Potential Explanatory Variables for Groundwater Quality in California

This data release codifies and attributes values for potential explanatory factors to groundwater well locations and to groundwater basins in California. The groundwater sites are 282,000 wells that have water-quality data and are listed in the California State Water Resources Control Boards' Groundwater Ambient Monitoring and Assessment Program Groundwater Information System (GAMA GIS). The groundwater basins are 515 subbasins defined by the California Department of Water Resources. The potential explanatory factors were selected because they represent factors that may affect groundwater quality. Potential explanatory factors are attributed to groundwater sites relating to: aquifer lithology, land use (percent agricultural, urban, and natural land use), pesticide use, septic tank and underground storage densities, average number of domestic supply users, aridity index, climate (minimum and maximum temperature, and average precipitation), and distance to faults, oil and gas sites, perchlorate, and known and suspected per- and polyfluoroalkyl substances (PFAS) sources. Potential explanatory factors attributed to groundwater basins relating to: climate (minimum and maximum temperature, and average precipitation), land use (percent agricultural, urban, and natural land use), population density and number of domestic well users, septic tank and underground storage densities, and pesticide use. This data release contains a tab-delimited text file containing locations and potential explanatory factors for domestic groundwater sites (Table 1), a tab-delimited text file containing pesticide use in the 500 meter area surrounding domestic groundwater sites (Table 2), a tab-delimited text file containing distances to PFAS sources (Table 3), a tab-delimited text file containing potential explanatory factors within groundwater basins (Table 4), and a tab-delimited text file containing pesticide use within groundwater basins (Table 5).