New Zealand Mudsnails

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Great blue heron eating a fish
New Zealand mud snails with penny

New Zealand mudsnails are attacking Kelsey and Valley creeks. These invasive snails may be tiny, but they reproduce at anything but a snail’s pace, spreading rapidly by cloning, and damaging habitat as they spread. The snails have little nutritional value and crowd out native invertebrates that fish and other aquatic life eat.

New Zealand mudsnails have been found in only one other stream in the Lake Washington area, to date — Thornton Creek in Seattle. Able to live for weeks on damp gear, the snails can be easily transported by people, which is probably how they got to Bellevue.

Help stop the snails' spread

There is no way to control these fast-growing snails once established. That’s the bad news. The good news is that residents can help prevent their spread.

The City of Bellevue has developed a mobile application for tracking New Zealand mudsnails in Bellevue and surrounding areas. The mudsnail map shows where the snails have been observed and their infestation levels. (Map does not work with Microsoft Edge.)

Check out the types of infestation levels in Bellevue and snail identification information. The Washington Department of Fish and Wildlife offers more information on New Zealand mudsnails and proper decontamination procedures.