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File #: 21-1305    Version: 1
Type: Public Hearing Status: Passed
File created: 11/23/2021 In control: Board of Supervisors
On agenda: 12/7/2021 Final action:
Title: PUBLIC HEARING 1:45 PM - 30 Minutes Director of Planning, Building and Environmental Services to present the Draft Napa County Groundwater Sustainability Plan. (CONTINUED FROM NOVEMBER 16, 2021)
Attachments: 1. Letter of Transmittal, 2. Executive Summary Abstract, 3. Executive Summary, 4. Executive Summary_Spanish, 5. Table 5-18, 6. Table 11-3, 7. Table 12-3, 8. PowerPoint (added after meeting)


TO:                     Board of Supervisors

FROM:                     David Morrison - Director of Planning, Building and Environmental Services

REPORT BY:                     David Morrison - Director of Planning, Building and Environmental Services

SUBJECT:                     Presentation of Napa County Groundwater Sustainability Plan




PUBLIC HEARING 1:45 PM - 30 Minutes

Director of Planning, Building and Environmental Services to present the Draft Napa County Groundwater Sustainability Plan.





The Sustainable Groundwater Management Act (SGMA) of 2014 requires the implementation of groundwater sustainability planning and management for groundwater basins or subbasins that the California Department of Water Resources (DWR) has designated as medium or high priority.  Napa County contains one high priority basin, the Napa Valley Subbasin (Subbasin) for which a groundwater sustainability agency (GSA) was formed in December 2019.  All medium and high priority subbasins within California must adopt Groundwater Sustainability Plans (GSPs) by January 31, 2022.

A 25-member Groundwater Sustainability Plan Advisory Committee (GSPAC) was formed in June 2020 to advise the Napa County GSA Board of Directors on the preparation of the GSP with policies and recommendations to manage and ensure the long-term protection and availability of groundwater resources within the Subbasin. The GSPAC met 21 times over the course of 18 months and during its final meeting on November 16, 2021, a supermajority of committee members voted to recommend the NCGSA adopt the GSP. 

GSPAC bylaws, which required that the Committee make their recommendation to the Napa County Groundwater Sustainability Agency (NCGSA) by November 1, 2021, were subsequently amended by the NCGSA on October 19, 2021, to extend the deadline to November 19, 2021. The GSP was transmitted to the NCGSA along with a Transmittal Letter co-authored by GSPAC Chair David Graves and Vice Chair Alan Galbraith on November 19, 2021.


1.  Chair introduces item
2.  Presentation by staff
3.  Public comments
4.  Motion and second to consider adoption of the GSP.



Is there a Fiscal Impact?


Is it currently budgeted?


Where is it budgeted?

Org 2720000

Is it Mandatory or Discretionary?


Is the general fund affected?


Future fiscal impact:

Analysis of future impact is pending

Consequences if not approved:

County would be out of compliance with the Sustainable Groundwater Management Act (SGMA)

County Strategic Plan pillar addressed:

Vibrant and Sustainable Environment



ENVIRONMENTAL DETERMINATION: The proposed action is not a project as defined by 14 California Code of Regulations 15378 (State CEQA Guidelines) and therefore CEQA is not applicable.



Brief History of Groundwater Management

In many ways, the adoption of a Groundwater Sustainability Plan (GSP) is another step in the continuum of proactive groundwater management by Napa County.  From groundwater data collected since the 1960s to the first Groundwater Ordinance adopted in 1999, Napa County has managed environmental resources through land use controls and other regulations for over five decades. Although the terminology was different, the Board of Supervisors (BOS) has understood since the 1960s that the “sustainable yield” of groundwater should not be exceeded (Draft GSP Section 3.3.1). 

Efforts over the decades have included:

                     Groundwater data collection (since the 1960s)

                     Establishment of the Napa Valley Agricultural Preserve (1966)

                     Napa Valley safe yield analysis and permitting actions, including the Water Availability Analysis policy and guidance, to avoid undesirable results (first implemented in 1991 and later revised in 2003, 2007, and 2015)

                     A collaborative effort to develop the Napa River Watershed Owner’s Manual (1992)

                     Napa County BOS adopted Ordinance No. 1162 with the intent to regulate the extraction and use and promote the preservation of the County’s groundwater resources (first adopted in 1999)

                     Formation of the Watershed Information and Conservation Council (2002)

                     Private-public partnerships to restore watershed function and aquatic habitat, including the Rutherford Reach Restoration Project (2002) and Oakville to Oak Knoll Reach Restoration project (in progress)

