As part of the California State Water Resources Control Board’s Oil and Gas Regional Monitoring Program , the U.S. Geological Survey collected groundwater and quality-control (QC) samples during September 2016–February 2017 from 14 water-production wells located within a one-mile buffer zone of and in the Fruitvale Oil field, Kern County, California. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds, naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon, dissolved standard and hydrocarbon gases, and dissolved noble and atmospheric gases. In total, 235 constituents and water-quality indicators were measured. Quality-control samples including replicates; source-solution, equipment, and field blanks; laboratory spikes; and split samples for inter-lab comparisons were collected at approximately 10 percent of the wells. The water well and associated quality-control sample data are presented in this data release.