California's Groundwater (Bulletin 118)

California’s Groundwater (Bulletin 118) is the State’s official publication on the occurrence and nature of groundwater in California. 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.

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Bulletin 118 Fact Sheet ( PDF)

Two-page description of the upcoming comprehensive Bulletin 118 Update 2020, including a link to a Bulletin 118 user questionnaire.

Tags: Groundwater-Management, Bulletin-118

Hoja Informativa del Boletín 118 (Español PDF)

Descripción de dos páginas de la próxima actualización comprensivo del Boletín 118 de 2020, incluyendo un enlace a un cuestionario de usario del Boletín 118.

Tags: Groundwater-Management, Bulletin-118

California's Groundwater FAQ ( PDF)

Frequently asked questions, and corresponding answers, related to California’s Groundwater

Tags: Groundwater-Management, Bulletin-118

Preguntas Frecuentes sobre el Agua Subterránea de California (Español PDF)

Preguntas frecuentes y respuestas correspondientes relacionadas con el agua subterránea de California

Tags: Groundwater-Management, Bulletin-118

Legislation Timeline

Timeline of California’s Groundwater (Bulletin 118)

NOTE: Copies of all historic publications are available by request. Email sgmps@water.ca.gov.

1956

California Department of Water Resources (DWR) established.

1975

The 93rd United States Congress passed the Safe Drinking Water Act.

1978

California Senate Bill 1505 passed. Required DWR to work with public agencies to conduct an investigation of the state’s groundwater basins and to look at patterns of groundwater pumping recharge to identify basins subject to critical conditions of overdraft.

1992

Assembly Bill 3030, the Groundwater Management Act, passed. Required formal, but voluntary groundwater management planning for the first time in California.

1999

California Legislature Budget Act of 1999 authorized funding for B-118 Update 2003 and directed DWR to complete several tasks including developing criteria for evaluation of groundwater management plans and developing a model groundwater management ordinance.

2002

Senate Bill 1938 passed. Expanded groundwater management plan requirements beyond those of Assembly Bill 3030.

2009

Senate Bill x7-6 passed: California Statewide Groundwater Elevation Monitoring (CASGEM) Program

2011

Assembly Bill 359 passed. Required that groundwater management plans map and report groundwater recharge areas.

2014

Governor Jerry Brown released initial California Water Action Plan. Set forth 10 priority actions that guide the state’s effort to create more resilient, reliable water systems and to restore critical ecosystems.

2014

The Sustainable Groundwater Management Act (SGMA) signed into law. Provided framework for required groundwater management in medium- and high-priority basins.

2016

Governor Jerry Brown released final California Water Action Plan.

Publications Timeline

Timeline of California’s Groundwater (Bulletin 118)

NOTE: Copies of all historic publications are available by request. Email sgmps@water.ca.gov.

1952

Water Quality Investigations Report No. 3 Ground Water Basins in California (predecessor of Bulletin 118) was published by the California Department of Public Works, Division of Water Resources (predecessor of DWR). Created a base index map of the "more important groundwater basins."

Identified 286 alluvium-filled valleys believed to be basins with usable groundwater.
Created a statewide numbering system based on the boundaries of the nine Regional Water Quality Control Boards.

1966

Bulletin 118-2 published: Evaluation of Ground Water Resources: Livermore and Sunol Valleys Appendix A: Geology

1967

Bulletin 118-1 published: Evaluation of Groundwater Resources: South San Francisco Bay Appendix A. Geology

1968

Bulletin 118-1 published: Evaluation of Groundwater Resources: South San Francisco Bay Volume 1. Fremont Study Area

1973

Bulletin 118-1 published: Evaluation of Groundwater Resources: South San Francisco Bay Volume 2. Additional Fremont Study Area

1974

Bulletin 118-2 published: Evaluation of Ground Water Resources: Livermore and Sunol Valleys

1974

Bulletin 118-3 published: Evaluation of Ground Water Resources: Sacramento County

1975

DWR published Bulletin 118-75 California's Ground Water.

Identified 459 groundwater basins and subbasins in California and provided summary information on basin and aquifer characteristics, groundwater use, and water quality concerns.
Summarized technical information for 248 groundwater basins, and mapped their locations.
Included water-bearing material, well yields in the basin, depth of water bearing zones, storage capacity, usable capacity, extent of basin development, degree of knowledge of the basin, and local groundwater-related problems.

1975

Bulletin 118-4 published: Evaluation of Ground Water Resources: Sonoma County Volume 1. Geologic and Hydrologic Data

1975

Bulletin 118-1 published: Evaluation of Groundwater Resources: South San Francisco Bay Volume 3. Northern Santa Clara County

1978

Bulletin 118-6 published: Evaluation of Ground Water Resources: Sacramento Valley

1980

DWR published Bulletin 118-80: Ground Water Basins in California: A Report to the Legislature in Response to Water Code Section 12924.

Identified 471 groundwater basins/subbasins.
Summarized information on basin characteristics, groundwater use, and included maps of areal extent.
Included descriptions of basin settings and boundaries for selected basins.
Identified 11 critically overdrafted groundwater basins and four basins with "special problems."