                     Groundwater Resources Advisory Committee (2011-2014) and work to enhance groundwater and surface water monitoring and advance hydrogeologic studies

                     Additional efforts during the past decade directed towards sustainable groundwater management including mapping groundwater dependent ecosystems, water budget analyses, and estimating the sustainable yield for the Napa Valley Subbasin (since 2009)

                     Basin Analysis Report for the Napa Valley Subbasin, an Alternative submittal per the requirements of Water Code Section 10733.6 (b)(3) (2016)

                     Northeast Napa Management Area (established in 2018)

                     Current efforts underway by the Groundwater Sustainability Plan Advisory Committee (GSPAC) to advise the Napa County Groundwater Sustainability Agency (GSA) on the preparation of a GSP for the Napa Valley Subbasin

                     Annual Reports beginning in 2014 and submitted to DWR since 2017

While development of the GSP was specifically mandated by the Sustainable Groundwater Management Act, it is truly the outcome of work that commenced many years prior to SGMA’s passage. 

Sustainable Groundwater Management Act

In September 2014, Governor Jerry Brown signed the Sustainable Groundwater Management Act (SGMA), a three-bill legislative package now codified in Section 10720 et seq. of the California Water Code. Effective in California on January 1, 2015, SGMA provides a framework for the sustainable management of groundwater resources.

SGMA encourages groundwater management at the local level. Local agencies form GSAs to develop and implement GSPs to guide the sustainable management of state-defined groundwater basins. The NCGSA was created in December 2019 to manage groundwater resources consistent with the SGMA for the Napa Valley Subbasin.

Sustainability Framework

SGMA provides a specific planning framework, including definitions related to sustainable groundwater management and timelines for achieving sustainable conditions. The NCGSA must define the Subbasin sustainability goal and achieve the goal within 20 years of GSP implementation. Achieving the sustainability goal means avoiding significant and unreasonable adverse effects related to groundwater conditions (i.e., undesirable results) for six sustainability indicators:
                     Chronic lowering of groundwater levels
                     Reduction of groundwater storage
                     Seawater intrusion
                     Water quality degradation
                     Land subsidence
                     Depletion of interconnected surface water

Groundwater Sustainability Plan Advisory Committee

The GSPAC was formed in June 2020 to advise the NCGSA Board of Directors on the preparation of the GSP with policies and recommendations to manage and ensure the long-term protection and availability of groundwater resources within the Napa Valley Subbasin. The GSPAC is comprised of 25 geographically diverse members representing beneficial uses and users for a wide array of community, economic, agricultural, and environmental interests within the Subbasin. GSPAC members provided focused input on recommendations during GSP development and guided the development of the Subbasin sustainable management criteria and overall GSP development.

The GSPAC met 21 times over the course of 18 months and during its final meeting on November 16, 2021, 80 percent of committee members voted to recommend the NCGSA adopt the GSP. 

Groundwater Sustainability Plan

The purpose of the GSP is to provide a detailed road map for the Napa Valley Subbasin to achieve the goal within 20 years and maintain long-term sustainability indefinitely. The core GSP is over 1,000 pages accompanied by over 4,000 pages of appendices. The complete GSP can be found online here: 

For the convenience of the NCGSA and the public, an Abstract and Executive Summary (in English and Spanish) were produced and are provided with this staff report.  Two (2) bound and printed copies of the GSP (including the Spanish language version of the Executive Summary) have been produced for the convenience of any members of the public who prefer to review a hardcopy.  They can be found at the following locations during regular business hours:  Napa County Library, Reference Desk, 500 Coombs St. and Napa County Administration Building, Department of Planning, Building and Environmental Services, 1195 Third Street, 2nd Floor, Napa. 

The GSP development process primarily included:
                     Characterizing groundwater conditions, identifying data gaps and levels of uncertainty, and developing tools to improve data collection;
                     Developing sustainable yield estimates and water budgets;
                     Defining sustainable management criteria including quantitative measurable objectives, minimum thresholds, and undesirable results; and
                     Establishing projects and management actions to achieve and maintain sustainability and avoid undesirable results.

The GSP must consider the interests of all beneficial uses and users of groundwater, and encourage the involvement of diverse social, cultural, and economic interests within the Subbasin during GSP preparation and implementation.

Technical Work Group

The GSPAC unanimously adopted a recommendation that the NCGSA appoint a Technical Work Group (TWG) with responsibility to advise the NCGSA on matters relating to GSP implementation, including addressing data gaps and strong and timely adaptive management to achieve the Subbasin sustainability goal. Following NCGSA adoption of the GSP, staff will initiate steps to identify and vet potential TWG candidates. For more information, see GSP, Section 11.8.2.

