After being recruited by local veterinarians to help find the source of a parasitic infection in southern California, we identified two species of snails, Galba cubensis and G. humilis in the Colorado River in California. We also identified that some of those snails were indeed carrying Heterobilharzia americana, the fluke that causes canine schistosomiasis. Our finding is the first report of the presence of this flatworm parasite in Southern California.