There are 487 onshore oil and gas fields in California encompassing 3,392 square miles of aggregated area. The California State Water Resources Control Board (State Water Board) initiated a Regional Monitoring Program (RMP) in July 2015, intended to determine where and to what degree groundwater quality may be at potential risk to contamination related to oil and gas development activities including well stimulation, well integrity issues, produced water ponds, and underground injection. The first step in monitoring groundwater in and near oil and gas fields is to prioritize the 487 fields using consistent statewide analysis of available data that indicate potential risk of groundwater to oil and gas development. There were limited existing data on potential groundwater risk factors available for oil and gas fields across the state. During 2014-2016, the U.S. Geological Survey (USGS) extracted and compiled data from various sources, including the California Division of Oil, Gas, and Geothermal Resources (DOGGR) and the Department of Water Resources (DWR). In 2014, total well depths for groundwater wells in California were extracted from digital copies of well completion reports provided to the USGS by DWR. This digital dataset contains 16,912 well depths for domestic, municipal, irrigation, industrial, and agricultural wells that were overlying oil and gas fields or within 5 kilometers of a field boundary. Wells were attributed with approximate location, well use, and depth using information provided by DWR, and were attributed with land surface elevations using the California National Elevation Dataset. Wells were also attributed with the nearest oil and gas field using DOGGR All Wells geospatial data included in this data release.