This digital dataset contains historical geochemical and other information for 266 samples of groundwater (GW) from 208 wells located within 3 miles of the Edison, Mountain View, and Ant Hill Oil Fields in Kern County, California. The sampled wells include water-supply wells used primarily for domestic, irrigation, and public uses; however, the specific water-supply use of 27 wells is unknown ('unk'). Three wells with water use denoted as 'WS' (water supply) were documented as having originally been used in support of oil production, or were converted from oil production wells to water-supply wells by the time they were sampled. Numerical water chemistry data were compiled from five data sources: 1) Kern County Public Health Services Department (KCPHSD, 2017), 2) California Department of Conservation's Geologic Energy Management Division (CalGEM) archived analytical reports (CalGEM, 2021), 3) CalGEM Underground Injection Control (UIC) program hard-copy records (CalGEM-UIC, 2017), 4) CalGEM's Well Finder (WF) online database (CalGEM-WF, 2022), and 5) the California State Water Resources Control Board GeoTracker online data portal (SWRCB-GT, 2020). These data sources include varying degrees of location and well construction information. Data were manually compiled into two separate files described as follows: 1) a summary data file (EMA_GW_Summary_Data.xlsx) that includes well identifiers, location, construction, the number of chemistry samples, the period of record, specific sample dates for each site, and an inventory of which constituent groups were sampled on each date, and 2) a data file of geochemistry analyses for selected constituents (EMA_GW_Geochemistry.xlsx) classified into one of the following groups: water-quality indicators, major and minor ions, nutrients, trace elements, naturally occurring radioactive material (NORM), and volatile organic compounds (VOCs). Ion (charge) balance calculations and percent error of these calculations were included for samples having a complete suite of major ion analyses. Parameter code, analytical method, reporting level, reporting level type, dilution factor, and supplemental notes were included where available or pertinent. A data dictionary (EMA_GW_Data-Dictionary. xlsx) describes the geochemistry data file and is provided with this data release.