The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board compiled and analyzed historical produced water chemistry data and ancillary oil well information at the Buena Vista, McKittrick, and Cymric Oil Fields in the southwestern San Joaquin Valley (SWSJV), Kern County, California. Historical water chemistry data provide information on the salt mass balance of produced water disposed of on land, and in particular, chloride which is a conservative, nonreactive tracer. Data were compiled from the California Geologic Energy Management Division (CalGEM) Underground Injection Control (UIC) scans of laboratory results for produced water samples, the CalGEM Well Finder database for oil and gas wells, and historical documents (Rogers, 1917; WZI; 1988). The SWSJV_geochem.csv dataset supplements previously compiled chemistry data by the USGS at the Midway-Sunset, Elk Hills, North Belridge, South Belridge, and Lost Hills Oil Fields (cross-referenced in this data release). The Fall1953_volumes_chemistry.csv dataset contains Fall 1953 water production volumes by lease and produced water sample results compiled from Rickett and Reaves (1954a-d) to provide a spatial understanding of historical disposal on land.

This digital dataset contains historical geochemical and other information for 271 samples of produced water from 143 sites in or near the San Ardo Oil Field in Monterey County, central 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 101 wells; three wells (DataSet_ID 118 ,125, and 130) are located outside of the administrative boundary, but closer to San Ardo (within 3 miles) than any other oil field, and therefore they were included in this dataset. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval of zone produced, are available for 97 of these wells. Additional sample sites include 11 storage tanks, and 31 unidentifiable sample sources. Designated well use and sample descriptions provide further insight about what the samples represent. The well use designation of most of the wells (79) is OG (oil/gas) and the samples (188) associated with these wells represent produced water. Samples from two wells (Dataset ID 28 and 130) are described as formation water. One well (Dataset ID 30) was drilled as a water-source well (WS) and used to supply groundwater in support of oil production at the time it was sampled, but later converted to an injection well. Another well (Dataset ID 103) was originally drilled as an oil well, but later abandoned and converted to an irrigation well prior to sampling. Eighteen wells have a site type designation of "injectate" based on the sample description combined with the designated well use at the time of sample collection (SF, steam flood; WD, water disposal; or WF, water flood). Most of the historical samples associated with injectate sites may represent water that originated from sources other than the wells at which they were collected. However, samples from two of these wells (Dataset ID 16 and 76) likely represent produced water as they were sampled prior to the wells being used for injection. Limited information is available about historical samples from storage tanks and unidentifiable sample sources, but these may represent pre- or post-treated composite samples of produced water from single or multiple wells. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file 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 (formation into which water was to intended to be injected for samples labeled as injectate) of the sample; and 2) a data file of geochemistry analyses for selected water-quality indicators, major and minor ions, nutrients, and trace elements, parameter code and (or) method, reporting level, reporting level type, and supplemental notes. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

This digital dataset contains historical geochemical and other information for 271 samples of produced water from 143 sites in or near the San Ardo Oil Field in Monterey County, central 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 101 wells; three wells (DataSet_ID 118 ,125, and 130) are located outside of the administrative boundary, but closer to San Ardo (within 3 miles) than any other oil field, and therefore they were included in this dataset. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval of zone produced, are available for 97 of these wells. Additional sample sites include 11 storage tanks, and 31 unidentifiable sample sources. Designated well use and sample descriptions provide further insight about what the samples represent. The well use designation of most of the wells (79) is OG (oil/gas) and the samples (188) associated with these wells represent produced water. Samples from two wells (Dataset ID 28 and 130) are described as formation water. One well (Dataset ID 30) was drilled as a water-source well (WS) and used to supply groundwater in support of oil production at the time it was sampled, but later converted to an injection well. Another well (Dataset ID 103) was originally drilled as an oil well, but later abandoned and converted to an irrigation well prior to sampling. Eighteen wells have a site type designation of "injectate" based on the sample description combined with the designated well use at the time of sample collection (SF, steam flood; WD, water disposal; or WF, water flood). Most of the historical samples associated with injectate sites may represent water that originated from sources other than the wells at which they were collected. However, samples from two of these wells (Dataset ID 16 and 76) likely represent produced water as they were sampled prior to the wells being used for injection. Limited information is available about historical samples from storage tanks and unidentifiable sample sources, but these may represent pre- or post-treated composite samples of produced water from single or multiple wells. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file 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 (formation into which water was to intended to be injected for samples labeled as injectate) of the sample; and 2) a data file of geochemistry analyses for selected water-quality indicators, major and minor ions, nutrients, and trace elements, parameter code and (or) method, reporting level, reporting level type, and supplemental notes. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

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.

This dataset contains geochemical and other information for 40 historical samples of produced water from the North Coles Levee Oil Field. Three of these samples are from commingled tanks containing produced water from multiple wells as noted in the “Remarks” column. Water that is produced as a byproduct of oil production is called produced water. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The data were transferred manually into a numerical dataset and organized by specific produced water chemical characteristics. Each sample is identified by its API (American Petroleum Institute) number, latitude and longitude, well name, formation name, perforation interval, and date tested. The geochemical analyses include major ions, some minor ions, total dissolved solids (TDS), pH, specific gravity, resistivity, electrical conductivity, and charge balance. The collection and analysis methods and circumstances under which the historical samples were collected cannot be fully known. The intent is to use these historical data in grouped analysis including many sample results, rather than detailed interpretation of each individual sample. Caution should be used in basing interpretations of the data on single sample results.

