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Sonoma County Well Permits and Groundwater Rules for Vineyards

By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.

A new or replacement agricultural well in unincorporated Sonoma County needs a permit from Permit Sonoma under the well ordinance in County Code Chapter 25B, as amended in 2023, and most permits are ministerial, meaning staff issue them without a discretionary review, if the well fits one of the ordinance’s ministerial classes. Wells inside the county’s Public Trust Review Area that would push a site’s groundwater use above 2 acre-feet a year get discretionary review, and agricultural sites using more than 2 acre-feet must follow conservation rules that can cap vineyard irrigation. In August 2026 the Court of Appeal upheld the county’s public trust analysis but held that the county had not shown its CEQA exemptions applied, and sent the case back to the trial court. Permitting rules could change again while that plays out, so check current status with Permit Sonoma before you rely on a new well.

Groundwater is also managed basin by basin. On the Santa Rosa Plain, in the Sonoma Valley and in the Petaluma Valley, a groundwater sustainability agency charges a per-acre-foot fee on the tax bill and can, in time, restrict larger pumpers. This guide explains both layers for buyers and owners whose plans depend on well water, and how to price that risk into an offer. It sits within our vineyard and winery property guides.

Who regulates a vineyard well in Sonoma County?

Two different public bodies matter, and they do different things.

Layer	Who	What it controls
Well permits	Permit Sonoma (County of Sonoma)	Permits to drill, replace or destroy a well; public trust review; conservation, metering and reporting conditions
Basin management under SGMA	Santa Rosa Plain, Sonoma Valley and Petaluma Valley groundwater sustainability agencies	Groundwater sustainability plans, annual fees, water-use reporting, and possible future limits on larger pumpers
Surface water	State Water Resources Control Board	Diversions from streams and springs, which the well ordinance does not cover

A vineyard can face all three at once: a county well permit, a basin fee, and a separate surface water right for a pond or creek diversion. Our guide to California water rights for vineyards covers the surface water side.

What the 2023 well ordinance requires

The Board of Supervisors held hearings on April 4, 2023, gave final approval on April 18, 2023, and the amendments took effect May 18, 2023. The county’s staff summary describes a two-track system.

The Public Trust Review Area

The county mapped a Public Trust Review Area of about 313 square miles, roughly 18% of the county by the staff summary’s count (the 2026 appellate opinion says 19%), where streamflow that supports coho salmon and steelhead is sensitive to groundwater pumping. It is made of 100-, 250- or 750-foot stream buffers in medium-risk areas and whole subwatersheds in high-risk areas. As adopted, it left out land next to the Russian River mainstem and Dry Creek, whose flows are regulated by reservoir releases, though the summary notes that exclusion could be revisited.

Ministerial wells

Outside the review area, permits are ministerial. Inside it, the county’s staff summary lists six classes of well that are still ministerial:

Injection wells
Public water wells with completed CEQA review
Wells for surface water diversions regulated by the State Water Board
Low water use wells, where the parcel uses 2.0 acre-feet a year or less
Existing use wells, with no increase over the site’s use when the ordinance was adopted
Net zero wells, with no net increase in groundwater use

Discretionary review

A new water supply well in the review area that fits none of those classes gets discretionary review. Permit Sonoma says a new well that raises total site groundwater use above 2 acre-feet a year can be issued only if staff find in writing that it will not adversely affect public trust resources, and the review carries an at-cost deposit of $5,568. The staff summary expected only about 5% of permits to fall into this track, with the county doing the impact analysis at watershed scale and the project subject to CEQA.

Irrigation limits, metering and reporting for agricultural wells

The conservation rules come in two levels. Level 1 applies to all water wells except public and injection wells, and covers items such as a leak and conservation audit, efficient fixtures, the county’s water-efficient landscape rules and a 2,500-square-foot cap on existing lawns.

Level 2 applies to existing use and net zero wells. For agricultural sites using more than 2.0 acre-feet a year, the staff summary lists these requirements:

An agricultural conservation plan covering irrigation design, scheduling, maintenance and soil or plant stress monitoring; enrollment in a certified program may satisfy it.
A frost protection plan, unless the site does not use water for frost protection.
A cap on vineyard and orchard growing-season groundwater use at pre-existing levels, based on metered data or an irrigation analysis averaging three to five years. Without data, the default limit is 0.6 acre-feet per acre per year.

Most new non-residential and mixed-use wells must be metered, with monthly readings reported to the county once a year. Sites using more than 5.0 acre-feet a year also report monthly water levels and an annual conservation report. Existing wells do not need meters, and a single residential user at or below 2.0 acre-feet is exempt.

