Forty Two Percent of Public Water Supply Wells in California’s San Joaquin Valley Vulnerable, Finds New Report

Forty Two Percent of Public Water Supply Wells in California’s San Joaquin Valley Vulnerable, Finds New Report

June 22, 2021, Oakland, California – Forty two percent of shallow wells supplying water to community water systems in California’s San Joaquin Valley are vulnerable to going partially or fully dry under the state’s minimum thresholds, finds a new report from the Pacific Institute. Most impacted wells are shallower, and tend to be in disadvantaged communities.  

At Risk: Public Supply Well Vulnerability Under California’s Sustainable Groundwater Management Act examines the vulnerability of public water supply wells and the water systems they support in the San Joaquin Valley under the minimum groundwater levels established in the state’s Sustainable Groundwater Management Act. It finds that about 70% of water systems in the region’s groundwater sustainability plans have at least one well that would be partially or fully dry at minimum thresholds. Nearly 120 water systems, serving 1.35 million people, would face more severe challenges, with over 30% of each water system’s wells impacted. Meanwhile, small water systems and water systems serving populations whose households make less than $75,000 per year are likely to face the most severe impacts.  

 “California’s Sustainable Groundwater Management Act was designed to prevent significant lowering of groundwater levels across the state, but we found that shallow wells are not protected,” explains report author Darcy Bostic of the Pacific Institute. “This threatens the realization of California’s Human Right to Water, which states that every person has the right to safe, clean, affordable, and accessible water.”  

During the 2012-2016 California drought, many domestic wells and some public water supply wells went dry. The report includes recommendations to protect shallow wells in the future, including: 

  • The Department of Water Resources should ensure groundwater sustainability plans incorporate the Human Right to Water in their minimum thresholds and well mitigation plans; 
  • Groundwater Sustainability Agencies should be prepared to support small water systems and domestic wells with additional data collection on who is vulnerable, robust mitigation frameworks or well protection plans, support in searching for alternative water supplies, and consolidation efforts; and   
  • Centralized, standardized, and publicly available data and methods for assessing the impacts of a range of minimum water threshold options on groundwater wells should be readily accessible. 

Learn more and download the report here.  


Founded in 1987, the Pacific Institute is a global water think tank that combines science-based thought leadership with active outreach to influence local, national, and international efforts in developing sustainable water policies. The Pacific Institute’s mission is to create and advance solutions to the world’s most pressing water challenges. Through an interdisciplinary and nonpartisan approach, the Institute actively collaborates with a diverse set of stakeholders, including policymakers, scientists, corporate leaders, international organizations such as the United Nations, advocacy groups, and local communities. 

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