California's Groundwater Update 2025 (Bulletin 118)

California Department of Water Resources (DWR) | October 20th, 2025

California’s Groundwater: Bulletin 118 — Update 2025 (CalGW Update 2025) is a compendium of statewide data and information on the occurrence, nature, use, and conditi

California’s Groundwater: Bulletin 118 — Update 2025 (CalGW Update 2025) is a compendium of statewide data and information on the occurrence, nature, use, and conditions of California’s groundwater resources and management. Chapters 1-6 Chapter 7 Appendix A: Findings and Recommendations Appendix B: Glossary Appendix D: Citations, Reference Materials, and Links Appendix I: Land Subsidence  

California’s Groundwater Update 2013: A Compilation of Enhanced Content for California Water Plan Update 2013

California Department of Water Resources (DWR) | April 1st, 2015

The primary goal of California’s Groundwater Update 2013: A Compilation of Enhanced Content for California Water Plan Update 2013 (California’s Groundwater Update 201

The primary goal of California’s Groundwater Update 2013: A Compilation of Enhanced Content for California Water Plan Update 2013 (California’s Groundwater Update 2013) is to provide foundational information to improve the statewide and regional understanding of groundwater conditions and management programs. The set of data, information, and analyses developed by the California Department of Water Resources (DWR) will help set the stage for future Bulletin 118 and California Water Plan updates, and help local and regional agencies plan for sustainable groundwater management by providing an on-going reporting of essential groundwater data, information, and analyses. A second goal is to identify data gaps and groundwater management challenges that are meant to serve as a guidepost for prioritizing future groundwater data collection and funding opportunities. The final goal is to develop a set of recommendations to improve groundwater management in California. Findings, data gaps, and recommendations were developed for the state as a whole and for each of the 10 hydrologic regions. Statewide findings, data gaps, and recommendations presented herein serve as a summary of those commonly identified at the regional level.

California’s Groundwater: Bulletin 118 — Update 2025 Highlights

California Department of Water Resources (DWR) | October 20th, 2025

California’s Groundwater: Bulletin 118 — Update 2025 (CalGW Update 2025) serves as the most up-to-date and comprehensive compendium of statewide data and information

California’s Groundwater: Bulletin 118 — Update 2025 (CalGW Update 2025) serves as the most up-to-date and comprehensive compendium of statewide data and information on the occurrence, nature, uses, management, climate change vulnerability, monitoring, and conditions of California’s groundwater resources. Building on the legacy of Bulletin 118 and past California Water Plans, CalGW Update 2025 synthesizes recent data — available up to December 2023 — and closes key knowledge gaps to inform more effective statewide groundwater planning and decision-making.  CalGW Update 2025 consists of this Highlights document and a detailed statewide report, supported by a series of appendices. 

Carbon Sequestration and Subsidence Reversal in the Sacramento–San Joaquin Delta and Suisun Bay: Management Opportunities for Climate Mitigation and Adaptation

University of California, Davis (UC Davis) | August 28th, 2023

Case History No. 9.14. Santa Clara Valley, California, U.S.A.

United Nations Educational, Scientific and Cultural Organization (UNESCO) | June 30th, 1984

Castac Lake Valley Groundwater Sustainability Plan

Castac Basin Groundwater Sustainability Agency | September 17th, 2020

The Castac Lake Valley Groundwater Basin (also referred to herein as “the Basin”), California Department of Water Resources (DWR) Basin No. 5-029, is located at the

The Castac Lake Valley Groundwater Basin (also referred to herein as “the Basin”), California Department of Water Resources (DWR) Basin No. 5-029, is located at the southern end of Kern County. The Basin is identified by DWR as being a very low priority basin, and as such, this GSP and associated SGMA compliance efforts have been conducted on a voluntary basis. Due to size, the file has been divided into two parts. Part 1, Part 2

Center for Biological Diversity vs. Lincoln County Water District

Nevada Appellate Courts | January 25th, 2024

This case examines whether the State Engineer has the authority to redesignate multiple existing hydrographic basins as one "superbasin" based on a shared source of water

This case examines whether the State Engineer has the authority to redesignate multiple existing hydrographic basins as one "superbasin" based on a shared source of water for purposes of the water's administration and management. We also look at whether the State Engineer complied with due process in creating the superbasin at issue here.