Two other changes catch owners by surprise. The ordinance ended emergency drilling without county review, replacing it with expedited review. And when a well is replaced, the old well must be destroyed within 90 days after the replacement is completed.

The court case: where well permitting stands in October 2026

Russian Riverkeeper and California Coastkeeper Alliance challenged the 2023 amendments in Sonoma County Superior Court in May 2023, arguing that they violated the public trust doctrine and did not qualify for the CEQA exemptions the county used.

October 30, 2024: The trial court ruled for the groups on both claims. Its judgment set aside the 2023 amendments, rescinded the county’s CEQA exemption, and suspended non-emergency well permits until the county complied with the public trust doctrine; a writ of mandate followed on November 15, 2024.
December 17, 2024: The court order served on the county required it to suspend all non-emergency water well permitting. The county said this also blocked replacement wells for homes, fire protection and agriculture.
March 27, 2025: The First District Court of Appeal granted the county a temporary stay, so Permit Sonoma could keep issuing non-emergency permits during the appeal.
August 4, 2026: The First District Court of Appeal, Division Two (No. A172760, certified for publication as Russian Riverkeeper v. County of Sonoma, 122 Cal.App.5th 382) affirmed the judgment in part and reversed it in part. It agreed that counties share responsibility for the public trust when permitting wells, but held the groups had not shown the county’s public trust analysis was arbitrary, and reversed that part of the ruling. It affirmed the CEQA ruling: the county had not offered substantial evidence that the Class 7 or Class 8 categorical exemptions or the “common sense” exemption applied, noting among other things that about 95% of applications would remain subject to ministerial review.

The court remanded the case and directed the trial court to vacate its October 2024 judgment and November 2024 writ and enter a new judgment that denies the groups’ public trust claim. In its words, it expressed “no opinion as to the manner in which CEQA should be complied with or whether any moratorium or intervening measures concerning non-emergency well permits are appropriate.”

The opinion does not say what happens to the amendments while the county addresses CEQA; that is left to the trial court and the county. The plaintiffs say the county must now prepare environmental review of the ordinance, including its effects on salmon and steelhead in the Russian River watershed.

When we checked on October 24, 2026, Permit Sonoma’s well ordinance page had not been updated for the August ruling. It still pointed to the March 2025 stay as the reason non-emergency permits can be issued, said litigation is ongoing, and said the county will alert the public if the stay is modified or lifted.

We could not confirm from public sources whether the trial court has yet entered the new judgment. Until it does and the county responds, treat permitting terms as unsettled, and confirm with Permit Sonoma, in writing if you can, that permits are being issued and on what terms before you rely on a new well.

The three groundwater sustainability agencies

Under the Sustainable Groundwater Management Act, the state’s Department of Water Resources rates the Santa Rosa Plain, Sonoma Valley and Petaluma Valley basins as medium priority; the county’s other 11 basins and subbasins are low or very low priority. Each basin has its own agency, formed in June 2017, and DWR approved each agency’s 20-year groundwater sustainability plan on January 26, 2023. The Sonoma Valley plan sets 2042 as the date to reach sustainability. The Santa Rosa Plain agency took public comment on a draft periodic evaluation of its plan from July 13 to August 17, 2026, and the other two agencies also have draft evaluations out for review.

Groundwater sustainability fees for 2026-2027

Agency	Adopted rate per acre-foot	What non-municipal users pay
Santa Rosa Plain GSA	$46.04 (adopted June 11, 2026)	$46.04
Sonoma Valley GSA	$147.31 (adopted June 22, 2026)	$46.04, after a county contribution
Petaluma Valley GSA	$333.12 (adopted June 25, 2026)	$46.04, after a county contribution

The County of Sonoma has committed funds so non-municipal users in all three basins pay the Santa Rosa Plain rate; the agencies describe that commitment as running two years, subject to annual county budget approval. Fees are billed on the parcel owner’s property tax bill. Customers of a city, water district or water company are not billed directly, although the utility may pass the cost on.

The agencies estimate use by type rather than meter it. A rural home with a garden and landscaping is estimated at 0.5 acre-feet a year, or $23.02. Agricultural fees depend on the agency’s estimate for that parcel, which an owner can view and correct through the agencies’ GUIDE survey; to dispute a bill you generally pay first, then appeal.

Could a GSA limit pumping?

State law treats someone who pumps 2 acre-feet or less a year for domestic purposes as a “de minimis extractor,” and the Santa Rosa Plain agency says SGMA does not let it meter those domestic wells. The same agency says a plan could limit pumping by individual well owners who pump more than 2 acre-feet a year. No allocations are in place in these basins today, but a vineyard is exactly the kind of user any future limits would reach.

How to underwrite a vineyard that depends on a new well

If the price you are paying assumes new plantings, a winery or a tasting room supplied by a well that does not yet exist, treat water as a condition of the deal, not a detail for later.

