This data release is a compilation of construction depth information for 12,383 active and inactive public-supply wells (PSWs) in California from various data sources. Construction data from multiple sources were indexed by the California State Water Resources Control Board Division of Drinking Water (DDW) primary station code (PS Code). Five different data sources were compared with the following priority order: 1, Local sources from select municipalities and water purveyors (Local); 2, Local DDW district data (DDW); 3, The United States Geological Survey (USGS) National Water Information System (NWIS); 4, The California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment Groundwater Information System (SWRCB); and 5, USGS attribution of California Department of Water Resources well completion report data (WCR). For all data sources, the uppermost depth to the well's open or perforated interval was attributed as depth to top of perforations (ToP). The composite depth to bottom of well (Composite BOT) field was attributed from available construction data in the following priority order: 1, Depth to bottom of perforations (BoP); 2, Depth of completed well (Well Depth); 3; Borehole depth (Hole Depth). PSW ToPs and Composite BOTs from each of the five data sources were then compared and summary construction depths for both fields were selected for wells with multiple data sources according to the data-source priority order listed above. Case-by-case modifications to the final selected summary construction depths were made after priority order-based selection to ensure internal logical consistency (for example, ToP must not exceed Composite BOT). This data release contains eight tab-delimited text files. WellConstructionSourceData_Local.txt contains well construction-depth data, Composite BOT data-source attribution, and local agency data-source attribution for the Local data. WellConstructionSourceData_DDW.txt contains well construction-depth data and Composite BOT data-source attribution for the DDW data. WellConstructionSourceData_NWIS.txt contains well construction-depth data, Composite BOT data-source attribution, and USGS site identifiers for the NWIS data. WellConstructionSourceData_SWRCB.txt contains well construction-depth data and Composite BOT data-source attribution for the SWRCB data. WellConstructionSourceData_WCR.txt contains contains well construction depth data and Composite BOT data-source attribution for the WCR data. WellConstructionCompilation_ToP.txt contains all ToP data listed by data source. WellConstructionCompilation_BOT.txt contains all Composite BOT data listed by data source. WellConstructionCompilation_Summary.txt contains summary ToP and Composite BOT values for each well with data-source attribution for both construction fields. All construction depths are in units of feet below land surface and are reported to the nearest foot.

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

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

Well construction data for 11,917 domestic and 2,390 public-supply wells in the Central Valley were compiled as part of the U.S. Geological Survey (USGS) National Water Quality Assessment Project (NAWQA) and California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP). Data were compiled for wells reported in the USGS National Water Information System (NWIS) database and from well information reported to the SWRCB Department of Drinking Water (SWRCB-DDW). Driller’s log data were transcribed from scanned images of well completion reports filed with California Department of Water Resources (DWR). The wells reported in this data release were filtered by water use to select domestic and public-supply wells and omit other water uses. The compilation was then assumed to be representative of the total population of domestic and public-supply wells in the Central Valley. The wells in the compilation were constructed between 1911 and 2008 but are not grouped or separated by date. The data were used to produce two point data sets containing well location and construction information (depth from land surface to the top and bottom of the well screen, hereafter well-screen tops and bottoms; and screen length), and 12 interpolated GIS raster surfaces created by using Empirical Bayesian Kriging on a 1600 by 1600 meter (1 square-mile) grid. The tables are also included in csv format. The 12 rasters comprise predicted values for well screen tops and bottoms and their 10th and 90th quantile values. The interpolated surfaces may also be used to calculate volumes of water-supply in the Central Valley defined by the well-screen tops and bottoms.

Well construction data for 11,917 domestic and 2,390 public-supply wells in the Central Valley were compiled as part of the U.S. Geological Survey (USGS) National Water Quality Assessment Project (NAWQA) and California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP). Data were compiled for wells reported in the USGS National Water Information System (NWIS) database and from well information reported to the SWRCB Department of Drinking Water (SWRCB-DDW). Driller’s log data were transcribed from scanned images of well completion reports filed with California Department of Water Resources (DWR). The wells reported in this data release were filtered by water use to select domestic and public-supply wells and omit other water uses. The compilation was then assumed to be representative of the total population of domestic and public-supply wells in the Central Valley. The wells in the compilation were constructed between 1911 and 2008 but are not grouped or separated by date. The data were used to produce two point data sets containing well location and construction information (depth from land surface to the top and bottom of the well screen, hereafter well-screen tops and bottoms; and screen length), and 12 interpolated GIS raster surfaces created by using Empirical Bayesian Kriging on a 1600 by 1600 meter (1 square-mile) grid. The tables are also included in csv format. The 12 rasters comprise predicted values for well screen tops and bottoms and their 10th and 90th quantile values. The interpolated surfaces may also be used to calculate volumes of water-supply in the Central Valley defined by the well-screen tops and bottoms.

