Faucet Snail


The faucet snail (Bithynia tentaculata) is a small invasive snail, native to Europe that is dark-brown to black in color, up to ½” in length, and features 4-6 whorls. It has a cover or ‘operculum’ on its shell opening with concentric circle markings in adults and spiral markings in juveniles.

How It Spreads

The faucet snail can spread by attaching to aquatic plants, boats, anchors, and other recreational gear and equipment. It may also spread to new waterbodies via migrating waterfowl that have ingested infected snails,and potentially by the downstream movement of submerged vegetation to which they’ve attached in high flows. The gear and equipment of waterfowl hunters are also a potential vector of transport and spread, particularly between the Mississippi River and Lower Wisconsin River sloughs.

Impacts to Rivers

The environmental impacts of the faucet snail are significant. The snail has been linked to the deaths of an estimated 75,000-100,000 waterfowl in the Upper Mississippi Wildlife Refuge since 2002. It can also out-compete native snails that are a critical food source for fish, birds, and other wildlife.

The snail can also cause negative economic impacts. In 2006,66,000 Wisconsin waterfowl hunters spent an estimated $19 million on trip expenditures and equipment, and contributed to a total output of approximately $26 million associated with waterfowl hunting, including 444 jobs.


River Alliance of Wisconsin Factsheet (Lower Wisconsin River Basin AIS Strategic Plan)

Distribution in Wisconsin’s Lakes and Rivers (Wisconsin Department of Natural Resources)

United States Geological Survey Factsheet