Map the parcel. Check whether it lies in the Public Trust Review Area and which basin, if any, it is in, using the county and GSA maps.
Document existing use. Ask for meter records, irrigation logs and the parcel’s GUIDE data. Under the existing use and net zero classes, and under the vineyard irrigation cap, the site’s historical use is what you inherit.
Get the permit history. Pull the well permits, well completion reports and any conditions from Permit Sonoma. Our Sonoma County wells and septic guide lists what to request.
Test the existing wells. Have a licensed professional run a dry-season yield test and water-quality tests, and look at pump age and storage.
Talk to Permit Sonoma before you commit. Confirm the ministerial class you would apply under, or the scope and timing of discretionary review, and the current status of permitting after the court ruling.
Write the contingency to match. Allow enough contingency time for permit answers, or price the land on the water you can document today.

An illustrative example, not a forecast: a buyer plans 20 acres of new vines on a parcel with no irrigation history. Using 0.6 acre-feet per acre, the ordinance’s default cap where no use data exist, as a rough planning figure, that is 12 acre-feet a year, far above the 2-acre-foot line. Inside the Public Trust Review Area, a new well for that use would not fit the low water use class and would likely need discretionary review. At the 2026-2027 rate of $46.04, 12 acre-feet would cost about $552 a year in basin fees, a small number next to the risk that the well is delayed or denied.

Alternatives such as winter storage ponds and recycled water can reduce dependence on summer pumping; see our guides to vineyard ponds and reservoirs and recycled water for vineyards. The broader development steps are in vineyard development and replanting, and the full buyer checklist is in our vineyard due diligence guide.

What this means for vineyard sellers

A seller who can document water usually gets a cleaner sale. Gather well permits, completion reports, meter readings, recent yield tests, any conservation or frost protection plans, GSA bills and GUIDE data before listing. A buyer’s appraiser and lender will ask about water too, and well-documented supply supports the price you ask; our guide to vineyard valuation explains why.

Rural parcels across the county, from the Russian River Valley to the edges of Fulton, Penngrove and Glen Ellen, commonly rely on wells, so these rules reach homes as well as vineyards. Our Sonoma County guide explains how county rules apply outside city limits. Napa has a different system, covered in our guide to Napa groundwater rules.

This is general information, not legal advice; talk to a California water law attorney and a licensed hydrogeologist or well professional about a specific property.

Questions people ask

Can I still get a well permit in Sonoma County?

On October 24, 2026, Permit Sonoma’s website still said it could issue non-emergency permits under the Court of Appeal’s March 2025 stay and had not posted an update on the August 2026 ruling. The case is back in the trial court for a new judgment, so confirm current status with Permit Sonoma before you rely on a new well.

Is there a well moratorium in Sonoma County?

Permit Sonoma was not reporting one when we checked on October 24, 2026. A trial court order served December 17, 2024 required the county to suspend non-emergency well permitting, but the Court of Appeal stayed it on March 27, 2025, and its August 2026 opinion directs the trial court to vacate that judgment. The appellate court expressed no view on whether a moratorium or interim measures are appropriate going forward.

Does the well ordinance limit how much I can irrigate my vineyard?

It can. For agricultural sites using more than 2 acre-feet a year under the existing use or net zero classes, growing-season groundwater use for vineyards and orchards is capped at pre-existing levels, or 0.6 acre-feet per acre per year if there is no data.

Do I need a meter on my well?

Existing wells do not. Most new non-residential and mixed-use wells do, with monthly readings reported once a year. A new well for a single residential user at or below 2 acre-feet a year is exempt.

How much is the groundwater fee for a vineyard?

It depends on the agency’s estimate of your use. For 2026-2027, non-municipal users in all three basins pay $46.04 per acre-foot after the county contribution, billed on the property tax bill; a typical rural home is estimated at 0.5 acre-feet, or $23.02.

Which groundwater agency covers my parcel?

Only parcels in the Santa Rosa Plain, Sonoma Valley or Petaluma Valley basins are in a medium-priority basin with an agency fee. Check the agency maps, or the parcel’s tax bill for the fee line.

Does the ordinance apply to my pond or creek diversion?

No. Surface water diversions are regulated by the State Water Resources Control Board; a well that supplies a diversion regulated by the state board is one of the ordinance’s ministerial classes.

If a Sonoma vineyard you are considering depends on new or expanded well water, we can help you line up the records and questions before you write an offer. Contact Diamond Real Estate Group to talk through a specific property.

Sources & notes

Permitting status can change quickly while the case is on remand; we will update this page as the county reports changes.

Last reviewed October 2026 by Matthew Martinez.