Central Kings Groundwater Sustainability Agency Groundwater Sustainability Plan

Central Kings Groundwater Sustainability Agency (CKGSA) | December 11th, 2019

Central Kings Groundwater Sustainability Agency Groundwater Sustainability Plan (Revised)

Central Kings Groundwater Sustainability Agency (CKGSA) | July 13th, 2022

Chapter A of Natural and Anthropogenic (Human-Made) Hexavalent Chromium, Cr(VI), in Groundwater near a Mapped Plume, Hinkley, California: Introduction to Study Area Hydrogeology, Chromium Sources, Site History, and Purpose of Study

U.S. Geological Survey (USGS) | April 25th, 2023

Documents in this series: Chapter A: Introduction to Study Area Hydrogeology, Chromium Sources, Site History, and Purpose of Study Chapter B: Survey of Chromium and

Documents in this series: Chapter A: Introduction to Study Area Hydrogeology, Chromium Sources, Site History, and Purpose of Study Chapter B: Survey of Chromium and Selected Element Concentrations in Rock, Alluvium, and Core Material Chapter C: Chromium in Minerals and Selected Aquifer Materials Chapter D: Analyses of Regulatory Water-Quality Data Chapter E: Groundwater Chemistry and Hexavalent Chromium Chapter F: Environmental Tracers of Groundwater Source, Age, and Geochemical Evolution Chapter G: Evaluation of Natural and Anthropogenic (Human-Made) Hexavalent Chromium Chapter H: Predevelopment Water Levels, Groundwater Recharge, and Selected Hydrologic Properties of Aquifer Materials, Hinkley and Water Valleys, California Chapter I: Sequestration and Reoxidation of Chromium in Experimental Microcosms Chapter J: Summary and Conclusions Between 1952 and 1964, hexavalent chromium, Cr(VI), was released into groundwater from the Pacific Gas and Electric Company (PG&E) Hinkley compressor station in the Mojave Desert 80 miles (mi) northeast of Los Angeles, California. Remediation began in 1992, and in 2010, site cleanup was projected to require between 10 and 95 years and was expected to cost between $36 and $176 million. A 2007 PG&E study estimated the natural Cr(VI) background in groundwater in Hinkley Valley to be 3.1 micrograms per liter (μg/L). This concentration was used for interim regulatory purposes by the Lahontan Regional Water Quality Control Board (RWQCB). In the fourth quarter (October–December) 2015, the regulatory Cr(VI) plume extended about 3.0 mi downgradient from the release location within the Hinkley compressor station, while groundwater having Cr(VI) concentrations greater than 3.1 μg/L was present more than 8 mi downgradient. Although rocks and minerals in the area are naturally low in chromium, alluvium eroded from the San Gabriel Mountains and transported to Hinkley Valley by the Mojave River, and locally small exposures of mafic rock, including hornblende diorite and basalt, may contribute Cr(VI) to groundwater. In response to limitations of the PG&E 2007 Cr(VI) background study’s methodology, uncertainty in the natural Cr(VI) background concentration, and an increase in the mapped extent of groundwater having Cr(VI) concentrations greater than the interim regulatory background of 3.1 μg/L, the Lahontan RWQCB concluded that the 2007 PG&E background Cr(VI) study should be updated. The purpose of the updated study is to estimate background Cr(VI) concentrations in groundwater within the upper aquifer upgradient, downgradient, near the margins, and within the footprint of the PG&E Cr(VI) plume in Hinkley, California. The scope of the study included eight tasks; results from those tasks are presented in the chapters within this professional paper.