Periodic Evaluation of the Groundwater Sustainability Plan

The Sonoma Valley Groundwater Sustainability Agency is currently conducting a Periodic Evaluation of the Groundwater Sustainability Plan (GSP), as required by the State of California under the Sustainable Groundwater Management Act (SGMA). The GSP for the Sonoma Valley Subbasin was submitted to the California Department of Water Resources (DWR) in Jan. 2022 and approved by DWR on Jan. 26, 2023. The GSP establishes a standard for sustainability of groundwater management and use and determines how the basin will achieve this standard by 2042.

Periodic Evaluations are required every five years to ensure that Groundwater Sustainability Plans remain current, effective, and aligned with the best available data and regulatory guidance. Periodic Evaluations also provide the foundation for future GSP amendments, if needed.

Draft Periodic Evaluation Report: Key Highlights

New information collected with the support of funding from a DWR grant, helped implement actions and fill important data gaps identified in the GSP. Some of the key highlights of the Periodic Evaluation are:

  • New information collected with DWR grant funding filled important data gaps identified in the GSP
  • DWR Recommended Corrective Actions addressed
  • Monitoring networks were improved with new well installations and voluntary monitoring
  • Review of groundwater data over the past 5 years indicates undesirable results for groundwater levels and groundwater storage have occurred and are ongoing
  • Undesirable results for water quality, interconnected surface water, land surface subsidence, and seawater intrusion have not occurred
  • Progress has been made on projects and management actions through planning, pilot studies and initial implementation

The Draft Periodic Evaluation Report concludes that:

GSP Amendment is needed to address undesirable results. Specific areas of the GSP that are anticipated to be updated or revised through the Amendment are:

  • Designation of the El Verano and Eastside Groundwater Sustainability Priority Areas as management areas within the Subbasin
  • Modifications to the approach to monitor for total dissolved solids for the Water Quality Monitoring Network
  • Potential modifications to sustainable management criteria for seawater intrusion
  • Incorporation of a demand management plan and financial analysis resulting in reprioritization and focus for projects and management actions

Development of a Plan Amendment is underway and is expected to be submitted in spring of 2027.

Documents Available for Review

the cover of a report for the periodic evaluation in sonoma valley with a photo of a vineyard

Timeline and Opportunities for Public Input:

Public participation is a key component of the Periodic Evaluation process. A 30-day comment period as well as two public meetings (Advisory Committee and Board Meetings) provide the opportunity for stakeholders to provide comments on the report.

  • September 9 – October 9: The public is invited to submit comments via email to info@sonomavalleygroundwater.org
  • Tuesday, September 15, 3:00-5:30 PM: Sonoma Valley GSA Advisory Committee Meeting, Valley of the Moon Water District, Board Room, 19039 Bay Street, Sonoma Opportunity for public comment
  • October: GSA will make revisions based on comments
  • Monday, October 26, 4:00 – 6:00 PM: Discuss revisions at the GSA Board of Directors Meeting, Valley of the Moon Water District, Board Room, 19039 Bay Street, Sonoma Opportunity for public comment
  • Tuesday, December 15, 3:00-5:30 PM: Discuss revisions at the Sonoma Valley GSA Advisory Committee Meeting, Valley of the Moon Water District, Board Room, 19039 Bay Street, Sonoma Opportunity for public comment
  • Monday, January 25, 4:00 – 6:00 PM: Present revised draft at the GSA Board of Directors Meeting, Valley of the Moon Water District, Board Room, 19039 Bay Street, Sonoma Opportunity for public comment
  • Following the January 25 board meeting: Submit final Periodic Evaluation Report to the California Department of Water Resources.

For any questions regarding the Sonoma Valley GSA Periodic Evaluation and the public comment process, please email: info@sonomavalleygroundwater.org