GSA Activities

Monitoring Well Installation

In 2022, with funding from the California Department of Water Resources Proposition 68 grant, three new multilevel groundwater monitoring wells (GMWs) were constructed by the GSA. These GMWs expand on the existing monitoring network, filling critical data gaps regarding groundwater levels, saltwater intrusion, and interconnected surface water, as the GSA works to track progress toward achieving the Groundwater Sustainability Plan goal of sustainable groundwater management by 2040.

Data collected will provide information from shallow and deep aquifer systems. The new wells range in depth from 110 feet  to 465 feet below ground surface. The GMWs will help track seasonal fluctuations in groundwater levels and quantify annual changes in water budget components. The monitoring wells have been instrumented with dataloggers to remotely collect water-level and temperature data on an hourly basis.

Read the full report on the new monitoring wells here.

Geophysical Investigations: WalkTEM, ERT, & AEM Surveys

In 2022, the GSA completed a geophysical investigation of portions of the basin to further characterize the basin and refine the basin hydrogeologic models for Groundwater Sustainability Plan implementation. Ground-based transient electromagnetic (WalkTEM) and Electrical Resistivity Tomography (ERT) geophysical surveys were performed and correlated with airborne electromagnetic (AEM) and borehole data from the DWR Statewide AEM Project. These surveys will be used to help fill data gaps related to saltwater intrusion and water quality in the southern portions of the basin. This project was completed with funding from the California Department of Water Resources Proposition 68 grant.

Read the full report below:

Outreach to Rural Well Owners Underway

Approximately 9,500 rural well owners in Sonoma County received surveys designed to elicit their concerns and ideas about local groundwater conditions. The purpose of the survey was to raise awareness about local groundwater management and to solicit feedback from well owners regarding any concerns they may have about groundwater in the basin. The survey results were used as the basis for focus groups to provide an opportunity for more in-depth discussions of issues and ideas for improving groundwater conditions.

This joint project of the county’s three Groundwater Sustainability Agencies (GSAs) was the first step in an engagement project designed to educate and receive feedback from well owners in the Petaluma Valley, Santa Rosa Plain and Sonoma Valley groundwater basins.

Read the full press release here.

Practitioners Work Groups

The three Sonoma County GSAs received funding from California Department of Water Resources through the California Drought, Water, Parks, Climate, Coastal Protection, and Outdoor Access for All Act of 2018 (Proposition 68) to facilitate four work groups comprised of technical subject experts. The work groups were formed to help with the development of the Groundwater Sustainability Plans in four areas:

  • Rural residential population projections;
  • Agricultural water demand projections;
  • Groundwater-dependent ecosystems; and
  • Interconnected surface water depletion.

The work groups began meeting in summer 2020 and were facilitated by a neutral facilitator from the Consensus and Collaboration Program with CSU Sacramento. The work group products were shared with the Board  and Advisory Committees of the GSAs, and were used to develop the water budgets and Sustainable Management Criteria for Interconnected Surface Water.

Meeting materials are below:

 Agricultural Water Demands:

Ag Working Group Meeting slides (overview), Summer 2020
Land-Use Surveys, Fall 2020
Summary Report, 1-4-2021
Agricultural Expansion and Contraction Model, 1-20-2021

Rural Residential Changes:

Summary Report

Interconnected Surface Water:

Draft Meeting Summary, 10-7-2020
Presentation, Meeting 1
Draft Meeting Summary, 12-11-2020
Presentation, Meeting 2
Presentation, Meeting 3
Surface Water Depletion Modeling presentation
Santa Rosa Plain data, monitoring wells near streams

Groundwater Dependent Ecosystems:

Draft Meeting Summary, 7-7-2020
Presentation, Meeting 1
Draft Meeting Summary, 11-19-2020
Presentation, Meeting 3

Community Workshop: Sustainable Groundwater in Our Basin 

Do you get your water from a well? Do you worry about your water quality or water levels? Are you concerned about the costs of water in the future?

Agenda | Workshop Recording 

Part 1 includes: Opening Remarks , Welcome, The Sonoma Valley Groundwater Basin and Questions about the basin

Part 2 includes: Defining Groundwater Sustainability and Questions about sustainability

Presentations are available here:


Recharging Groundwater Basins:  Facts, Myths, Projects and Possibilities Workshop

This public workshop held on December 11, focused on how groundwater can be recharged to help better manage and sustain local aquifers. 

Presentations included:

  • Recharge: What is it? How does it work? What are the different types of recharge? | Marcus Trotta, Sonoma Water
  • California’s Flood-MAR (Managed Aquifer Recharge) project: What is it? Where is it happening? How does it work? | Kamyar Guivetchi, California Department of Water Resources
  • Local recharge efforts: What farmers are doing in Sonoma County to enhance recharge | Dr. Phil Bachand, Bachand & Associates

Workshop Agenda
ALL Workshop Presentations
Recharge Workshop Notes
Increased Shallow Groundwater Levels from RAU
FloodMAR Research and Data Development
Implementation Factors FloodMAR
UCCE Groundwater RechargeFloodMAR fact sheet


Climate Change Workshop

On May 22, the three Groundwater Sustainability Agencies held a public workshop “How a changing climate could affect our groundwater basins – and what we’re doing about it.” The focus of this public workshop was on how climate change must be addressed in the Groundwater Sustainability Plans.