This GIS dataset offers a link to the California portion of the Nonindigenous Aquatic Species (NAS) information resource for the United States Geological Survey. The NAS program has been established as a central repository for accurate and spatially referenced biogeographic accounts of nonindigenous aquatic species. The program provides scientic reports, online/realtime queries, spatial data sets, regional contact lists, and general information. The goal of the information system is to provide timely, reliable data about the presence and distribution of nonindigenous aquatic species. The NAS database contains locality information for more than 1100 species of vertebrates, invertebrates, and vascular plants. The NAS program provides a continual national repository of distribution information for nonindigenous aquatic species that is used to gain an understanding of aquatic introductions, identify geographic gaps, and access the status of introduced aquatic species nationwide. Data are obtained from many sources including literature, museums, databases, monitoring programs, state and federal agencies, professional communications, online reporting forms, and Aquatic Nuisance Species (ANS) hotline reports. The NAS program defines a nonindigenous aquatic species as a member(s) of a species that enters a body of water of aquatic ecosystem outside of its historic or native range. This includes not only species that arrived from outside of North America but also species native to North America that have been introduced to drainages outside their ranges within the country. Please visit http://nas.er.usgs.gov for more information and to see all of the products and data available through the NAS program.