This Well Completion Report geospatial dataset represents an index to a subset of records available from the California Department of Water Resources' (DWR) Online System for Well Completion Reports (OSWCR). This release contains water supply well records from Amador, Calaveras, El Dorado, Nevada, Placer, Sacramento, San Bernardino, Sutter, and Yuba counties. The USGS California Water Science Center GAMA project has provided additional attributes: top of open interval; number of open intervals; and various other identifiers such as public supply well number and USGS site number where they can be identified. In some cases, locations are georeferenced to finer resolution based on county APN or 911 geospatial datasets. The attributed information is linked to the redacted publicly available image when the link can be resolved. This dataset is for information purposes only. All attribute values should be verified by reviewing the original Well Completion Report. 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. https://data.ca.gov/dataset/well-completion-reports

This Well Completion Report geospatial dataset represents an index to a subset of records available from the California Department of Water Resources' (DWR) Online System for Well Completion Reports (OSWCR). This release contains water supply well records from Amador, Calaveras, El Dorado, Nevada, Placer, Sacramento, San Bernardino, Sutter, and Yuba counties. The USGS California Water Science Center GAMA project has provided additional attributes: top of open interval; number of open intervals; and various other identifiers such as public supply well number and USGS site number where they can be identified. In some cases, locations are georeferenced to finer resolution based on county APN or 911 geospatial datasets. The attributed information is linked to the redacted publicly available image when the link can be resolved. This dataset is for information purposes only. All attribute values should be verified by reviewing the original Well Completion Report. 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. https://data.ca.gov/dataset/well-completion-reports

This Well Completion Report geospatial dataset represents an index to a subset of records available from the California Department of Water Resources' (DWR) Online System for Well Completion Reports (OSWCR). This version of the release contains data from 297,162 well completion reports (WCRs) for water supply wells from all counties in California. A subset of WCRs for 5,350 wells that are not water supply wells also are included. The California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) did studies of water quality in groundwater resources used by domestic wells in parts of those counties in 2012-2024, and these data were compiled as part of those studies. A total of 9,538 WCRs have been added in this update. This dataset differs from the data provided in OSWCR because it includes data for some additional fields such as NumberOpenIntervals, USGS_SiteNumber, and SWRCB_DDW_PublicSupplyWell and doesn't include some fields that are in OSWCR. Some data attributed in OSWCR were checked for accuracy and updated, and more precise locations were determined for some wells. The additional fields provide more detail about the open or perforated intervals in the well, various identification numbers for the wells, and generalized lithology, and were populated where they could be identified. Some attributes have been provided by cooperating entities as indicated in the REFERENCE field. About 60 percent of the locations are georeferenced to finer resolution based on county Assessor's Parcel Number (APN), 911, or local water authority geospatial datasets. The attributed information is linked to the redacted publicly available Department of Water Resources well completion report image when the link can be resolved. This dataset is for information purposes only. All attribute values should be verified by reviewing the original Well Completion Report. 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. https://data.ca.gov/dataset/well-completion-reports Version History Summary: Version 1.0 posted online August 8, 2019 (available upon request) Version 2.0 posted online January 24, 2023 (https://doi.org/10.5066/P9R1V41Q) Version 3.0 posted online July 21, 2023 (available upon request) Version 4.0 posted online September 30, 2024 Version 5.0 posted online June 05, 2025 Version 6.0 posted online December 30, 2025

