Nymore Beach access.

Anspach told the Pioneer he searched 16 more Lake Bemidji locations earlier this week, five of which had zebra mussels. He reported no findings on some connected bodies of water, but DNR staff said they’ll still be listed as infested. Those bodies of water are Lake Marquette, Carr Lake, Lake Irving, Stump Lake and the stretch of the Mississippi River from Stump Lake to Wolf Lake.

Ecologically speaking, the mussels could interfere with Lake Bemidji fish population because they consume the same food as young fish. Anspach expects the mussels to start washing up on the lake’s shores in the next five to eight years, and their sharp shells also could harm beachgoers. Zebra mussels are also known to hamper fishing and clog boating equipment and other infrastructure.

Recreational -- “day use” -- boaters still need to follow the state’s “clean, drain, dry” methodology to prevent the spread of zebra mussels, Anspach said.

“With this new infestation comes even more responsibility to area boaters,” he said. “There is no known management for zebra mussels, so the best practice is to not let them spread.”

Here’s what Minnesotans can do to prevent the spread of zebra mussels, according to the DNR:

Whether or not a lake is listed as infested, state law requires water recreationists to:

Clean watercraft of all aquatic plants and prohibited invasive species.

Drain all water by removing drain plugs and keeping them out during transport.

Dispose of unwanted bait in the trash.

Dry docks, lifts, swim rafts and other equipment for at least 21 days before placing equipment into another water body.

It is important to carefully check docks, boat lifts and other equipment being removed for the season and to contact the DNR if you think you’ve found an invasive species that is new to a lake, department staff said. Minnesota law requires keeping docks and lifts out of the water for at least 21 days before putting them into another body of water.

And the DNR recommends these steps for lake property owners:

Look on the posts, wheels and underwater support bars of docks and lifts, as well as any parts of boats, pontoons and rafts that may have been submerged in water for an extended period.

Hire DNR-permitted lake service provider businesses to install or remove boats, docks, lifts and other water-related equipment. These businesses have received training on Minnesota’s aquatic invasive species laws and many have experience identifying and removing invasive species.

People should contact their area aquatic invasive species specialist if they think they have discovered an invasive species that has not already been confirmed in a lake. Take a photo of any newly discovered invasive species before removing it from equipment.

Save specimens or leave them in place until the DNR can investigate.

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