This digital dataset contains historical geochemical and other information for 89 samples of produced water from 84 sites in the Santa Maria Valley Oil Field in Santa Barbara 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. Additionally, 3 samples from 3 sites that represent source water used in support of oil production were included in this dataset, for a total of 92 samples and 87 sites, respectively. The locations from which these historical samples have been collected include 27 wells, 2 reservoirs, 10 storage tanks, and 49 unidentifiable sample sources. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval of zone produced, are available for 25 of the 27 wells. Designated well use and sample descriptions provide further insight about what the samples represent. The well use designation for 23 of the wells is OG (oil/gas). The 27 samples associated with these wells likely represent produced water based on well designation and history. One of the 27 samples is a composite from two wells represented by Dataset ID 46. Three wells have a site type designation of "injectate" based on the current designated well use (WD, water disposal; or WF, water flood). The samples associated with these sites are of unknown origin, but likely represent produced water from OG wells in the Santa Maria Valley Oil Field. The two reservoir samples (Dataset_ID 53 and 54) are freshwater sources that were used in support of oil production, including one reservoir (Dataset_ID 54) described as supplied by groundwater wells. Limited information is available about historical samples from storage tanks and unidentifiable sample sources. These samples may represent pre- or post-treated composite samples of produced water from single or multiple wells. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from the following sources: scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM) Underground Injection Control (UIC) program, analytical reports located within well history files in CalGEM's online Well Finder (WF) database, analytical reports available as PDFs (Portable Document Format) documents located on the State Water Resources Control Board GeoTracker (SWRCB-GT) website, and data compiled by the USGS for the National Produced Water Geochemical Database (USGS PWDB). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file 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 labeled as injectate), 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 water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), hydrocarbons, and organic acids. 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, and supplemental notes were included where available or pertinent. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

This digital dataset contains historical geochemical and other information for 89 samples of produced water from 84 sites in the Santa Maria Valley Oil Field in Santa Barbara 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. Additionally, 3 samples from 3 sites that represent source water used in support of oil production were included in this dataset, for a total of 92 samples and 87 sites, respectively. The locations from which these historical samples have been collected include 27 wells, 2 reservoirs, 10 storage tanks, and 49 unidentifiable sample sources. Well depth, perforation depths, and (or) depths referred to on geochemistry reports as interval of zone produced, are available for 25 of the 27 wells. Designated well use and sample descriptions provide further insight about what the samples represent. The well use designation for 23 of the wells is OG (oil/gas). The 27 samples associated with these wells likely represent produced water based on well designation and history. One of the 27 samples is a composite from two wells represented by Dataset ID 46. Three wells have a site type designation of "injectate" based on the current designated well use (WD, water disposal; or WF, water flood). The samples associated with these sites are of unknown origin, but likely represent produced water from OG wells in the Santa Maria Valley Oil Field. The two reservoir samples (Dataset_ID 53 and 54) are freshwater sources that were used in support of oil production, including one reservoir (Dataset_ID 54) described as supplied by groundwater wells. Limited information is available about historical samples from storage tanks and unidentifiable sample sources. These samples may represent pre- or post-treated composite samples of produced water from single or multiple wells. The numerical water chemistry data were compiled by the U.S. Geological Survey (USGS) from the following sources: scanned laboratory analysis reports available from the California Geologic Energy Management Division (CalGEM) Underground Injection Control (UIC) program, analytical reports located within well history files in CalGEM's online Well Finder (WF) database, analytical reports available as PDFs (Portable Document Format) documents located on the State Water Resources Control Board GeoTracker (SWRCB-GT) website, and data compiled by the USGS for the National Produced Water Geochemical Database (USGS PWDB). Sample site characteristics, such as well construction details, were attributed using a combination of information provided with the scanned laboratory analysis reports and well history files from CalGEM Well Finder. The compiled data are divided into two separate data files described as follows: 1) a summary data file 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 labeled as injectate), 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 water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), hydrocarbons, and organic acids. 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, and supplemental notes were included where available or pertinent. A data dictionary was created to describe the geochemistry data file and is provided with this data release.

The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board collected produced water samples from four petroleum wells in the southern San Joaquin Valley on November 5, 2014. This digital dataset contains the site information, analyzing laboratories and methods, and water chemistry and quality control results for these samples. Water chemistry results include concentrations of dissolved hydrocarbon gases and their isotopic composition; concentrations of inorganic constituents including salinity, major ions, and nutrients; dissolved organic carbon; and stable isotopes of water and strontium dissolved in water. Samples were analyzed by 5 laboratories operated or contracted by the USGS.

The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board collected produced water samples from four petroleum wells in the southern San Joaquin Valley on November 5, 2014. This digital dataset contains the site information, analyzing laboratories and methods, and water chemistry and quality control results for these samples. Water chemistry results include concentrations of dissolved hydrocarbon gases and their isotopic composition; concentrations of inorganic constituents including salinity, major ions, and nutrients; dissolved organic carbon; and stable isotopes of water and strontium dissolved in water. Samples were analyzed by 5 laboratories operated or contracted by the USGS.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater (GW) designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater and associated quality control (QC) samples in the Midway-Sunset and Buena Vista Oil Fields (MSBV) study area during March 2018 - April 2019. Groundwater samples were collected from seven irrigation, one domestic, and ten monitoring wells located within and near the administrative boundaries of the Midway-Sunset and Buena Vista Oil Fields in Kern County, California. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon (DOC), dissolved standard and hydrocarbon gases (methane through hexane), and dissolved noble and atmospheric gases. Two hundred and twenty constituents and water-quality indicators were measured; one hundred and twenty are reported here. QC samples collected as part of the Midway-Sunset and Buena Vista Oil Fields study included replicates, source-solution blanks, field blanks, and laboratory spikes.