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 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 provides information from shallow and deep aquifer systems. The new wells range in depth from 50 feet to 471 feet below ground surface. The GMWs 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.

Seepage Run Study – October 2021 to August 2022

From 2021 to 2022, with funding from the California Department of Water Resources Proposition 68 grant and on behalf of the GSA, Sonoma Water completed performance of synoptic streamflow measurements (seepage runs) in streams and creeks in the Santa Rosa Plain Subbasin to assist in identifying and mapping interconnected surface waters. The seepage runs were performed over a complete hydrologic year and consisted of six measurement events performed in October 2021, December 2021, February 2022, April 2022, June 2022, and August 2022 across 49 different sites to capture seasonal variations in surface water and groundwater interactions. 

Read more about the study and results in the full report here. 

Outreach to Rural Well Owners

Approximately 5,400 rural well owners in Sonoma County received a survey designed to elicit their concerns and ideas about local groundwater conditions in December 2020. Thank you to the more than 1,000 people – 22% — who returned surveys!

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 analyzed and 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. Survey results were shared with the GSA Board at its February  2021 meeting.

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:
Rural Residential Changes:
Interconnected Surface Water:
Groundwater Dependent Ecosystems:

Community Meeting: Defining Groundwater Sustainability in the Santa Rosa Plain Basin

This community meeting on May 19, 2021 covered an overview of the basin and concerns, the groundwater budget (how much water is coming into the basin and how much water is going out — now and into the future), how to define sustainability locally, and measuring sustainability. 

Community Meeting:  Groundwater Sustainability in Our Basin

This public workshop held on July 29, 2020 was an opportunity for well owners, farmers and others in the Santa Rosa Plain to learn about groundwater in the basin and to help define local, sustainable groundwater management.


Opening Remarks: Sam Magill, Facilitator, CSU Sacramento Consensus and Collaboration Program

Welcome: Chair Lynda Hopkins

The Santa Rosa Plain Groundwater Basin: Marcus Trotta, Hydrogeologist, Sonoma Water
Click here for basin presentation

Defining Groundwater Sustainability: Andy Rogers, GSA Administrator
Click here for sustainability presentation

View the community workshop 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.


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

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




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.

Workshop Notes | Workshop Recording

How Models Can be Used to Determine the Impact of Climate Change on Groundwater Presentation

Sonoma Water Regional Water Resource Climate Adaptation Programs Presentation

The Sustainable Groundwater Management Act and Climate Change Presentation