1981

Bulletin 118-1 published: Evaluation of Groundwater Resources: South San Francisco Bay Volume 4. South Santa Clara County

1982

Bulletin 118-4 published: Evaluation of Ground Water Resources: Sonoma County Volume 2. Santa Rosa Plain

1982

Bulletin 118-4 published: Evaluation of Ground Water Resources: Sonoma County Volume 3. Petaluma Valley

1982

Bulletin 118-4 published: Evaluation of Ground Water Resources: Sonoma County Volume 4. Sonoma Valley

1983

Bulletin 118-4 published: Evaluation of Ground Water Resources: Sonoma County Volume 5. Alexander Valley and Healdsburg Area

2003

DWR published Bulletin 118-03 California's Ground Water: Update 2003

Contained a status report on groundwater management in California and an inventory of California’s groundwater information.
Identified 515 basins/subbasins, and listed and mapped them by hydrologic region.
Included a map of the region groundwater development, general groundwater quality information, and changes in any basins from earlier B-118 reports. The list of critically overdrafted groundwater basins, published in the 1980 update of Bulletin 118, was not reevaluated for Update 2003.
Included groundwater data tables for each hydrologic region, the basins/subbasins, each basin’s area, a groundwater budget based on the level of basin knowledge, maximum and average well yields (if known), types of groundwater monitoring in the basin, and average and range of total dissolved solids concentrations (if known).
Created an online supplement to the Bulletin-118 Update 2003 text, including a GIS data file containing the basin boundaries of all 515 basins.
Included separate text descriptions of the basins, and additional information compiled by DWR staff, such as a physical basin boundary description, hydrologic setting and hydrogeology of the basin, the degree of groundwater development in the basin, specific yields of aquifers (if known), groundwater management occurring in the basin, water quality and known issues, and references.

2013

DWR published California’s Water Plan - Groundwater Update 2013, a comprehensive groundwater update, as part of the California Water Plan Update 2013.

While not a formal Bulletin-118 document, the 2013 Groundwater Update contained the most detailed information on California's groundwater resources and additional chapters for each of the 10 hydrologic regions of California.

2016

DWR published California’s Groundwater – Interim Update 2016. Two requirements of SGMA made it necessary to publish an Interim Bulletin 118 Update in 2016, before the comprehensive update in 2020.

SGMA established the basin boundary modification process which allowed local groundwater sustainability agencies to request modifications to their basin boundaries for either scientific or jurisdictional reasons. Finalized basin boundary modifications became official when published in the 2016 Interim Bulletin-118 Update. A total of 517 basins/subbasins were identified in the 2016 Interim Update.
DWR updated the methodology of analysis for conditions of critical overdraft and identified 21 critically overdrafted groundwater basins (up from 11 in 1980). The methodology and findings became official once the 2016 Interim Update was published. SGMA required critically overdrafted basins to submit groundwater sustainability plans two years earlier than high- and medium-priority basins.

2020

DWR publishes California's Groundwater Update 2020, the first Bulletin 118 five year update as required by SGMA.

Bulletin 118 statewide reports provide information about the nature and occurrence of groundwater in California with a focus on the state's groundwater basins.

Bulletin 118 - Interim Update 2016 ( PDF) | (Publish Date: Dec 22, 2016) Version:

Update 2016 updates portions of Bulletin 118 Update 2003 and includes time-sensitive information important to implementing the new Sustainable Groundwater Management Act (SGMA). Additionally, a new procedure for basin descriptions was developed as part of the basin boundary modification process. All basins with boundary modifications in 2016 have revised basin boundary descriptions that replace their 2003 descriptions.

Tags: Groundwater-Management, Sustainable-Groundwater-Management-ActBulletin-118, Groundwater-Basin-Boundaries, Sustainable-Groundwater-Management-Act

Bulletin 118 - Update 2003 ( ) | (Publish Date: Oct 01, 2003)

Update 2003 is the most recent comprehensive report on groundwater. It describes California’s groundwater basins and subbasins, including basin boundaries, hydrologic and hydrogeologic summaries, groundwater storage capacity and water budget, groundwater level and quality trends, well yields, basin management, and references.

Bulletin 118-80 - Ground Water Basins in California: A Report to the Legislature in Response to Water Code Section 12924 ( ) | (Publish Date: Jan 01, 1980)

This report, prepared under Senate Bill 1505, Chapter 601, Statutes of 1978, Section 12924 of the California Water Code, identifies the State's groundwater basins on the basis of geological and hydrological conditions and consideration of political boundary lines whenever practical. This report also contains existing general patterns of ground water pumping and ground water recharge within such basins to the extent necessary to identify basins which are subject to critical conditions of overdraft.

Bulletin 118-75 - California's Ground Water ( ) | (Publish Date: Sep 01, 1975)

Conclusions and recommendations are presented in Chapter I. Chapter II describes groundwater as a resource. Chapter III contains tabular summaries of information for 248 of the more important ground water basins, along with maps showing their locations. It provides references to 194 of the Department of Water Resources' reports on these basins and to 185 reports of other agencies. Chapter IV discusses ground water basin protection and utilization, and Chapter V describes opportunities for basin management and desirable future studies.

