The U.S. Geological Survey has published to GBIF, on behalf of Utah Division of Water Quality and the Colorado Water Quality Control Division, a freshwater mollusk survey. Although the results of the commissioned survey has an emphasis on ammonia-sensitive freshwater mussels (Superfamily Unionoidea) and non-pulmonate snails (Valvatidae, Hydrobiidae), non-native mollusks that were encountered are also included. The temporal scope of the dataset is 1871-2016 and includes historic museum and recently surveyed records.