Groundwater is a critical resource in California, providing approximately forty percent of the state’s water supply and significantly more during dry years. Local management agencies, court-adjudicated regimes - where water users turn to the court to define and assign private property rights over groundwater and to oversee the rules governing basin management, and special act districts - created by legislative statue that allows for enhanced local regulation of groundwater, are the institutional arrangements to manage groundwater in the state. In 2014, the Sustainable Groundwater Management Act (SGMA), established new requirements for 127 basins in, or vulnerable to, overdraft to develop sustainable management programs with increased state oversight. But SGMA exempted all adjudicated basins and SGMA provides all special act districts with the right to be the exclusive local agencies within their statutory boundaries, and the option to be the sole GSA in their service area. The adjudicated basins and special act districts encompass major municipal and agricultural areas in the state, and special act districts are considered to be one model for sustainable groundwater management under SGMA.

In 2016, our research team completed a detailed evaluation of all the adjudicated basins for the SWRCB, and a similar evaluation of all the special act districts is pending. Our research team is continuing to analyze these and other groundwater basins to illuminate the comparative advantages of particular institutional arrangements, and what factors affected both the overall sustainability of each basin and were significant in reducing vulnerability to the 2012-2015 drought. 


Vulnerability to water shortages already exists in California due to both normal physical conditions that include high inter-annual variability in precipitation with periodic droughts and increased claims to water by more diverse interests. Climate change will exacerbate these existing vulnerabilities. In particular, it is predicted that there will be more frequent and extreme droughts in the state.

Traditional drought adaptation strategies typically focus on monitoring weather conditions, generating surface and groundwater data, and implementing water shortage contingency plans after a drought occurs. Desalination, recycled water, new surface storage facilities, and increased water use efficiency are commonly proposed approaches for balancing supply and demand during a drought.

While these strategies can be effective, they may also lead to pernicious unintended consequences. An increase in groundwater supply during a dry period can prompt growth during subsequent normal periods which increase future water requirements. Moreover, long-term demand reduction can result in a hardening of demand-side conservation capabilities during a future drought. This results in an increase of a region’s vulnerability to future water shortages.

We are exploring a proactive approach to increase a community’s resilience to future prolonged droughts - the establishment and maintenance of local strategic groundwater reserves. If, as projected by DWR, improvements to groundwater management are key strategies to generate more water to meet California’s growing demand, then it is critical that incentives be created to protect the quality and quantity of this water for future generations and to maintain a reserve for a long-term drought.