Ground Water Basins in California, Water Quality Investigations Report No. 3 ( ) | (Publish Date: Nov 01, 1952)

This report identifies the areas of alluvial-fill in the State of California which may be areas of groundwater storage. It establishes a uniform name an numbering system for groundwater basins which can be expanded as new areas of storage are identified. A selected bibliography pertaining to groundwater resources in California is included.

In addition to the statewide editions of Bulletin 118, DWR has published the following limited Bulletin 118 reports that focus on specific areas of the state.

Bulletin 118-1 - South San Francisco Bay

Volume 1 - Fremont Study Area ( ) | (Publish Date: Aug 01, 1968)

Volume 2 - Additional Fremont Study Area ( ) | (Publish Date: Aug 01, 1973)

Volume 3 - Northern Santa Clara County ( ) | (Publish Date: Dec 01, 1975)

Volume 4 - South Santa Clara County ( ) | (Publish Date: Jan 01, 2015)

Appendix A - Geology ( ) | (Publish Date: Aug 01, 1967)

Bulletin 118-2 - Livermore and Sunol Valleys

Bulletin 118-2 - Livermore and Sunol Valleys ( ) | (Publish Date: Jun 01, 1974)

Appendix A - Geology ( ) | (Publish Date: Aug 01, 1966)

Bulletin 118-3 - Sacramento County

Bulletin 118-3 - Sacramento County ( ) | (Revision Date: Apr 01, 1980) (Publish Date: Jul 01, 1974)

Bulletin 118-4 - Sonoma County

Content goes here

Volume 1 - Geologic and Hydrologic Data ( ) | (Publish Date: Dec 01, 1975)

Volume 2 - Santa Rosa Plain ( ) | (Publish Date: Sep 01, 1982)

Volume 3 - Petaluma Valley ( ) | (Publish Date: Jun 01, 1982)

Volume 4 - Sonoma Valley ( ) | (Publish Date: Feb 01, 1982)

Cover of B118 report Alexander Valley in 1983.

Volume 5 - Alexander Valley and Healdsburg Area ( ) | (Publish Date: Jun 01, 1983)

Bulletin 118-6 - Sacramento Valley

Bulletin 118-6 - Sacramento Valley ( ) | (Publish Date: Aug 01, 1978)

B118 Update 2003 provided online descriptions of California’s groundwater basins and subbasins. The 2003 Basin Descriptions included available information on narrative descriptions of basin boundaries, summaries of the hydrologic and hydrogeologic setting, groundwater storage capacity and water budget, groundwater level and quality trends, well yields, basin management, and references.

The full 2003 Basin Descriptions have not been updated for B118 Interim Update 2016; however, we developed a new procedure for basin boundary descriptions as part of the 2016 Basin Boundary Modification process. As a result, all basins that had boundary modifications in 2016 have revised basin boundary descriptions. We will update basin description information as GSAs implement their GSPs and new and additional information becomes available.

View 2016 Basin Boundary Descriptions

View 2003 Basin Descriptions

NOTE: The basin boundary descriptions contained in the 2003 basin descriptions are no longer valid for the basins with revised boundaries.

View Map in New Window

A GIS data set, containing the boundaries for each of California's groundwater basins, is available for download. The compressed downloaded file contains both a shapefile of the basin boundary data, and a geodatabase containing a basin boundary feature class. Metadata is included with each version of the basin boundary data set.

Bulletin 118 Basin Boundary GIS Data

The Bulletin 118 Basin Boundary GIS data can also be accessed through the California Natural Resources Agency’s Open Data Portal. There you will find additional formats, including GeoJSON and KML, available for download. It should be noted that the shapefile available for download on the Open Data web site is projected in WGS84 Web Mercator.

Bulletin 118 Groundwater Basins - Open Data

CASGEM

California Statewide Groundwater Elevation Monitoring (CASGEM) Program - collaboration between local monitoring parties and DWR to collect groundwater elevations statewide and make that information publicly available.

Data & Tools

Data & Tools We have a long history of data collection, monitoring, and reporting. With the passage of the Sustainable Groundwater Management Act (SGMA), there is an increased need for local and state agencies and the public to easily access water data in order to make informed management decisions. Here you will find a curated set of data, interactive mapping tools, and reports which are important resources to inform sustainable groundwater management decision-making.

California's Groundwater (Bulletin 118)

Legislation Timeline

Timeline of California’s Groundwater (Bulletin 118)

1956

1975

1978

1992

1999

2002

2009

2011

2014

2014

2016

Publications Timeline

Timeline of California’s Groundwater (Bulletin 118)

1952

1966

1967

1968

1973

1974

1974

1975

1975

1975

1978

1980

1981

1982

1982

1982

1983

2003

2013

2016

2020

Bulletin 118-1 - South San Francisco Bay

Bulletin 118-2 - Livermore and Sunol Valleys

Bulletin 118-3 - Sacramento County

Bulletin 118-4 - Sonoma County

Bulletin 118-6 - Sacramento Valley

CASGEM

Data & Tools

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