Invasive Mudsnails Found in Bear Creek

Researchers discovered invasive New Zealand mudsnails in a Kent County, Michigan waterway that feeds the Thornapple River.

Updated on Nov. 9, 2026 in Environmental

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Should Michigan spend more public money trying to control invasive species in its waterways?

Coldwater River Watershed Council volunteers found invasive New Zealand mudsnails in Bear Creek in Kent County, Michigan. The discovery marks the species' first spread into the southern Lower Peninsula of Michigan, and established populations cannot be eradicated.

Why it matters

A single mudsnail can produce 200 clones annually, and in some western states populations have reached about 300,000 snails per square meter. Because the snails have already spread to several Michigan rivers, the Grand Rapids area's waterways face a growing containment challenge.

Field discovery by volunteer monitors documents the species at Bear Creek, and a single mudsnail can produce 200 clones annually, with western-state populations reaching about 300,000 snails per square meter. The extent of the local population and its downstream spread remain unknown.

The players

Coldwater River Watershed Council

A local watershed group whose volunteers located the mudsnails in Bear Creek while monitoring the region's waterways.

The details

The mudsnails were probably carried into the Great Lakes in ships' ballast water in 1991 and have since been found in several Michigan rivers. Michigan's recorded mudsnails appear to be entirely female, and their protective shells have a tiny trapdoor that lets some survive passage through a fish's digestive system.

1991: Mudsnails probably introduced to the Great Lakes through ballast water.
November 9, 2026: Report published on the Bear Creek discovery.

Big Picture

The discovery extends the ballast-water pathway by which the species entered the Great Lakes in 1991 into inland Michigan streams. Because established mudsnail populations cannot be eradicated, the find is a containment problem rather than a removal one.

Anglers, boaters, and waders in the region can spread the snails on gear, so cleaning equipment matters. Freezing, hot water, and prolonged air exposure can kill snails on equipment.

The takeaway

Thoroughly drying, freezing, or heat-treating waders and boats after use can help keep mudsnails from moving to new waters. Because established populations cannot be eradicated, prevention is the most effective tool available to residents.