DULUTH (AP) -- Scientists say a tiny but harmful snail species has taken up residence in the St. Louis River estuary.

Doug Jensen of the University of Minnesota Sea Grant program says the discovery of faucet snails marks a substantial range expansion for the invasive species.

He says they're asking anglers, boaters and waterfowl hunters within the estuary to be especially vigilant about cleaning their boats, waders and other gear before leaving water accesses.

Faucet snails were first noted in Lake Superior in 2010 at Washburn, Wisconsin.

They harbor parasites that can kill waterfowl.

They've been blamed for the deaths of thousands of scaup and coots in the Lake Winnibigoshish area of northern Minnesota.

The Department of Natural Resources says they're also established in the Mississippi River near La Crosse, Wisconsin.