In 2014, the California State Legislature enacted the Sustainable Groundwater Management Act (SGMA), which requires the formation of new local agencies, known as Groundwater Sustainability Agencies (GSAs), to sustainably manage groundwater basins throughout the state.  The statute represents the first statewide framework for groundwater management in California.  Among other tasks, GSAs, especially those in overdrafted basins, will have to allocate available water among users and set up systems to hold pumpers to their allocated limit.  However, SGMA did not change the longstanding framework of groundwater pumping rights established by California courts.  This sets up the possibility of conflict between groundwater allocation plans adopted by GSAs and water rights.

This Article analyzes the relationship between SGMA and water rights under the common law.  It identifies a path for GSAs to allocate groundwater and limit pumping in a manner best situated to sustain judicial scrutiny.  We examine how the common law defines water right priorities for groundwater pumping allocations, as well as areas where the common law provides flexibility.  This flexibility allows for creativity in arriving at allocations that fit stakeholders’ goals for both sustainable and smart water management.  We seek to help GSAs reduce the risk of litigation and increase the likelihood their Groundwater Sustainability Plan (GSP) will survive litigation, without judicial modification.  There are considerable measures GSAs can take to manage their litigation risk and enhance the durability of their GSPs, including making groundwater allocations in their GSPs consistent with the principles of water rights and seeking consensus among affected stakeholders.  We also seek to provide a framework for courts to work out the appropriate relationship between SGMA and the common law of water rights when litigation occurs.