The U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (State Water Board) compiled and analyzed data for mapping groundwater salinity, characterizing aquifer systems, and documenting the effects of oil-field water disposal and well integrity issues in the Midway Valley area of San Joaquin Valley, California, associated with the Midway-Sunset and Buena Vista Oil Fields. Data provided in this data release include borehole geophysical data, geochemical analyses of water samples, geological formation depths, and information on observed well log resistivity anomalies (interpreted to be from injection for disposal of produced water from oil wells or from natural causes). The data reported here were used in an accompanying interpretive manuscript describing aquifer salinity and the effects of produced water disposal in the study area. Geochemical analyses for total dissolved solids were compiled for 195 total water samples from 19 groundwater wells and 103 oil and gas wells. The data represent several decades and most originated from oil and gas producers which are archived in scanned pages in raster format on the California Geologic Energy Management Division (CalGEM) website. The data were compiled into computer readable numerical data sets for the related study. All the data and the associated manuscript are part of the State Water Board Oil and Gas Regional Monitoring Program and the associated USGS California Oil, Gas, and Groundwater (COGG) Program.
