The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board compiled and analyzed data for mapping groundwater salinity and characterizing aquifer systems in and near selected oil and gas fields in California. Data for the Lost Hills, North Belridge, and South Belridge oil fields include production and injection volumes, oil show data, formation pressure data, digitized borehole geophysical data, geochemical analyses of produced water samples, geological formation depths, and geophysical data associated with estimating groundwater total dissolved solids (TDS) of formation water. All data reported here are used in an accompanying interpretive manuscript. These data have been compiled from many sources and span several decades. Some of these data have been in archived scanned pages in raster format on the California Division of Oil, Gas, and Geothermal Resources (DOGGR) website, but now have been compiled into computer readable numerical data sets. Other data were created by this project. All the data compiled and analyzed are part of the California State Water Resources Control Board’s Program of Regional Monitoring of Water Quality in Areas of Oil and Gas Production and the USGS California Oil, Gas, and Groundwater (COGG) program.

This data release Child Item contains groundwater elevation data and the associated model/code used to create groundwater elevation surfaces in and around the Lost Hills and Belridge Oil Fields. The data and model provided here are part of an interpretative manuscript by McMahon and others (2023). The data compiled and analyzed here are part of the California State Water Resources Control Board Oil and Gas Regional Monitoring Program and the U.S. Geological Survey California Oil, Gas, and Groundwater (COGG) Program.

This data release Child Item contains groundwater elevation data and the associated model/code used to create groundwater elevation surfaces in and around the Lost Hills and Belridge Oil Fields. The data and model provided here are part of an interpretative manuscript by McMahon and others (2023). The data compiled and analyzed here are part of the California State Water Resources Control Board Oil and Gas Regional Monitoring Program and the U.S. Geological Survey California Oil, Gas, and Groundwater (COGG) Program.

This dataset contains summarized historical groundwater salinity observations from wells near the Lost Hills and Belridge oil fields in the southwestern San Joaquin Valley, Kern County, California. Total dissolved solids (TDS) concentration, electrical fluid conductivity (EC), and well construction information were aggregated from public data sources and local water management agencies. Trends in total-dissolved solids (TDS) concentrations and fluid conductivity were assessed on a well-by-well basis to develop a dataset of salinity observations to support the interpretation of resistivity data derived from an airborne electromagnetic (AEM) survey flown in October 2016. Results of the trend analysis were used to identify wells that were stable with respect to three salinity categories between 2004 and 2014: fresh (TDS less than 3000 mg/L), brackish (TDS between 3,000 and 10,000 mg/L), and saline (TDS greater than 10,000 mg/L). Salinity observations considered to be contemporary with respect to the AEM survey (2015-2018) are also included in this dataset.

This dataset contains summarized historical groundwater salinity observations from wells near the Lost Hills and Belridge oil fields in the southwestern San Joaquin Valley, Kern County, California. Total dissolved solids (TDS) concentration, electrical fluid conductivity (EC), and well construction information were aggregated from public data sources and local water management agencies. Trends in total-dissolved solids (TDS) concentrations and fluid conductivity were assessed on a well-by-well basis to develop a dataset of salinity observations to support the interpretation of resistivity data derived from an airborne electromagnetic (AEM) survey flown in October 2016. Results of the trend analysis were used to identify wells that were stable with respect to three salinity categories between 2004 and 2014: fresh (TDS less than 3000 mg/L), brackish (TDS between 3,000 and 10,000 mg/L), and saline (TDS greater than 10,000 mg/L). Salinity observations considered to be contemporary with respect to the AEM survey (2015-2018) are also included in this dataset.

The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board compiled and analyzed data for the purpose of mapping groundwater salinity in selected oil and gas fields in California. The data for the Rosedale Ranch oil field include well construction data, digitized borehole geophysical data, geochemical analyses of water samples from oil and gas wells and groundwater wells, geological formation depths, and the groundwater total dissolved solids (TDS) calculations used in the accompanying manuscript. These data have been compiled from many sources and span several decades. The well construction data includes attributes such as the date drilling began (spud date), well depth, the depth of top producing perforation, and borehole orientation. These data have been in archived scanned pages in raster format on the Division of Oil, Gas, and Geothermal Resources (DOGGR) website. Similarly, the borehole geophysical data, measured by oil companies, have been archived in raster format. This project has converted the borehole geophysical data from selected oil and gas wells into a computer readable numerical format. The geochemical analyses have also been archived in scanned formats, but are now compiled and verified for analysis. All of the data collected are part of the California State Water Resources Control Board's Program of Regional Monitoring of Water Quality in Areas of Oil and Gas Production and the USGS California Oil, Gas, and Groundwater (COGG) program.

The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board compiled and analyzed data for the purpose of mapping groundwater salinity in selected oil and gas fields in California. The data for the Rosedale Ranch oil field include well construction data, digitized borehole geophysical data, geochemical analyses of water samples from oil and gas wells and groundwater wells, geological formation depths, and the groundwater total dissolved solids (TDS) calculations used in the accompanying manuscript. These data have been compiled from many sources and span several decades. The well construction data includes attributes such as the date drilling began (spud date), well depth, the depth of top producing perforation, and borehole orientation. These data have been in archived scanned pages in raster format on the Division of Oil, Gas, and Geothermal Resources (DOGGR) website. Similarly, the borehole geophysical data, measured by oil companies, have been archived in raster format. This project has converted the borehole geophysical data from selected oil and gas wells into a computer readable numerical format. The geochemical analyses have also been archived in scanned formats, but are now compiled and verified for analysis. All of the data collected are part of the California State Water Resources Control Board's Program of Regional Monitoring of Water Quality in Areas of Oil and Gas Production and the USGS California Oil, Gas, and Groundwater (COGG) program.

The U.S. Geological Survey (USGS) and California State University-Sacramento, in cooperation with the California State Water Resources Control Board and U.S. Bureau of Land Management, compiled and analyzed data for mapping groundwater salinity in selected oil and gas fields in California. The data for the Midway-Sunset (MWSS) oil field includes digitized borehole geophysical data, geochemical analyses of produced water samples from oil and gas wells, core sample analysis from select wells, and groundwater total dissolved solids (TDS) estimations with the related geophysical log data. These data have been compiled from many sources and span several decades. The geochemical data include ion concentrations and TDS which are attributed with the sample date, geological formation, and perforation depths. These data have been in archived scanned pages of historical lab analyses on the Division of Oil, Gas, and Geothermal Resources (DOGGR) website. The borehole geophysical data has been provided by California Division of Oil, Gas, and Geothermal Resources (DOGGR). These data were compiled primarily to create groundwater salinity maps to assist in regional groundwater monitoring as part of the California State Water Resources Control Board's Program of Regional Monitoring of Water Quality in Areas of Oil and Gas Production and the USGS California Oil, Gas, and Groundwater (COGG) program.

The U.S. Geological Survey (USGS) and California State University-Sacramento, in cooperation with the California State Water Resources Control Board and U.S. Bureau of Land Management, compiled and analyzed data for mapping groundwater salinity in selected oil and gas fields in California. The data for the Midway-Sunset (MWSS) oil field includes digitized borehole geophysical data, geochemical analyses of produced water samples from oil and gas wells, core sample analysis from select wells, and groundwater total dissolved solids (TDS) estimations with the related geophysical log data. These data have been compiled from many sources and span several decades. The geochemical data include ion concentrations and TDS which are attributed with the sample date, geological formation, and perforation depths. These data have been in archived scanned pages of historical lab analyses on the Division of Oil, Gas, and Geothermal Resources (DOGGR) website. The borehole geophysical data has been provided by California Division of Oil, Gas, and Geothermal Resources (DOGGR). These data were compiled primarily to create groundwater salinity maps to assist in regional groundwater monitoring as part of the California State Water Resources Control Board's Program of Regional Monitoring of Water Quality in Areas of Oil and Gas Production and the USGS California Oil, Gas, and Groundwater (COGG) program.

An investigation was done by the U.S. Geological Survey, in cooperation with the California State Water Resources Control Board's Program of Regional Groundwater Monitoring of Water Quality in Areas of Oil and Gas Production, to assess the effects of oil and gas production activities on nearby groundwater resources. During November 2016–September 2017, 30 samples were collected at groundwater wells and 1 sample was collected at a surface-water site. This dataset contains site information and water chemistry results for samples collected near the Lost Hills and North and South Belridge oil fields, 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, low molecular weight organic acids, dissolved standard and hydrocarbon gases, and dissolved noble and atmospheric gases. Quality-control samples including replicates; source-solution, equipment, and field blanks; laboratory spikes; and split samples for interlab comparisons were collected and summarized in this data release.