First-ever well water regulations coming to Sonoma County

January 10, 2022

Three local agencies that govern about 8,000 private and public wells will hold public hearings this week on plans to sustain underground water relied on by rural residents, farmers and cities.

The Groundwater Sustainability Plans, mandated by state law, represent California’s first move to regulate and set fees for well water use — a historically unrestricted domain often compared to the “Wild West.”

The plans, endorsed by the Sonoma County Board of Supervisors in November, are up for approval by the Groundwater Sustainability Agencies governing basins underlying the Santa Rosa Plain and the Petaluma and Sonoma valleys.

The three agencies will conduct virtual meetings via Zoom, with Sonoma Valley leading off Monday, Petaluma Valley on Wednesday and Santa Rosa Plain on Thursday.

Each plan assesses the conditions in the basin, analyzes the basin’s sustainability over a 50-year period and identifies projects and actions needed to ensure the basin is sustainable by 2042 and can maintain that status to at least 2072.

Sustainability is defined as the absence of a significant drop in groundwater tables year-to-year.

There are about 5,800 wells in the 80,000-acre Santa Rosa basin, about 1,500 wells in the 44,000-acre Sonoma Valley basin and about 700 wells in the 46,000-acre Petaluma Valley basin.

The three basins, combined, cover about 15% of the county.

The Santa Rosa basin plan “reflects the unique characteristics of the groundwater basin, which includes the county’s largest city, agriculture, rural residents, tribes and important natural resources,” Tom Schwedhelm, a Santa Rosa City Council member and chair of the Santa Rosa sustainability agency, said in a news release.

The plans include a “climate change scenario” that anticipates “several very dry years through 2025; normal and wetter years through 2050; and then a long-term drought after the mid-twenty-first century.”

The forecast provides a “stress test” for groundwater resource planning, said Ann Dubay, administrator for the Petaluma Valley and Sonoma Valley Groundwater Sustainability Agencies.

“We have to project what groundwater looks like out to the 2070s,” she said.

Each agency is governed by board members appointed by agency members, including cities, towns, water and conservation districts, county supervisors and the county water agency.

The plans do not cover the most controversial aspect of groundwater regulation: fees that will be charged to well water users.

A fee consultant will meet in February with directors of the three agencies to discuss options for the fees that will be implemented in mid-2022.

“We have no idea what these fees will look like,” Dubay said last week.

The first five-year costs of implementing the Petaluma Valley and Santa Rosa Plain plans are estimated at $1.1 million annually, not including capital costs.

In Sonoma Valley, the five-year implementation costs are about $1.2 million annually, plus an estimated $8.6 million in capital costs.

Following approval by the local agency boards of directors, the sustainability plans will be submitted to the California Department of Water Resources for final approval.

Implementation of the plans must begin in 2022 while the plans are still under review.

Groundwater sustainability agency hearing schedule

Sonoma County’s three groundwater sustainabilty agencies are holding public hearings this week on their state-mandated plans.

Sonoma Valley, 4 p.m. with hearing beginning no earlier than 4:15 p.m. via Zoom at

Go to for more information.

Petaluma Valley, 5:30 p.m. Wednesday with hearing beginning no earlier than 5:45 p.m. via Zoom at

Go to for more information.

Santa Rosa Plain, 1 p.m. Thursday with hearing beginning no earlier than 1:15 p.m. via Zoom at

Go to for more information.