New Zealand Mud Snail

Divers monitoring Lake Tahoe have discovered invasive New Zealand mudsnails in areas off the South Shore, the Tahoe Regional Planning Agency (TRPA) and Tahoe Resource Conservation District (Tahoe RCD) announced today. This is the first time the species has been detected in the Tahoe Basin.

Following rapid response protocols under the federally approved Lake Tahoe Aquatic Invasive Species Management Plan, TRPA convened an incident team comprised of staff from TRPA and Tahoe RCD and partner experts. The team is rapidly deploying scientists, beginning with lake-wide dive surveys to determine the extent of the infestation and sharing all available information with state and federal wildlife managers through the Lake Tahoe Aquatic Invasive Species Coordinating Committee. Get up-to-date information on the response and potential protocols for management of the infestation on the TRPA New Zealand mudsnail page.

Recent surveys by the PFBC and partner organizations have detected New Zealand mudsnails, roughly the size of a match head, in several popular cold-water trout fisheries in central and eastern Pennsylvania. In some infested waters, New Zealand Mudsnails have the potential to reach densities of hundreds or even thousands of snails per square foot. These snails are not harmful to humans but can compete with and negatively impact native freshwater invertebrate species, such as other snails and aquatic insects.

Until recently, New Zealand Mudsnails were known to occur only in Lake Erie, Erie County; Spring Creek and Bald Eagle Creek, Centre County; and the Little Lehigh Creek in Lehigh and Berks counties. Surveys during 2020 revealed populations of snails in Trindle Spring Run, Cumberland County; Codorus Creek, York County; and Valley Creek, Chester County; prompting expanded surveys. Members of the public who observe suspected New Zealand Mudsnails or other aquatic invasive species can report sightings of aquatic invasive species to the PFBC using its online form.