Compilation of lithologic data from public supply well completion reports submitted to the California Department of Water Resources (ver. 3.0 July 2025)

This data release was prepared as part of an agreement between the California Department of Water Resources (DWR) and the United States Geological Survey (USGS) to support the Sustainable Groundwater Management Act (SGMA). Of the many components of that agreement, there is a specific task requiring the Enhancement of Digital Well Completion Reports. Well-completion reports (WCRs) contain information about the wells, such as construction characteristics and lithologic data that is very valuable to SGMA. The data set presented here is a compilation of lithologic information transcribed verbatim from a subset of WCRs contained in the DWR Online System for Well Completion Reports (OSWCR). The format of the lithologic descriptions follows the DWR free form entry method, which allows for any material description to be entered into the OSWCR without standardization. The lithologic descriptions for all depth intervals recorded (in feet below land surface) by the driller on the WCR are captured verbatim, with no regularization or correction for typographical or spelling errors. Some degree of data processing may be required by a user of this dataset depending on its intended use. This data release is intended to be updated as new WCRs are transcribed over time. 
WCR lithologic data featured in version 1.0 (published March 2023) focused on 5,841 WCRs from many types of wells located primarily along the length of the California Aqueduct in the Central Valley of California. WCR lithologic data added in version 2.0 (published June 2024) were from 4,958 select public-supply wells from throughout the state that had previously been included in a compilation of WCR location and construction data made by the USGS Groundwater Ambient Monitoring and Assessment-Priority Basin Project (GAMA-PBP). WCR lithologic data added in this version 3.0 (published July 2025) are from 8,448 more public-supply wells from throughout the state. As of July 2025, approximately 57 percent of the WCRs in this dataset are also in the GAMA-PBP compilation of refined location information and construction characteristic data from WCRs primarily from water-supply wells in select locations throughout the State (Borkovich and others, 2025; https://doi.org/10.5066/P93ICKAF). Subsequent revisions planned for the GAMA-PBP data release include compiling refined location information and construction characteristic data for more WCRs with lithologic data in this data release. The GAMA-PBP data release includes a flag to indicate which WCRs also have lithologic data compiled in this data release.
All attributed values should be verified by reviewing the original WCR which can be retrieved from the California Open Data Portal WCR website (California DWR, 2025): https://data.ca.gov/dataset/well-completion-reports
California Water Code Section 13752 allows for the release of redacted copies of well completion reports to the public.
DWR is the authoritative source of these data.
Version 1.0 posted March 28, 2023
Version 2.0 posted June 12, 2024
Version 3.0 posted July 18, 2025

Tags: borehole-logging, california, california-aqueduct, central-valley, geology, lithology, usgs-632b1c93d34e71c6d67bc0bc, water-well, well-completion-report, well-construction, well-drilling, well-location
Organization: Department of the Interior