In conjunction with the release of California’s Groundwater Update 2020, DWR has compiled a comprehensive list of the official basin boundary descriptions for all of California’s 515 groundwater basins. These descriptions were originally developed by DWR as part of California’s Groundwater (B-118) Update 2003 and have since been updated for some groundwater basins as a result of the 2016 and 2018 Basin Boundary Modifications. To make locating descriptions easier, they have been organized by region which is determined by the first number of the basin number (i.e. 1-XXX).

The original basin descriptions developed for California’s Groundwater (B-118) Update 2003 also included summaries of the hydrologic and hydrogeologic setting, groundwater storage capacity and water budget, groundwater level and quality trends, well yields, basin management, and references. This additional information contained in the basin descriptions will now be referred to as “basin reports” and are still available online as part of the Bulletin 118 - Update 2003 report.

The dataset is a feature class showing the boundaries of 515 groundwater basins and subbasins as defined by the California Department of Water Resources as last modified by the Basin Boundary Emergency Regulation adopted on October 21, 2015 and subsequent modifications requested through the Basin Boundary Modification Request Process. This data is current as of December 9, 2022. The file is in ESRI geodatabase format and is intended for use with compatible GIS software. Groundwater basins are represented as polygon features and designated on the basis of geological and hydrological conditions - usually the occurrence of alluvial or unconsolidated deposits. When practical, large basins are also subdivided by political boundaries, as in the Central Valley. Basins are named and numbered per the convention of the Department of Water Resources.

Ten hydrogeologic provinces of California are represented by a region- class feature called "provinces" within this digital data set. These provinces were identified and defined in the USGS Water Resource Investigation Report (WRIR) 03-4166 (Belitz and others, 2003) titled, "Framework for a Ground-water Quality Monitoring and Assessment Plan for California". Hydrogeologic provinces are generalized areas where hydrology and/or geology have similar characteristics. The Southern Cal Islands group was not previously defined as a province in WRIR 03-4166, and is therefore identified as a group in this dataset.

These provinces were created by grouping polygons from two formally created digital data sets into respective provinces. New polygons were created where necessary. The two digital data set sources consisted of watershed polygons (calwater) and groundwater basin polygons (gw_basins) compiled to create an original publication of hydrogeologic province boundaries in the form of ...

Bulletin 118 defines the recognized groundwater basins and subbasins throughout the State of California. The Bulletin 118 document provides information on these basins/subbasins and the nature and extent of groundwater occurrence and management within the State. The Bulletin 118 dataset makes the geographic locations and extent of the 517 basins/subbasins publically available, for use in external mapping/GIS applications.

California’s Groundwater (Bulletin 118) is the State’s official publication on the occurrence and nature of groundwater in California. The latest version of the report, California's Groundwater - Update 2020 was publicly released on November 16, 2021. The publication defines the boundaries and describes the hydrologic characteristics of California’s groundwater basins. California’s Groundwater also provides information on groundwater management and recommendations for the future.

With the passage of the Sustainable Groundwater Management Act in 2014, California’s Groundwater now serves an additional role by providing Groundwater Sustainability Agencies with three critical pieces of information regarding groundwater basins: Critical Conditions of Overdraft, Basin Boundaries, and Basin Priority. Updates to California’s Groundwater will be released every five years starting in 2020.

This dataset includes the latest update, historical publications and supporting documents for California's Groundwater

This dataset includes the official groundwater basin boundary descriptions for California's 515 groundwater basins. To make locating descriptions easier, they have been organized by region. This resource contains descriptions for basins that start with the number one (1-XXX) indicating they are located in the North Coast Region

This dataset includes the official groundwater basin boundary descriptions for California's 515 groundwater basins. To make locating descriptions easier, they have been organized by region. This resource contains descriptions for basins that start with the number eight (4-XXX) indicating they are located in the South Coast Region.

The following data and resources were used for the SGMA Basin Prioritization of California’s 515 groundwater basins and subbasins. The Department of Water Resources is mandated by California Water Code Section 10933(b) to prioritize each basin based on eight components. For more information about how the data was analyzed for Basin Prioritization please see Sustainable Groundwater Management Act Basin Prioritization - Process and Results Document. Additional questions or requests for information related any of the Basin Prioritization datasets should be directed to the Sustainable Groundwater Management Office at sgmps@water.ca.gov. For more information on SGMA Basin Prioritization please visit the SGMA Basin Prioritization Homepage.

Geospatial data about California Groundwater Basins. Export to CAD, GIS, PDF, CSV and access via API.

