The U.S. Geological Survey collected groundwater samples from 33 wells used for domestic and small system drinking water supplies in Kern County, California in 2022. The wells were sampled for the Kern County Domestic-Supply Aquifer Study Unit of the State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater resources used for domestic and small system drinking water supplies. The study unit was defined by the extent of the Kern County subbasin of the San Joaquin Valley groundwater basin. The study unit was divided into 40 grid cells and one or two domestic or small system well were sampled in to represent 29 of the grid cells; the remaining 11 grid cells had no accessible wells. Groundwater levels were measured in 11 of 33 wells. Table 1 contains sample and site information. Groundwater samples were analyzed for field water-quality parameters, microbial indicators, volatile organic compounds, pesticides and pesticide degradants, nutrients, major ions and trace elements, hexavalent chromium, perchlorate, per- and polyfluoroalkyl substances (PFAS), stable isotopes, and groundwater age tracers. Results from these analyses are reported in Tables 2 through 8. Tables 9 and 10 report results from quality control samples. This data release contains two supplementary tables that define abbreviations (Table 11) and provide additional context for the information presented in Tables 1 through 10 (Table 12). A zipfile is included containing geospatial data (study unit boundaries, grid cell boundaries, site locations) as shapefiles.