New Zealand mudsnails found at Lake Padden

New Zealand mudsnails found at Lake Padden


City of Bellingham and Whatcom County Aquatic Invasive Species (AIS) Program staff have recently discovered invasive New Zealand mudsnails (Potamopyrgus antipodarum) in Lake Padden and are working to determine the extent of the infestation and develop a coordinated long-term response plan.

To prevent the spread of this prohibited species to other water bodies, AIS staff urge anyone coming into contact with Lake Padden to inspect and carefully clean all clothing, gear, and watercraft, prior to leaving the lake area. Clean, Drain and Dry any watercraft after use and thoroughly brush-off any debris from waders, boots, gear, and any equipment that came into contact with lake water, then rinse with clean water. Additionally, pet owners are advised to limit their pets’ exposure and clean pets thoroughly after contact with the lake.

Bellingham and Whatcom County AIS staff periodically monitor Whatcom County lakes for any evidence of new aquatic invasive species; as a result, New Zealand mudsnails were detected at Lake Padden in late August. Their identity was confirmed by the Washington Department of Fish and Wildlife (WDFW) and a taxonomic expert on Sept. 10. This is the first confirmed sighting of this aquatic invasive species in Whatcom County. According to WDFW, the first discovery in Washington state happened in 2002 in the Lower Columbia River estuary, and while the number of infested sites within the state is rising, it is still fewer than 20 areas.

New Zealand mudsnails are very small, only 4-6 millimeters, with a relatively long, narrow, spiral shell that is generally brown to almost black in color. Like other aquatic invasive species, they disrupt ecosystems by rapidly multiplying and competing with native species for space and food. This species has no known predators or parasites in Washington state that can keep populations in check and the species’ small size makes it easy for anglers, boaters, and anyone coming into contact with the water to unknowingly transport it between waterbodies. The New Zealand mudsnail’s ability to completely seal its shell allows the snail to survive out of the water for several weeks in cool, damp conditions. To date, eradication of New Zealand mudsnails once they have infested a waterbody has not been feasible in Washington; however, there are effective options to prevent their spread to uninfested lakes, streams and rivers.

“It is important that we move quickly to determine the extent of the infestation and to determine the best response options to minimize their spread to other area waterbodies,” said Teagan Ward, AIS program coordinator for the City of Bellingham. “We are working closely with the Washington Department of Fish and Wildlife and the Washington Invasive Species Councilto develop a coordinated response strategy.”  In the meantime, AIS Program staff are conducting surveys at Lake Padden and surrounding waterbodies to map the extent of the infestation. Signs have been posted by the swimming area at Lake Padden and AIS Program staff will be available to provide information to lake users.

If you suspect that you have found a New Zealand mudsnail (or any other aquatic invasive species) in another waterway, please report your information using the Washington Invasive Species Council’s WA Invasives website form or app today (Apple iOS Version | Android Version) or by calling the AIS hotline at (360) 778-7975.  When reporting an AIS sighting provide as much information as possible including close-up photos of the organism, the exact location (GPS coordinates work best), a description of what you found, and your contact information.

For more information about New Zealand mudsnails and other aquatic invasive species, visit