Sustainable Groundwater Management

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The 2014 Sustainable Groundwater Management Act (SGMA) provides a framework for sustainable management of groundwater resources by local authorities. The act establishes 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 drought response measures. The Department of Water Resources (DWR) is in charge of the SGMA Program and has developed guidelines for local agencies to follow. Napa County is the lead local SGMA implementation agency and 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.

Napa Valley Subbasin

Alternative Groundwater Sustainability Plan (GSP)

Basin Analysis Report for the Napa Valley Groundwater Subbasin

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. That report and supporting documents are available below. 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 July 17, 2019 staff report, it did not consider and does not conclude that the Napa Valley Subbasin is, or has been, managed unsustainably. DWR’s preliminary evaluation of the alternative GSP was 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. Napa County has prepared a response to DWR to address this question and other requested clarifications.

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.

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

The 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 which time 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 in early 2019. Please see DWR's SGMA Portal for Alternatives and Reporting for additional information and updates.

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. Napa County's 2017 and 2018 Annual Groundwater Monitoring Reports are SGMA compliant and available on the WICC's groundwater monitoring page. They describe groundwater conditions in the Napa Valley Subbasin and provide an update on the County’s SGMA implementation efforts through water year 2018. In addition, the 2017 Annual Report includes an Amendment to the 2016 Alternative GSP/Basin Analysis Report, establishing a Northeast Napa Management Area. 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 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 19, 2019.

DWR evaluates and re-prioritizes all of the groundwater basins across California. During the first phase of DWR’s basin re-prioritization (finalized in January 2019) the Napa Valley Subbasin was changed from a medium to a high priority ranking. The increase in priority designation for the Napa Valley Subbasin was 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 compared to the previous prioritization analysis performed in 2014. The change from medium priority to high priority does not affect current requirements for the Napa Valley Subbasin under SGMA.

Alternative GSP/Bain Analysis Report Documents

Final Documents Submitted to DWR:

Final Basin Analysis Report
Final Basin Analysis Report Appendices 1 of 2
Final Basin Analysis Report Appendices 2 of 2
Final Basin Analysis Report Alternative Elements Guide
Final Basin Analysis Report Supervisor Approval and Authorization
Final Basin Analysis Report CEQA NOE
Final Basin Analysis Report MWELO Implementation
Final Basin Analysis Report Well Construction Standards
Final Basin Analysis Report Groundwater Conditions and Monitoring Report 2011

Other Basins and Subbasins in Napa County

Three other groundwater basins located in Napa County (including Pope Valley Basin and Berryessa Valley Basin, and Suisun-Fairfield Valley Basin) remain designated as very low or low priority according to DWR’s re-prioritization published in January 2019.

DWR approved a jurisdictional basin boundary modification for the Napa-Sonoma Lowlands Subbasin in February 2019 based on a request submitted by the Sonoma Valley Groundwater Sustainability Agency. The approved modification aligns the groundwater subbasin boundary with the Napa-Sonoma County line to allow for more efficient implementation of SGMA by local agencies.

On April 30, 2019, DWR announced a new draft re-prioritization for the Napa-Sonoma Lowlands Subbasin that maintains the very low ranking. A public comment period on the draft re-prioritization was open until May 30.

On December 18, 2019, DWR announced completion of a multi-year process to prioritize all 515 groundwater basins in California as part of the Sustainable Groundwater Management Act (SGMA). The final priority ranking retained a very low priority rank for the Lowlands Subbasin. This low rank means the Lowlands Subbasin would is not subject to additional requirements through SGMA. Please see DWR’s basin re-prioritization website for details and updates on their process.

Napa County Groundwater Program Contact

Patrick Lowe, Natural Resources Conservation Manager, (707) 259-5937,