The dataset is a feature class showing the boundaries of 515 groundwater basins and subbasins as defined by the California Department of Water Resources as last modified by the Basin Boundary Emergency Regulation adopted on October 21, 2015 and subsequent modifications requested through the Basin Boundary Modification Request Process. Groundwater basins are represented as polygon features and designated on the basis of geological and hydrological conditions - usually the occurrence of alluvial or unconsolidated deposits. When practical, large basins are also subdivided by political boundaries, as in the Central Valley. Basins are named and numbered per the convention of the Department of Water Resources. The associated data are considered DWR enterprise GIS data, which meet all appropriate requirements of the DWR GIS Spatial Data Standards. DWR makes no warranties or guarantees, either expressed or implied, as to the completeness, accuracy or correctness of the data, nor accepts or assumes any liability arising from or for any incorrect, incomplete or misleading subject data. The official DWR GIS Data Steward for this dataset is Brett Wyckoff, who may be contacted at 916-651-9283, or at brett.wyckoff@water.ca.gov. Comments, problems, improvements, updates, or suggestions should be forwarded to the official GIS Data Steward as available and appropriate.

This data was acquired from the Integrated Water Resources Information System (IWRIS), hosted by the California Department of Water Resources (DWR). The Bulletin 118 Groundwater Basins shapefile was downloaded, projected to the CCS83 Zone 5 (ftUS) Map projection and clipped to the Los Angeles County Boundary for internal Los Angeles County use. Please also visit information on Bulletin 118.Supplemental Information:Stormwater Engineering, a Division of the Los Angeles County Department of Public Works, maintains a list of its spreading grounds.The California Department of Water Resources has information on statewide issues.The California Geoportal offers statewide GIS data.

This data release contains monthly 270-meter gridded Basin Characterization Model (BCMv8) climate inputs and hydrologic outputs for 17 California Coastal Basins (Eel River, Fort Bragg, Fort Ross, Klamath, Los Angeles, Mad River, Mattole, Napa Sonoma, Russian River, Salinas, San Diego, San Francisco Coastal South, Santa Clara River Valley, Santa Clara River Valley South Bay, Smith, South Bay, and South Delta) and the surrounding contributing watershed area containing 181 groundwater basins. Downscaled gridded climate inputs (Daly et al., 2008) include: precipitation (ppt), minimum temperature (tmn), maximum temperature (tmx), and potential evapotranspiration (pet). Gridded hydrologic variables include: actual evapotranspiration (aet), climatic water deficit (cwd), snowpack (pck), recharge (rch), runoff (run), and soil storage (str). The units for temperature variables are degrees Celsius, and all other variables are in millimeters. Monthly historical variables from water years 1896 to 2019 are summarized into water year files and long-term average summaries for water years 1981-2010. Four future climate scenarios were spatially downscaled from 6 kilometers to 270 meters, and run through the BCMv8 using the same model parameters. The future climate scenarios (Pierce et al., 2014) are all Representative Concentration Pathway (RCP) 8.5 and include: CanESM2, CNRM-CM5, HadGEM2-ES, and MIROC5 from California's Forth Climate Change Assessment. Future climate scenarios span from water year 2007 to 2099, and monthly variables were summarized by water year and the average 2070 to 2099 period. Streamflow for each calibration gage was calculated using a post processing Excel spreadsheet and BCMv8 recharge and runoff, and are provided in tabular comma separated .csv files. Raster grids are in the NAD83 California Teale Albers, (meters) projection in an open format ascii text file (.asc). References cited: Daly, C., Halbleib, M., Smith, J.I., Gibson, W.P., Doggett, M.K., Taylor, G.H., Curtis, J. and Pasteris, P.P., 2008. Physiographically sensitive mapping of climatological temperature and precipitation across the conterminous United States. International Journal of Climatology: a Journal of the Royal Meteorological Society, 28(15), pp.2031-2064. Flint, L.E., Flint, A.L., and Stern, M.A., 2021, The Basin Characterization Model - A monthly regional water balance software package (BCMv8) data release and model archive for hydrologic California (ver. 2.0, February 2023): U.S. Geological Survey data release, https://doi.org/10.5066/P9PT36UI. Pierce, D.W., Cayan, D.R. and Thrasher, B.L., 2014. Statistical downscaling using localized constructed analogs (LOCA). Journal of hydrometeorology, 15(6), pp.2558-2585.

The polygon shapefile contains the boundaries of 515 groundwater basins and subbasins as defined by the California Department of Water Resources (Bulletin 118, 2003). Groundwater basins are represented as polygon features and designated on the basis of geological and hydrological conditions - usually the occurrence of alluvial or unconsolidated deposits. When practical, large basins are also subdivided by political boundaries, as in the Central Valley. Basins are named and numbered per the convention of the Department of Water Resources. The associated data are considered DWR enterprise GIS data, which meet all appropriate requirements of the DWR GIS Spatial Data Standards. DWR makes no warranties or guarantees, either expressed or implied, as to the completeness, accuracy or correctness of the data, nor accepts or assumes any liability arising from or for any incorrect, incomplete or misleading subject data.

In conjunction with the release of California’s Groundwater Update 2020, DWR has compiled a comprehensive list of the official basin boundary descriptions for all of California’s 515 groundwater basins. These descriptions were originally developed by DWR as part of California’s Groundwater (B-118) Update 2003 and have since been updated for some groundwater basins as a result of the 2016 and 2018 Basin Boundary Modifications. To make locating descriptions easier, they have been organized by region which is determined by the first number of the basin number (i.e. 1-XXX). The original basin descriptions developed for California’s Groundwater (B-118) Update 2003 also included summaries of the hydrologic and hydrogeologic setting, groundwater storage capacity and water budget, groundwater level and quality trends, well yields, basin management, and references. This additional information contained in the basin descriptions will now be referred to as “basin reports” and are still available online as part of the Bulletin 118 - Update 2003 report.

The California Air Basins layer is a polygon shapefile coverage representing the 15 California air basins, as defined in state statute and regulation. See the California Health and Safety Code, Section 39606 et seq. and California Code of Regulations, Title 17, Section 60100 et seq. Shapefile coverage. This data layer shows the air basin boundaries and their names, as of October 2014. The file has been updated using as main source the: California Environmental Protection Agency Air Resources Board maps (http://www.arb.ca.gov/knowzone/basin/basin.htm)

The California State Water Resources Control Board is currently in the process of improving the functionality and accessibility of information residing in their Water Quality Control Plans (aka Basin Plans). In order to achieve this, the data (i.e. statewide water quality objectives, beneficial uses, applicable TMDLs, etc.), are being transferred to a standardized digital format and linked to applicable surface water features. This dataset is limited to the beneficial uses data, while the water quality objectives, applicable TMDLs, etc. will be released at a later date. Data formats will include GIS data layers and numerous nonspatial data tables. The GIS layers contain hydrography features derived from a 2012 snapshot of the high-resolution (1:24000 scale) National Hydrography Dataset with added attribution. Nonspatial tables will contain various textual and numeric data from the Regional Basin and State Plans. The extent of the dataset covers the state of California and the non-spatial tables reflect the information and elements from the various plans used up to 2020. The GIS layers and associated attribution will enable the future integration of the various elements of the Basin Plans to ensure that all applicable Basin Plan requirements for a particular waterbody can be determined in a quick and precise manner across different modern mediums. The data are being managed and the project implemented by State and Regional Water Board staff using ESRI's ArcGIS Server and ArcSDE technology.The statewide layer is only provided as a map image layer service. The data is available as feature layer services by Regional Board extract. To view all regional board feature layer extracts go to the Basin Plan GIS Data Library Group here.

The California Groundwater Units dataset classifies and delineates the State into one of three groundwater based polygon units: (1) those areas defined as alluvial groundwater basins or sub-basins (DWR, 2002), (2) highland areas that are adjacent to and topographically upgradient of groundwater basins, and (3) highland areas not associated with any groundwater basin. In total, 938 Groundwater Units are represented. The Groundwater Unit dataset relates existing groundwater basins with their newly delineated highland areas which can be used in subsequent hydrologic studies. The method used to delineate highland areas is similar to methods used to delineate a contributing area, the difference being that highland areas are constrained to the immediately surrounding upslope (upsteam) area.

Highland areas were delineated based upon the surficial contributing area (watershed) immediately adjacent to each groundwater basin. The method of delineation is comparable to the me ...

DWR has a long history of studying and characterizing California’s groundwater aquifers as a part of California’s Groundwater (Bulletin 118). The Basin Characterization Program provides the latest data and information about California’s groundwater basins to help local communities better understand their aquifer systems and support local and statewide groundwater management.

Under the Basin Characterization Program, new and existing data (AEM, lithology logs, geophysical logs, etc.) will be integrated to create continuous maps and three-dimensional models. To support this effort, new data analysis tools will be developed to create texture models, hydrostratigraphic models, and aquifer flow parameters. Data collection efforts will be expanded to include advanced geologic, hydrogeologic, and geophysical data collection and data digitization and quality control efforts will continue. To continue to support data access and data equity, the Basin Characterization Program will develop new online, GIS-based, visualization tools to serve as a central hub for accessing and exploring groundwater related data in California.

Additional information can be found on the Basin Characterization Program webpage.

