P.O. Box 239 | Somis, CA 93066

Sustainable Groundwater Management Act (SGMA)

On January 1, 2015, the Sustainable Groundwater Management Act (SGMA) became effective signaling a new era in groundwater management in California. The SGMA of 2014 is a tripartite package that establishes a new structure for local authorities to sustainably manage their groundwater basins, with a limited role for state intervention only if necessary. The legislation lays out a process and timeline for local authorities to achieve sustainable management of groundwater basins. The act requires the formation of local groundwater sustainability agencies (GSAs) that must assess conditions in their local groundwater basins and adopt locally-based management plans for certain basins. 

Groundwater basins designated as high or medium priority and critically overdrafted must be managed under a groundwater sustainability plan (GSP) or a coordinated groundwater sustainability plan by January 31, 2020. All other high and medium priority basins must be managed under a GSP by January 31, 2022. The Las Posas Valley Groundwater Basin is designated as a "high priority" basin.

SGMA allows local agencies to adopt groundwater management plans that are tailored to the resources and needs of their communities. 

Once plans are in place, local agencies have 20 years to fully implement them and achieve the sustainability goal. SGMA does not change existing surface water and groundwater rights. Groundwater rights will continue to be subject to regulation under the California Constitution (per Water Code Section 10720.5). 

Click below for more information.

SGMA Portal

Basin Prioritization

In 2009, The California Department of Water Resources (DWR) implemented the California Statewide Groundwater Elevation Monitoring (CASGEM) Program to establish a permanent, locally managed groundwater level monitoring program to track seasonal and long-term trends in groundwater levels.


As part of CASGEM, the DWR prioritized California’s groundwater basins in 2014 to identify the need for additional monitoring. Basin prioritization is a statewide ranking of the overall importance of groundwater to meet urban and agricultural demands of the overlying population. The ranking does not characterize how the basins are managed, monitored, or capture the importance of smaller size or lower-use groundwater basins. The goal of the program is to ensure a reliable water supply for future generations. 

In 2016, the DWR received numerous requests for basin boundary modifications and when finalized, prompted basin prioritization reassessment. DWR released the final basin prioritization results in January 2019 for 458 of the 517 basins. The remaining 59 basins are pending a boundary modification request. 

There are 23 state recognized groundwater basins in Ventura County. Four are designated as “high priority” basins, one is designated as “medium priority,” eleven are “low priority” and the remaining seven basins are pending a boundary modification request. The statewide summary of the CASGEM basin prioritization results can be viewed on the DWR’s website by clicking below.

DWR Basin Prioritization


When there is dispute over legal rights to the water, a court can issue a ruling known as an adjudication. According to SGMA, adjudicated basins do not need a GSA or a GSP but must still provide groundwater measurements to the Department of Water Resources (DWR).

During the adjudication process, the court will also define the area of adjudication, the groundwater rights of all users, who the owners are, and how much groundwater those owners can extract. The court also appoints a Watermaster to ensure the basin is managed in accordance with the court’s decree. 

The Santa Paula Basin is the only adjudicated basin in Ventura County. 

On March 28, 2018, the Las Posas Basin Water Rights Coalition (LPBWRC) has filed a comprehensive adjudication litigation for the Las Posas Groundwater Basin against the Fox Canyon Groundwater Management Agency.  

Zone Water

Zone’s water wells draw water from the Las Posas Valley Groundwater Basin, a basin currently designated “high priority.” The designation requires the formation of a Groundwater Sustainability Agency (GSA) to adopt a management plan for the basin. The Fox Canyon Groundwater Management Agency (FCGMA) is the GSA for the areas of the Las Posas Valley Basin within its jurisdictional boundaries. Camrosa Water District is the GSA for the area outside of the FCGMA boundary. The FCGMA and Camrosa will coordinate management of the entire Las Posas Valley Basin. Work is underway to develop a Groundwater Sustainability Plan (GSP) that will outline how the basin will reach long term sustainability.