This digital dataset contains historical geochemical and other information for 481 samples of produced water (PW) from 408 sites in the Edison, Mountain View, and Ant Hill Oil Fields in Kern County, California. Produced water is a term used in the oil industry to describe water that is produced from oil wells as a byproduct along with the oil and gas. The locations from which these historical samples have been collected include 199 wells, 67 sumps, 43 storage tanks (not associated with a specific well), and 104 unidentifiable sample sources which could not be classified because of insufficient information. The wells include 176 sites identifiable by an API (American Petroleum Institute) number and 23 sites for which an API designation could not be found, but which based on the water chemistry data source, site name, sample description, or other ancillary information have been classified as wells. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval or zone produced, are available for 177 of these wells. Sites representing sumps and storage tanks were classified in a similar manner as wells based on the water chemistry data source, site name, sample description, or other ancillary information. Numerical water chemistry data were compiled from six data sources: 1) California Geologic Energy Management Division (CalGEM) Aquifer Exemptions (AE) Status webpage analytical reports (CalGEM, 2016), 2) CalGEM archived analytical reports (CalGEM, 2021), 3) CalGEM Underground Injection Control (UIC) program hard copies of laboratory analytical reports (CalGEM-UIC, 2017), 4) CalGEM's online Well Finder (WF) database of well history files (CalGEM-WF, 2022), 5) California State Water Resources Control Board GeoTracker (SWRCB-GT) online data portal analytical reports (SWRCB-GT, 2022), and 6) three California Department of Water Resources (CDWR) historical reports with water-chemistry data for samples from oil-producing zones of wells (characterized as "formation" water) and wastewater disposal sumps (CDWR/CVRWQCB-E, 1953; CDWR/CVRWQCB-M, 1956; and CDWR/CVRWQCB-A, 1957). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the laboratory analysis reports and well history files from CalGEM-WF (2022). The compiled data are divided into two separate data files described as follows: 1) a summary data file (EMA_PW_Summary_Data.xlsx) identifying each site by name, the site location, basic construction information, and American Petroleum Institute (API) number (for wells), the number of chemistry samples, period of record, sample description, and the geologic formation associated with the origin of the sampled water, or intended destination of the sample (formation into which water was to intended to be injected for samples associated with Site Type labeled as water disposal well), 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_PW_Geochemistry.xlsx) classified into one of the following groups: water-quality indicators, major and minor ions, nutrients, trace elements, naturally occurring radioactive material (NORM), volatile organic compounds (VOCs), and hydrocarbons. Ion (charge) balance calculations and percent error of these calculations were included for samples having a complete suite of major ion analyses. Analytical method, reporting level, reporting level type, dilution factor, and supplemental notes were included where available or pertinent. A data dictionary (EMA_PW_Data-Dictionary. xlsx) describes the geochemistry data file and is provided with this data release.