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). Geospatial data from the DOGGR were used in the prioritization analysis. Dataset include geospatial data for 222,637 petroleum wells, administrative boundaries for 514 oil, gas, and geothermal fields, and boundaries for DOGGR's 6 juristictional districts. The data were downloaded from DOGGR's Geographic Information System (GIS) Mapping website at http://www.conservation.ca.gov/dog/maps. The DOGGR GIS Mapping website is periodally updated, and the datasets downloaded by the U.S. Geological Survey in 2014 may no longer be available on the DOGGR website.