Sonoma County backs well water regulations, advancing new era of groundwater oversight

Sonoma County signed off on plans to protect groundwater supplies in three critical basins serving rural residents, farmers and cities.|

Groundwater sustainability plans in Sonoma County

To read more about plans for the county’s 3 major groundwater basins, visit

Hailed as a complex and historic step, Sonoma County supervisors on Tuesday unanimously endorsed plans to guide use and governance of groundwater relied on by rural residents, farmers and cities.

The plans, required by a 2014 state law crafted amid California’s past drought, will eventually include well water use fees in three basins underlying the Santa Rosa Plain and Sonoma and Petaluma valleys.

The plans, four years in the works and due for submission to the state Department of Water Resources in January, are “extraordinarily complex, politically charged and technically nuanced,” board Chair Lynda Hopkins said.

“This is a very big deal,” she said, calling it the “first time ever the state of California regulated groundwater,” a resource that has been handled like the “Wild West for all this time.”

The vote came with just a few remarks by supervisors and no public comments or questions. Official approval of the plans is still to come from the Groundwater Sustainability Agencies in charge of each basin, a step set for December.

“I wasn’t sure that we’d ever get to this point, but we did,” Supervisor Susan Gorin said.

The plans are blueprints for use and governance over the next three decades. One critical part of their enforcement — the fees that will be charged to well water users — has not been decided.

“Eventually we will have to set those fees,” said Supervisor David Rabbitt, the board’s senior incumbent. The fee structure needs to credit areas “that are putting more water down into the ground,” he said.

A county report said the state law “mandated that groundwater resources be sustainably managed to ensure that water will be available today and into the future for all beneficial users, including flora and fauna, municipal and domestic, agricultural, and business users.”

Cities, even those that primarily draw their drinking water from the Russian River, benefit from groundwater, Rabbitt said, calling it “a shared resource that belongs to all of us.”

Each of the three basins is governed by a groundwater sustainability agency with a board made up of elected or appointed members from eligible agencies, including a representative from both the county and Sonoma Water, the agency that delivers Russian River water to more than 600,000 Sonoma and Marin county residents.

The agencies must achieve sustainability — no significant drop in groundwater tables year-to-year — by 2042 and maintain sustainability to at least 2072.

“Compared to the critically over-drafted groundwater basins in the Central and San Joaquin valleys, the three Sonoma County basins are in relatively good shape — but still face challenges,” said a staff report from Sonoma Water and Permit Sonoma, the county’s planning and building department.

The report cited “gaps in data” in all three basins, especially regarding “the relationship between groundwater pumping and the depletion of connected creeks and streams.”

The plans — described by Jay Jasperse, chief engineer and director of groundwater management at Sonoma Water, as “very dense content documents” — find groundwater levels and storage in Petaluma Valley “appear to be stable.”

Data on seawater intrusion and depletion of surface water is limited “but there is currently no evidence of problems,” the staff report said.

Conditions in the Santa Rosa Plain are “generally sustainable” but require future projects and management to maintain sustainability through 2070. Groundwater storage is declining by about 2,100 acre feet a year.

In Sonoma Valley, groundwater storage is declining by about 900 acre feet a year and will continue to decline without projects and management actions, such as groundwater banking, recycled water and efficient water use, the report said. (An acre foot equals 326,000 gallons, enough to cover a football field with a foot of water.)

“All three plans focus on filling data gaps so better information will be available on basin conditions moving forward, it said.

The first five-year costs of implementing the plans in Petaluma Valley and the Santa Rosa Plain are estimated at $1.1 million annually, not including capital costs for projects such as recycled water use.

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

The Petaluma Valley and Sonoma Valley groundwater agencies are currently funded by member agencies, including Sonoma Water and the county, under agreements that end in June 2022.

The Santa Rosa Plain agency is funded by groundwater user fees paid by Santa Rosa, Rohnert Park, Cotati, Sebastopol, Windsor and Sonoma Water, augmented by separate fees paid by Sonoma Water and the county.

The three agencies have each received about $2.2 million in grants and technical support from the Department of Water Resources to offset costs of plan development and installation of monitoring wells and are expected to seek future funding for plan implementation.

You can reach Staff Writer Guy Kovner at 707-521-5457 or On Twitter @guykovner.

Editor’s note: This article has been updated to clarify that the Board of Supervisors endorsed the groundwater management plan, and that it lacks the authority to approve the plan.

Groundwater sustainability plans in Sonoma County

To read more about plans for the county’s 3 major groundwater basins, visit

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