GSP Sustainable Management Criteria

Much of the work of the GSPAC involved defining sustainable management criteria for the six sustainability indicators. 
The conditions that constitute undesirable results were defined qualitatively and quantitatively for each of the six indicators. For each indicator, minimum thresholds were established, consisting of numeric values at representative monitoring sites in the Subbasin.  Undesirable results, i.e., the conditions we want to avoid, are created when these values are exceeded. Triggers have also been established for each of the sustainability indicators to warn of conditions that may lead to potential undesirable results. The TWG has a critical role in reviewing monitoring data, considering corresponding sustainable management criteria, and providing recommendations to the NCGSA for timely implementation of projects and management actions as needed whenever triggers are exceeded to avoid undesirable results from materializing.  By implementing and updating these measurable objectives, the GSP will achieve the sustainability goal within 20 years and will continue to protect the Subbasin beyond the 50-year planning horizon.

Table 11-3 summarizes minimum thresholds, triggers, and undesirable results along with potential response actions including projects and/or management actions, which could be taken as needed to avoid undesirable results. 

GSP Monitoring Networks and Recommended Network Additions

Monitoring networks are designed to promote the collection of data of sufficient quality, frequency, and distribution to characterize groundwater and related surface water conditions in the Subbasin and evaluate changing conditions that occur during GSP implementation.

Existing and planned monitoring sites for the following nine GSP   networks include:

                     Groundwater level monitoring: 56 wells (16 additional planned)
                     Groundwater quality monitoring: 37 wells (16 additional planned)
                     Groundwater storage change monitoring: 26 sites (10 additional planned)
                     Seawater intrusion monitoring: 16 wells (2 additional planned) 
                     Surface water quality monitoring: 7 sites (4 additional planned)
                     Stream stage and stream discharge monitoring: 20 sites (10 existing sites planned to be upgraded)
                     Interconnected surface water monitoring: 16 wells (8 additional planned)
                     Groundwater dependent ecosystem monitoring: 15 wells (8 additional planned)
                     Land surface elevation monitoring: 8 land surface elevation benchmark sites and 15 well sites

For more information see GSP Sections 5 and 12 and Tables 5-18 and 12-3.

GSP Implementation

As noted in the Transmittal Letter from the GSPAC Chair and Vice Chair, timely implementation of the GSP is critical and was a matter of great importance to the GSPAC. 

Table 12-3 of the GSP summarizes recommended implementation actions grouped into three general categories:  Projects and Management Actions (PMAs), Monitoring Subbasin Conditions, and Model and Water Budget Refinement. The data gap or objective to be addressed (including uncertainty) is also summarized for each recommended action. 

PMAs in particular are one of the most important parts of the GSP and include planned actions such as vineyard and winery water conservation, managed aquifer recharge, expanded recycled water use, pumping reductions and changes to the groundwater ordinance and new well permit conditions.

Next Steps

The GSA must submit an adopted GSP to DWR by January 31, 2022. The GSP submittal includes the GSP document, all GSP appendices, copies of all references, and data used for GSP development. The entire GSP submittal will be posted to DWR’s SGMA Portal website (, where DWR will provide a public comment period lasting at least 60 days. The California Water Code requires that DWR conduct a review of all GSA-approved GSPs within two years of submittal.

The GSP is a living, dynamic document that will guide expanded monitoring, including efforts to identify and fill data gaps, and projects and management actions as needed to achieve the Napa Valley Subbasin sustainability goal. State GSP Regulations require that GSPs be updated at least every five years or sooner, if warranted by new information that becomes available during GSP implementation.

Upon GSP adoption, NCGSA staff would commence the process of forming a Technical Work Group, consisting of members with appropriate qualifications, to assume the responsibility and the timely opportunity to advise the NCGSA. The TWG will be involved with implementation of the GSP, and include, among other things, a focus on closing data gaps and adaptive management of the groundwater resource. Adaptive management approaches will be used during GSP implementation, including forward looking monitoring, water budget refinements, reporting and outreach, evaluation of sustainable management criteria, and assessments of the effectiveness of projects and management actions.

Steps to initiate the development of several workplans identified in GSP Section 11 and shown in Table 12-3 will be initiated following GSP adoption. The next Napa Valley Subbasin Annual Report is due to DWR by April 1, 2022.

Stakeholder input will continue to be an essential component of informed analysis of new data, approaches, and recommendations to communicate to the NCGSA for resource management actions to ensure sustainability.