Potamopyrgus antipodarumar, New Zealand mud snails, are less than a quarter of an inch long and about half as wide, with five to six spiral turns or whorls. They can dominate river and lakebed habitat by achieving densities of more than 100,000 per square meter. They outcompete native snails and insects that are key food sources for native invertebrates and fishes. Disruption of the food chain may lead to reduced growth rates and lower populations of fish. If left alone, New Zealand mud snails can quickly become the dominant invertebrate in an aquatic system.

In November 2009, a citizen reported New Zealand mud snails in Capitol Lake, in Olympia. Within 5 days of learning about the infestation and confirming its identity, the council initiated a multi-agency, rapid response by bringing together the Washington Department of Fish and Wildlife, U.S. Fish and Wildlife Service, Washington Department of Ecology, and Washington Department of General Administration. Coordination among the agencies has been excellent. General Administration immediately closed the lake to contain the infestation, Department of Fish and Wildlife surveyed the lake, Department of Ecology developed a decontamination protocol, and the council coordinated meetings and provided outreach to the public. The council will continue to work with the partners to develop options for eradication.