DWR: Local agencies across California continue advancements toward groundwater sustainability ~ MAVEN'S NOTEBOOK

From the Department of Water Resources:

The Department of Water Resources (DWR) has released the final version of California’s Groundwater: Bulletin 118 – Update 2025, the State’s official and most comprehensive report of groundwater monitoring, conditions, and management across California. The report builds upon the previous update in 2020 and contains critical information about the state’s groundwater supplies from 2020 to 2024, a period marked by record-setting dry and wet weather events and increasing ambient temperatures. It shows considerable progress made by California and local agencies towards reaching the goals of groundwater sustainability outlined in the Sustainable Groundwater Management Act (SGMA). Among the successes noted in the report, California has seen improvements in groundwater recharge efforts, drinking well protection, and increased funding for Tribal projects.

This release coincides with Groundwater Awareness Week, a time to recognize the vital role groundwater plays in California’s water supply.

“Groundwater plays a critical role in our state’s water supply and today’s report shows what we’ve already known: our changing climate and warmer temperatures will continue to increase demand on groundwater supplies as our hydrology changes and tests our water systems,” said Paul Gosselin, DWR Deputy Director of Sustainable Water Management. “It’s more important than ever that state and local agencies continue to work together to achieve the goals we set for California in order to protect this precious resource and the people who rely on it.”

The publication also presents findings and recommendations that support the future management and protection of groundwater in alignment with the state’s key water initiatives including the California Water Plan, the Water Resilience Portfolio, and Water Supply Strategy.

Key findings from the report:

California’s groundwater basins are the state’s largest and lowest cost water storage and a critical natural infrastructure asset, with storage capacity exceeding 1 billion acre feet, about 25 times all surface reservoirs combined. Sustainable yield in high and medium priority basins is about 12 million acre feet annually.
Groundwater is central to California’s water resilience, supplying about 40 percent of statewide demand in average years and nearly 60 percent in dry years. The driest 22-year stretch in at least 1,200 years, including four major droughts (2001 to 2002, 2007 to 2009, 2012 to 2016, and 2020 to 2022), has increased both reliance on and stress to groundwater.
From 2020 to 2022, California experienced its three driest consecutive years on record leading to reduced surface water supplies and increased reliance and stress on groundwater basins. As a result, hundreds of wells went dry across the state, and many groundwater basins are still recovering.
More than 32 million Californians (about 82 percent) rely on groundwater for some portion of their water supply, including over 7 million people in non-basin areas where it is often the only source. Groundwater use is about 79 percent agriculture, 19 percent urban, and 2 percent managed wetlands.
Management and data improvements are accelerating in the state’s highest use basins. The 94 high and medium priority basins account for about 95 percent of groundwater pumping. Groundwater Sustainability Plan (GSP) annual reports compiled by groundwater sustainability agencies (GSAs) now serve as the most comprehensive statewide groundwater data source.
Groundwater levels show early signs of improvement, but significant challenges remain. From 2014 to 2024, 41 percent of monitored wells rose five feet or more, while about 20 percent declined by five feet or more. Despite these gains, land subsidence continues to be widespread and impactful, with about 4,000 square miles experiencing more than 0.5 feet of subsidence in the past five years.
SGMA has spurred more than 1,500 local projects and management actions. Their estimated cost is in the billions, underscoring the scale of effort ahead and the importance of continued collaboration, improved measurement, and coordinated management across local, state, and federal partners to support long term sustainability.

Significant actions since 2020:

The Newsom Administration released the Water Resilience Portfolio (2020) and California’s Water Supply Strategy (2022), which set goals to continue implementing SGMA and to increase annual groundwater recharge by 500,000 acre-feet. Since setting these goals, local GSAs have advanced GSP implementation and assembled more than 1,500 projects and management actions, and achieved an annual average reported managed recharge of approximately 2.5 million acre-feet across Water Year (WY) 2022 (Critical), WY 2023 (Wet), and WY 2024 (Above Normal), resulting in a cumulative three-year total of 7.4 million acre-feet of reported recharge.
DWR has allocated over $500 million in sustainable groundwater management planning and implementation grants across the state. Additional funding for Department technical assistance programs, such as the Basin Characterization Program and Statewide Groundwater Monitoring Program, provides the latest data and fills data gaps that lead to an increase in information about California’s groundwater basins, which help local communities better understand their aquifer
The LandFlex Grant Program provided approximately $25 million in grants for immediate drought relief by compensating growers who voluntarily reduce pumping to protect nearby drinking water wells. As a result, the program helped save over 100,000 acre-feet of groundwater, protected 16,500 drinking water wells, and reduced over-pumping of groundwater on Central Valley farms.
Efforts have included the $15 million funding agreement for Tribal water supply projects and the establishment of the Underrepresented Communities Groundwater Technical Assistance Program.

Staying Informed on California’s Groundwater

Across the state, over 80 percent of Californians rely on groundwater for some portion of their water needs. On average, groundwater accounts for about 40 percent of California’s total annual water supply and serves as a critical buffer during dry periods, supplying up to 60 percent of the state’s water in drought years. With climate change likely to cause likely prolonged periods of drought and less snowpack into the future, the State is continuing to invest in efforts and data collection to be better prepared for future droughts and increase resiliency.

Previously, Bulletin 118 was updated every five years. Under new legislation, California’s Groundwater: Bulletin 118 Updates will be published every 10 years to provide a comprehensive summary of the state of the State’s Groundwater. Between these larger and infrequent updates, Californians can stay informed through DWR’s California’s Groundwater Semi-Annual Groundwater Updates, released every spring and fall, and by visiting California Groundwater Live for near real-time information. Together, these resources paired with DWR’s financial and technical assistance services help local groundwater sustainability agencies monitor conditions in their region and adjust custom-tailored solutions to meet sustainability objectives.

For more information: