Depths to top of perforation and base of freshwater for oil and gas production wells in California

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 California Department of Water Resources (DWR). During 2014-2016, the depth to top of perforated intervals and depth to base of freshwater for oil and gas production wells in California were extracted from well records maintained by the DOGGR. Well records including geophysical logs, well history, well completion reports, and correspondences were viewed on DOGGR's Well Finder website at https://maps.conservation.ca.gov/doggr/wellfinder/. This digital dataset contains 3,505 records for production wells, of which 2,964 wells have a recorded depth to top of perforated intervals and 1,494 wells have a recorded depth to base of freshwater. Wells were attributed with American Petroleum Institute (API) numbers, oil and gas field, and well location, well status and type, and nearest oil and gas field for wells that plotted outside field boundaries using the DOGGR All Wells geospatial data included in this data release. Wells were attributed with land surface elevations using the California National Elevation Dataset. Due to limited time and resources to analyze well records for the most recent well configuration, wells spatially distributed throughout the state and accounting for about 2 percent of the more than 185,000 production wells (new, active, idle, or plugged well status) were attributed with depth data.