The New Zealand Mud Snail (NZMS; Potamopyrgus antipodarum) is native to freshwater lakes and streams in New Zealand. It is also one of a handful of freshwater mollusc invaders now found across western North America. The species was first found in the Snake River in Idaho in 1987 and is now found in many freshwater environments, including in a small section of Boulder Creek. NZMS was likey initially introduced due to freshwater fish trade, and then spread by passive transport on larger animals (eg. water fowl) and humans. The animals are both very resistant to environmental stress and parthogenetic. That is, almost all individuals are females and are able to form offspring without contributions from males (which are very rare). Therefore one snail can form a new population if it invades a new area. Without natural predators and parasites, NZMS is spreading unchecked in our native waters.