Little Boy Lake near Longville confirmed for zebra mussels

The Minnesota DNR confirmed zebra mussels in Little Boy Lake near Longville on June 4, 2026, putting a well-used Cass County lake on notice just as peak summer boating begins. For boaters, anglers, dock and lift owners, resort operators, and anyone moving gear between lakes, the message is straightforward: treat this as a confirmed infestation and clean equipment before it leaves the water.

What the DNR confirmed

The DNR said a Cass County invasive species specialist reported a zebra mussel found on a settlement sampler at a private dock. A DNR specialist then found a live zebra mussel during a follow-up search. Outdoor News reported the same finding on June 10 and identified the lake as Little Boy Lake near Longville.

The Longville Chamber of Commerce map places Little Boy Lake about 3.5 miles south of Longville on Highway 54, which makes the finding especially relevant for nearby cabins, launches, resorts, and other lake users in the area.

What readers should do now

Minnesota law requires people to clean watercraft, trailers, and equipment to remove aquatic plants and prohibited invasive species; drain all water and leave drain plugs out during transport; dispose of unwanted bait in the trash; never release bait, plants, or aquarium pets into Minnesota waters; and dry docks, lifts, and rafts for 21 days before moving them to another water body.

The DNR also says people can reduce the risk further by decontaminating watercraft and equipment when possible, using high-pressure water or a rinse if needed, and drying watercraft and equipment for at least five days before using them in another water body. Anyone who thinks they found a new invasive species should contact a DNR aquatic invasive species specialist.

Why it matters locally

The practical impact is local rather than countywide: Little Boy Lake users are the ones who need to pay extra attention to gear that could move zebra mussels to other lakes. For Longville-area residents and visitors, clean-drain-dry is now part of the normal routine at launch ramps, private docks, and seasonal properties.

Sources

• Minnesota DNR news release: Zebra mussels confirmed in Little Boy Lake, Cass County
• Outdoor News report: Zebra mussels confirmed in Little Boy Lake in Cass County
• Longville Chamber of Commerce maps
• Cass County AIS 2026 Prevention and Management document