DWR's Evaluation of Groundwater Resources: Maps and Models

DWR will undertake local, regional, and statewide investigations to evaluate California's groundwater resources and develop state-stewarded maps and models. New and existing data will be combined and integrated using the analysis tools described below to develop maps and models to be developed will describe the grain size, the hydrostratigraphic properties, and hydrogeologic conceptual properties of California’s aquifers. These maps and models help groundwater managers understand how groundwater is stored and moves within the aquifer. The models will be state-stewarded, meaning that they will be regularly updated, as new data becomes available, to ensure that up-to-date information is used for groundwater management activities. The first iterations of the following maps and models will be published as they are developed:

• Texture Models
• Hydrostratigraphic Models
• Aquifer Recharge Potential Maps
• Extent of Important Aquifer Units
• Depth to Basement
• Depth to Freshwater

Data Collection

As a part of the Basin Characterization Program, advanced geologic, hydrogeologic, and geophysical data will be collected to improve our understanding of groundwater basins. Data collected under Basin Characterization are collected at a local, regional, or statewide scale depending on the scope of the study.

Local Investigations:

• Madera & North Kings
• Pajaro
• Western San Joaquin Valley

Regional Investigations:

• Sacramento Valley
• Four County Area of San Joaquin Valley (Madera, Fresno, Kings, and Tulare)
• San Joaquin Valley

Statewide Investigations:

• Statewide AEM Surveys

Data Compilation and Digitization

Digitized Existing Lithology and Geophysical Logs

Lithology and geophysical logging data have been digitized to support the Statewide AEM Survey Project and will continue to be digitized to support Basin Characterization efforts. All digitized lithology logs with Well Completion Report IDs will be imported back into the OSWCR database.

Digitized lithology and geophysical logging can be found under the following resource:

• Digitized Lithology and Geophysical Logs.

Analysis Tools and Process Documents

To develop the state-stewarded maps and models outlined above, new tools and process documents will be created to integrate and analyze a wide range of data, including geologic, geophysical, and hydrogeologic information. By combining and assessing various datasets, these tools will help create a more complete picture of California's groundwater basins. All tools, along with guidance documents, will be made publicly available for local groundwater managers to use to support development of maps and models at a local scale. All tools and guidance will be updated as revisions to tools and process documents are made.

Analysis tools and process documents can be found under the following resource:

• Data Analysis Tools and Process Documents.

Data Visualization

Data access equity is a priority for the Basin Characterization Program. To ensure data access equity, the Basin Characterization Program has developed applications and tools to allow data to be visualized without needing access to expensive data visualization software. This list below provides links and descriptions for the Basin Characterization's suite of data viewers.

SGMA Data Viewer: Basin Characterization tab: Provides maps, depth slices, and profiles of Basin Characterization maps, models, and datasets, including the following:

• Aquifer Recharge Potential Maps
• Subsurface Texture Model Depth Slices
• Statewide AEM Survey Texture Depth Slices
• Lithology Log Location Maps
• Geophysical Logs Location Maps
• Statewide AEM Survey Profile Images

3D AEM Data Viewer: Displays the Statewide AEM Survey electrical resistivity and coarse fraction data, along with lithology logs, in a three-dimensional space.

DWR's Subsurface Viewer: Provides a map view and profile view of the Statewide AEM Survey electrical resistivity and coarse fraction data, along with lithology logs. The map view dynamically shows the exact location of AEM data displayed.

Basin Characterization Exchange

The Basin Characterization Exchange (BCX) is a meeting series and network space for the Basin Characterization community to exchange ideas, share lessons learned, define needed guidance, and highlight research topics. The BCX is open to federal, state, and local agencies, consultants, NGOs, academia, and interested parties who participate in Basin Characterization efforts. The BCX also plays a pivotal role in advancing the Basin Characterization Program’s activities and goals. BCX meetings will include regular updates from the Basin Characterization Program and participants can provide feedback and recommendations. Participants will also be provided with early opportunities to test data analysis tools and submit comments on draft process and guidance documents. BCX meetings are (generally) held the 3rd Tuesday of the month from 12:30 - 1:30 pm (PST).

Join the BCX listserv to become a BCX member and receive meeting registration emails. Check the BCX Hub for the upcoming schedule and past meeting materials.

The purpose of this shapefile is to provide an accurate boundary reference for the purpose of mapping and data analysis. Boundary of the combined adjudicated Central and West Coast groundwater basins. Adjudication is a form of groundwater management in California through the courts. When groundwater resources do not meet water demands in an area, landowners may turn to the courts to determine how much groundwater can be rightfully extracted by each overlying landowner or appropriator. The court typically appoints a Watermaster to administer the judgment and to periodically report to the court. As of 2013, there were 24 adjudicated groundwater basins in California, with the majority of the adjudications located in Southern California in the South Coast hydrologic region. The majority of groundwater rights adjudications in California imposes extraction limits and/or initiates management actions in the event of declining groundwater levels or water quality degradation. It should be noted that the primary objective of adjudication is to provide a proportionate share of the available groundwater to the users within the basin so it can be extracted without having adverse effects to existing groundwater supplies. Environmental concerns were not considered when most of the judgments were written. These data were developed using the best available data for the California Water Plan Update 2013, however may contain errors.