In order to practice on-the-ground conservation, it is necessary to know the species at risk of extinction, their location, threats, habitat, etc. For the past 30 years, The Nature Conservancy and now NatureServe in collaboration with a network of natural heritage programs and conservation data centers, have worked to develop this information and inform conservation of at-risk species. NatureServe Explorer (NSE) (http://www.natureserve.org/explorer) is an acclaimed website providing authoritative conservation information for more than 50,000 plants, animals, and ecological communities in every U.S. state and Canadian province. A searchable database houses data for thousands of freshwater animal species including 88 large branchiopods, 376 crayfish, 500 odonates, 574 mayflies, 637 stoneflies, 1421 caddisflies, 380 bivalves, 757 gastropods, 800 fishes, plus various amphibians and reptiles. Information is maintained on classification, NatureServe conservation, IUCN Red List, national statuses (USESA, COSEWIC, NatureServe), and distribution. NSE represents a “snapshot” of dynamic data continually refined through input of hundreds of natural heritage scientists and collaborators. NSE is updated centrally three times annually to reflect new data from field surveys, taxonomic treatments, and conservation status assessments. Working enhancements include the addition of more detailed habitat requirements and ecological information, guidelines for assessing population viability, interactive maps, and images.