The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board and the U.S. Bureau of Land Management compiled and analyzed data for mapping groundwater salinity and characterizing aquifer systems in and around selected oil and gas fields in California. Data were collected for the Poso Creek oil field area which includes well construction data, production and injection volumes, oil show data, digitized borehole geophysical data, geochemical analyses of produced water from oil and gas wells and water well samples, geological formation depths, core sample analyses, 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 that describes groundwater salinity and geological framework in the study area. 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, and have been compiled into computer readable numerical data sets. Other data were generated 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.