• New Zealand Mudsnails and Other Unwanted Invasive Species

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    New Zealand Mudsnails and Zebra Mussels
    Photo of New Zealand Mudsnails comparing size to one penny

    New Zealand Mudsnails are attacking the Kelsey Creek Watershed. 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.

    • Learn more about New Zealand Mudsnails and how they arrived in Bellevue through this Story Map.
    • The mudsnail map shows where the snails have been observed and their infestation levels. 

    Help prevent the spread of snails

    New Zealand Mudsnails can hitch a ride on boots, clothes, animal fur, and other equipment and be carried by streams and stormwater to new locations. The mudsnails are tiny and easily mistaken for a small pebble. Once established, there is no way to control these fast-growing snails. That’s the bad news. The good news is that residents can help prevent their spread.

    Please take these steps to help stop the spread of New Zealand Mudsnails in Bellevue:
    • Keep pets out of streams and lakes. If your dog wades into the water, carefully dry off or brush him/her on dry land. Focus on paws and bellies.
    • Carefully scrub off any debris or mud from waders, boots, or clothing that has come into contact with streams, lakes or mud. Freeze these items overnightor let them completely dry out for 48 hours. The Mudsnails can survive out of the water for weeks.
    • Drain any stream or lake water collected in gear or equipment before you leave a site. Rinse off the gear in clean, potable water away from any body of water and let it dry completely for 48 hours before reuse. Do not flush rinse water down the storm drain—it’s connected to our creeks and can reintroduce Mudsnails.

    Other invasive species

    Photo of zebra mussels on moss, courtesy Missouri Dept of Conservation

    Not only are Bellevue streams at risk from New Zealand Mudsnails, but other aquatic invasive species could arrive at any time. These include invasive zebra mussels, recently discovered in certain brands of purchased aquarium moss.

    To prevent the spread of zebra mussels:
    • The Washington Department of Fish and Wildlife and the Washington Invasive Species Council recommend that anyone who thinks their aquarium may be carrying invasive mussels to utilize the Washington Invasive app or online reporting form. It is as easy as taking a photo and submitting for an expert to review. 
    • Never release aquatic pets like goldfish or turtles into local streams or lakes.

    • Drain and clean aquariums indoors or in a location where the water cannot reach a nearby storm drain or body of water.


    Additional Resources: