The New Zealand mud snail Potamopyrgus antipodarum (Gray, 1843) is a common invasive species in fresh and brackish water ecosystems in Europe, Australia, Japan, and North America. In some invaded habitats, P. antipodarum can reach high densities (over 500,000 snails m-2) and dominate the biomass of the benthos, leading to detrimental impacts to native biota and changes in ecosystem dynamics. We report the previously unpublished occurrence of P. antipodarum in thirteen fresh and brackish water systems adjacent to the Pacific coast of North America including a new northern range for P. antipodarum: Port Alberni, Vancouver Island, British Columbia, Canada (49.2479º, -124.8395º). We hypothesize the snail was spread from the Columbia River Estuary to Port Alberni via recreational watercraft or infected fishing equipment. Its discovery in Port Alberni reveals the potential for other aquatic nuisance species in the lower Columbia River to spread to British Columbia. Resource managers on the Pacific coast should remain vigilant and educate the public to prevent the further spread of the P. antipodarum as well as other aquatic invaders.