This Well Completion Report geospatial dataset represents an index to a subset of records available from the California Department of Water Resources' (DWR) Online System for Well Completion Reports (OSWCR). This version of the release contains data from 292,976 well completion reports (WCRs) for water supply wells from Amador, Butte, Calaveras, Colusa, Contra Costa, El Dorado, Fresno, Glenn, Kern, Kings, Madera, Mariposa, Merced, Monterey, Nevada, Placer, Riverside, Sacramento, San Benito, San Bernardino, San Luis Obispo, San Joaquin, Santa Clara, Santa Cruz, Shasta, Solano, Stanislaus, Sutter, Tehama, Tulare, Tuolumne, Yolo, and Yuba counties in California. A subset of WCRs for 5969 wells that are not water supply wells also are included. The California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) did studies of water quality in groundwater resources used by domestic wells in parts of those counties in 2012-2023, and these data were compiled as part of those studies. Ninety-two WCRs from the additional California counties of Trinity, Ventura, Alameda, San Diego, Sierra, Orange, Lassen, Sonoma, Inyo, and Los Angeles have been included because the WCRs were initially incorrectly assigned to one county and are now reported with their correct county assignment. This dataset differs from the data provided in OSWCR because it includes data for some additional fields such as NumberOpenIntervals, USGS_SiteNumber, and SWRCB_DDW_PublicSupplyWell and doesn't include some fields that are in OSWCR, some data attributed in OSWCR were checked for accuracy and updated, and more precise locations were determined for some wells. The additional fields provide more detail about the open or perforated intervals in the well, various identification numbers for the wells, and generalized lithology, and were populated where they could be identified. Some attributes have been provided by cooperating entities as indicated in the REFERENCE field. About 60 percent of the locations are georeferenced to finer resolution based on county Assessor's Parcel Number (APN), 911, or local water authority geospatial datasets. The attributed information is linked to the redacted publicly available Department of Water Resources well completion report image when the link can be resolved. This dataset is for information purposes only. All attribute values should be verified by reviewing the original Well Completion Report. 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. https://data.ca.gov/dataset/well-completion-reports Version History Summary: Version 1.0 posted online August 8, 2019 (available upon request) Version 2.0 posted online January 24, 2023 (https://doi.org/10.5066/P9R1V41Q) Version 3.0 posted online July 21, 2023 (available upon request) Version 4.0 posted online September 30, 2024 Version 5.0 posted online June 04, 2025

This Well Completion Report geospatial dataset represents an index to a subset of records available from the California Department of Water Resources' (DWR) Online System for Well Completion Reports (OSWCR). This version of the release contains data from 262,649 well completion reports (WCRs) for water supply wells from Amador, Butte, Calaveras, Colusa, El Dorado, Glenn, Kern, Kings, Merced, Monterey, Nevada, Placer, Riverside, Sacramento, San Benito, San Bernardino, San Luis Obispo, San Joaquin, Santa Clara, Santa Cruz, Shasta, Stanislaus, Sutter, Tehama, Tulare, and Yuba counties in California. A subset of WCRs for 5969 wells that are not water supply wells also are included. The California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) did studies of water quality in groundwater resources used by domestic wells in parts of those counties in 2012-2023, and these data were compiled as part of those studies. Ninety-two WCRs from the additional California counties of Trinity, Ventura, Alameda, San Diego, Sierra, Orange, Lassen, Sonoma, Inyo, Tuolumne, Mariposa, Los Angeles, Fresno, and Madera have been included because the WCRs were initially incorrectly assigned to one county and are now reported with their correct county assignment. This dataset differs from the data provided in OSWCR because it includes data for some additional fields such as NumberOpenIntervals, USGS_SiteNumber, and SWRCB_DDW_PublicSupplyWell and doesn't include some fields that are in OSWCR, some data attributed in OSWCR were checked for accuracy and updated, and more precise locations were determined for some wells. The additional fields provide more detail about the open or perforated intervals in the well, various identification numbers for the wells, and generalized lithology, and were populated where they could be identified. Some attributes have been provided by cooperating entities as indicated in the REFERENCE field. About 60 percent of the locations are georeferenced to finer resolution based on county Assessor's Parcel Number (APN), 911, or local water authority geospatial datasets. The attributed information is linked to the redacted publicly available Department of Water Resources well completion report image when the link can be resolved. This dataset is for information purposes only. All attribute values should be verified by reviewing the original Well Completion Report. 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. https://data.ca.gov/dataset/well-completion-reports Version History Summary: Version 1.0 posted online August 8, 2019 (available upon request) Version 2.0 posted online January 24, 2023 (https://doi.org/10.5066/P9R1V41Q) Version 3.0 posted online July 21, 2023 (available upon request) Version 4.0 posted online September 24, 2024