Bulletin 118: California's Groundwater (2003)

California Department of Water Resources (DWR) | October 1st, 2003

Despite California?s heavy reliance on groundwater, basic information for many of the groundwater basins is lacking. Particular essential data necessary to provide for bo

Despite California?s heavy reliance on groundwater, basic information for many of the groundwater basins is lacking. Particular essential data necessary to provide for both the protection and optimal use of this resource is not available. To this end, the California Legislature mandated in the Budget Act of 1999 that DWR prepare:  " ...the statewide update of the inventory of groundwater basins contained in Bulletin 118-80, which includes, but is not limited to, the following: the review and summary of boundaries and hydrographic features, hydrogeologic units, yield data, water budgets, well production characteristics, and water quality and active monitoring data; development of a water budget for each groundwater basin; development of a format and procedures for publication of water budgets on the Internet; development of the model groundwater management ordinance; and development of guidelines for evaluating local groundwater management plans. This report is organized into the following topics: Groundwater is one of California?s most important natural resources, and our reliance on it has continued to grow (Chapter 1). Groundwater has a complex legal and institutional framework in California that has shaped the groundwater management system in place today (Chapter 2). Groundwater management occurs primarily at the local water agency level, but may also be instituted at the local government level. At the request of the Legislature, DWR has developed some recommendations for a model groundwater management ordinance and components for inclusion in a groundwater management plan (Chapter 3). Groundwater has had a flurry of activity in the Legislature and at the ballot box in recent years that will affect the way groundwater is managed in California (Chapter 4). Groundwater programs with a variety of objectives exist in many State and federal agencies (Chapter 5). Groundwater concepts and definitions should be made available to a wide audience (Chapter 6). Groundwater basins with a wide range of characteristics and concerns exist in each of California?s 10 hydrologic regions (Chapter 7).

Bulletin 118: California's Groundwater (Interim Update 2016)

California Department of Water Resources (DWR) | December 22nd, 2016

A new era for California’s groundwater began in September 2014 with the passage of the Sustainable Groundwater Management Act (SGMA). SGMA established a path for the su

A new era for California’s groundwater began in September 2014 with the passage of the Sustainable Groundwater Management Act (SGMA). SGMA established a path for the sustainable management of groundwater through the formation of locally organized groundwater sustainability agencies and locally developed groundwater sustainability plans. The purpose of this interim update is to provide up-to-date information on groundwater basins subject to critical conditions of overdraft, groundwater basin boundaries, and basin prioritization. That information is essential to the successful implementation of SGMA, including the timely formation of groundwater sustainability agencies and the development of groundwater sustainability plans.

Bulletin 118: California's Groundwater Update 2020 (draft)

California Department of Water Resources (DWR) | March 1st, 2021

Groundwater is a precious and limited resource that is used in meeting the needs of California’s large and small urban areas, rural groundwater users, irrigated agricul

Groundwater is a precious and limited resource that is used in meeting the needs of California’s large and small urban areas, rural groundwater users, irrigated agriculture, and the environment. Since the last California’s Groundwater (CalGW) Update in 2003, there has been significant changes to land use, water use, water application practices, and water allocations. In addition, the effects of climate change have affected California’s reliance on groundwater. It is expected that there will be additional changes in land use, water use, adjustments in water allocations, and that climate change will continue to affect the environment, thus elevating the importance of the reporting in CalGW Updates.  According to the last comprehensive report, California’s Groundwater Update 2003 (CalGW Update 2003), California’s reliance on groundwater was approximately 30 percent during a wet-to-average precipitation water year and approximately 40 percent during dry periods. Since then, the percentage of groundwater reliance has increased to between 30 and 40 percent during above normal to-wet years and to as much as 58 percent during dry periods (California Department of Water Resources 2018).

Bulletin No. 39-C, South Coastal Basin Investigation, Records of Water Levels at Wells for the Year 1934, Precipitation Records for the Season 1933-34

California Department of Water Resources (DWR) | January 1st, 1935

Bulletin No. 39, South Coastal Basin Investigation, Records of Ground Water Levels at Wells

California Department of Water Resources (DWR) | December 1st, 1932

Bulletin No. 52-B Salinas Basin Investigation Summary Report

California Department of Water Resources (DWR) | December 13th, 1946

The Board of Supervisors and the Flood Control and Water Conservation Conmittee of the County of Monterey became concerned in April 1944 over the intrusion of saline wate

The Board of Supervisors and the Flood Control and Water Conservation Conmittee of the County of Monterey became concerned in April 1944 over the intrusion of saline water in the ground water supply utilized for irrigation, domestic and industrial purposes in the lower reaches of the Salinas Basin near Monterey Bay. The entire agricultural and urban development in the basin depends on an adequate supply of ground water of good quality. There had been some abandonment of wells in the Salinas Basin near the bay shore due to excessive salinity as early as 1938. Accelerated encroachment of the contamination occurred in 1943, and the matter was brought to public attention in 1944. The County of Monterey and the Department of Public Works, State of California, executed a contract on July 10, 1944, providing for maintenance in cooperation an investigation of the water resources of the Salinas Valley in Monterey County and conditions relative thereto which obtain in the valley or affect the water supplies available therefor. It further provides that the Department shall prepare a report based on the investigation setting forth the physical facts pertinent to water supply and to salt water Intrusion, and if possible, incorporate findings as to a method or methods of solving the problems involved.

Bulletin No. 84 Mojave River Ground Water Basins Investigation

California Department of Water Resources (DWR) | August 15th, 1967

Click here for Bulletin No. 84 maps and plates.

Click here for Bulletin No. 84 maps and plates.

Butte Subbasin Groundwater Sustainability Plan

Publisher not available | December 1st, 2021

The Butte Subbasin is identified by California Department of Water Resources (DWR) as a medium priority basin. Therefore, the Butte Subbasin GSAs must develop, adopt, and

The Butte Subbasin is identified by California Department of Water Resources (DWR) as a medium priority basin. Therefore, the Butte Subbasin GSAs must develop, adopt, and submit a GSP (or GSPs) to DWR for the entire Butte Subbasin by January 31, 2022. The Butte Subbasin is managed by eleven GSAs, which are working together under a Subbasin Cooperation Agreement1 to develop one GSP for the entire Subbasin. This Butte Subbasin GSP satisfies the requirements established by SGMA and DWR, and outlines the strategy by which the Butte Subbasin GSAs will maintain sustainable groundwater management through the implementation period until 2042.

Butte Valley Groundwater Sustainability Plan

Siskiyou County Flood Control and Water Conservation District | January 4th, 2022

California Groundwater Units

U.S. Geological Survey (USGS) | June 5th, 2014

The California Groundwater Units dataset classifies and delineates areas within the State of California into one of three groundwater-based polygon units: (1) those areas

The California Groundwater Units dataset classifies and delineates areas within the State of California into one of three groundwater-based polygon units: (1) those areas previously defined as alluvial groundwater basins or subbasins, (2) highland areas that are adjacent to and topographically upgradient of groundwater basins, and (3) highland areas not associated with a groundwater basin, only a hydrogeologic province. In total, 938 Groundwater Units are represented. The Groundwater Units dataset relates existing groundwater basins with their newly delineated highland areas which can be used in subsequent hydrologic studies. The methods used to delineate groundwater-basin-associated highland areas are similar to those used to delineate a contributing area (such as for a lake or water body); the difference is that highland areas are constrained to the immediately surrounding upslope (upstream) area. Upslope basins have their own delineated highland. A geoprocessing tool was created to facilitate delineation of highland areas for groundwater basins and subbasins and is available for download.