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.

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.

For medium and high priority groundwater basins/subbasins, a Basin Analysis Report or other Alternative GSP must be submitted to DWR by January 1, 2017. The Napa Valley Subbasin (PDF) is the only basin in Napa County with a medium priority ranking by DWR that is subject to SGMA at this time.

DWR is currently in the process of evaluating and reprioritizing all of the groundwater basins across California. DWR’s basin reprioritization effort is recommending modifying the Napa Valley Subbasin from a medium to a high priority ranking and the Napa-Sonoma Lowlands Subbasin from a very low to medium priority ranking based upon the relative importance of groundwater within each of the basins. DWR is also reviewing a basin boundary modification for the Lowlands Subbasin that was submitted by the Sonoma Valley Groundwater Sustainability Agency. DWR’s reprioritization is still in draft and will not be final until late 2018 or early 2019. Please see DWR’s basin reprioritization website for details and updates on their process.

Alternative Groundwater Sustainability Plan

An Alternative GSP/Basin Analysis Report for the Napa Valley Subbasin was presented to the Board of Supervisors at a Special Meeting on December 13, 2016. At that meeting, the Board approved the report and its submittal to DWR. The Report was submitted to DWR on December 16, 2016. DWR is currently reviewing the Alternative GSP/Basin Analysis Report. Their comments and recommendations are expected by early 2019. Please see DWR's SGMA Portal for Alternatives and Reporting for additional information and updates. A hard-copy of the report 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 Annual Report is available on It describes groundwater conditions in the Napa Valley Subbasin and provides an update on the County’s SGMA implementation efforts through water year 2017, 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 Goal for the Napa Valley Subbasin.

Annual reports developed for SGMA purposes are required to be submitted by April 1 of each year following adoption of a GSP or Alternative GSP (Regulations Section 356.2). Napa County submitted the 2017 Annual Report to DWR on March 23, 2018 after public notice and presentation at a public meeting of the Board of Supervisors on March 20, 2018.