Groundwater Sustainability Planning

The 2014 Sustainable Groundwater Management Act (SGMA) provides a framework for sustainable management of groundwater resources by local authorities. The act provides a timeline – 20 years – to implement actions that achieve long-term groundwater sustainability. It protects existing surface water and groundwater rights and does not impact current drought response measures. The California Department of Water Resources (DWR) is in charge of the SGMA Program and has developed guidelines for local agencies to follow. DWR has also developed a SGMA website to explain the requirements under the Act. Napa County is currently meeting the requirements of the SGMA.

For groundwater basins or Subbasins given a medium or high priority ranking by DWR, SGMA provided an option for local agencies to submit a Basin Analysis Report or other Alternative GSP to DWR by January 1, 2017. The Napa Valley Subbasin (map) is the only basin in Napa County with a priority ranking by DWR that is subject to SGMA at this time.

DWR  completed its evaluation and re-prioritization of all of the groundwater basins across California, which was finalized in January 2019. The Napa Valley Subbasin was reprioritized from a medium to a high priority ranking due primarily to revised projections of future population for the Subbasin, an increased assessment of the total number of wells, and a revised approach to evaluating water quality in the Subbasin. The change from a medium y to a high priority does not affect current requirements for the Napa Valley Subbasin under SGMA. DWR has noted that the Napa Valley Subbasin is being managed sustainably and it is not in overdraft.

Sustainable Groundwater Management Act (SGMA) Requirements

The County and its groundwater consultant have completed work to meet the requirements of SGMA, which was in the form of an Alternative Groundwater Sustainability Plan/Basin Analysis Report, an approved Alternative to a Groundwater Sustainability Plan (GSP). The report, Napa Valley Groundwater Sustainability - Basin Analysis Report for the Napa Valley Subbasin, provides an extensive analysis of the basin and demonstrates it has operated within its sustainable yield and that it is being managed consistent with the goals of SGMA and DWR regulations.

Alternative Groundwater Sustainability Plan

In accordance with SGMA and adopted GSP regulations, Napa County submitted an alternative GSP (Napa Valley Groundwater Sustainability: A Basin Analysis Report for the Napa Valley Subbasin) to DWR on December 16, 2016. On July 17, 2019, DWR sent a notification letter and staff report to Napa County outlining DWR’s preliminary recommendation to not approve the County’s alternative GSP. 

DWR’s staff report did not consider and does not conclude that the Napa Valley Subbasin is, or has been, managed unsustainably. DWR’s preliminary staff recommendation centers on the evaluation that Napa County did not establish and operate the subbasin to thresholds or objective management criteria for a period of at least 10 years prior to the adoption of SGMA. On October 11, 2019, Napa County provided a response to DWR to address their questions and other requested clarifications regarding the alternative GSP.  Please see DWR's SGMA Portal for Alternatives and Reporting for additional information and updates.

A hard-copy of the GSP Alternative is available for review at the Napa County Flood Control and Water Conservation District office, 804 First St., Napa, (707) 259-8600. An electronic copy of the report is available on Napa County’s Watershed Information and Conservation Council (WICC) website.

SGMA requires annual reporting on groundwater conditions and on any actions taken by Napa County to ensure the sustainable management of Napa Valley groundwater resources. The 2017 and 2018 Annual Groundwater Reports are available on The reports describe groundwater conditions in the Napa Valley Subbasin and provide an update on the County’s SGMA implementation efforts through water year 2018, as required by SGMA and DWR. Additionally, the 2017 Annual Report includes an Amendment to the 2016 Alternative GSP/Basin Analysis Report, establishing a Northeast Napa Management Area (PDF). The Amendment complements the management actions in the 2016 Alternative GSP/Basin Analysis Report for the Napa Valley Subbasin and enables continued attainment of the SGMA Sustainability Goals for the Napa Valley Subbasin.

Annual reports developed for SGMA purposes are required to be submitted to DWR by April 1 of each year following adoption of a GSP or Alternative GSP (Regulations Section 356.2). Napa County submitted the 2018 Annual Report to DWR on March 22, 2019 after public notice and presentation at a public meeting of the Board of Supervisors on March 22, 2019.