Commercial Real Estate in Boonville: Downtown Anderson Valley Zoning, Septic and the Planned Water and Sewer Systems

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

Boonville is the commercial center of Anderson Valley, a string of storefronts, restaurants, inns, tasting rooms and service businesses along State Route 128, with the county fairgrounds at its heart. Vineyards, orchards and ranch land surround the town. Today almost every Boonville property runs on its own well and septic system, and that drives what a building can be used for. Confirm zoning, water and wastewater for each parcel before relying on this page.

Who controls the parcel

Boonville is unincorporated, so Mendocino County Planning and Building Services applies the county’s Inland Zoning Code. It is not in the Coastal Zone. Policy direction comes from the General Plan’s Anderson Valley chapter (Chapter 6, August 2009).

The Anderson Valley Community Services District provides volunteer fire and ambulance service, parks and recreation, street lighting and the Boonville Airport. It is also leading the town’s drinking water and wastewater projects. The General Plan notes that CAL FIRE staffs a Boonville station for about six months of the year, and that the fairgrounds serve as a base for major emergencies. See our Mendocino County commercial guide for countywide rules.

Boonville zoning for commercial and mixed use

Downtown Boonville parcels generally carry the county’s rural community or commercial districts, with agricultural zoning around the town. Confirm each parcel with a Letter of Zoning or the county’s zoning map.

District	Intended uses	Notes
R-C Rural Community (Ch. 20.084)	A mix of homes, shops and light industry in rural towns	35 ft. 20 ft front and rear, 6 ft side setbacks. Commercial needs no minimum lot only with both water and sewer service
C-1 Limited Commercial (Ch. 20.088)	Neighborhood-serving shops and services	Smaller-scale commerce
C-2 General Commercial (Ch. 20.092)	Full-service commerce at community cores	50 ft height. No side setback unless next to non-commercial land
I-1 / I-2 Industrial (Ch. 20.096, 20.100)	Light and heavier industry	Where mapped
Agricultural and resource districts	Vineyards, orchards, grazing, timber	General Plan Policy CP-AV-19 says to retain them throughout the valley

Under the R-C rules, a parcel outside any water or sewer district needs at least 40,000 square feet. That is why the planned public systems matter so much for downtown lots.

What the Anderson Valley plan says about downtown

The General Plan’s community policies point growth and commerce at downtown Boonville:

CP-AV-1: Concentrate new development in Yorkville, Boonville, Philo and Navarro, and discourage new retail outside them.
CP-AV-4: New buildings should reflect the historic character of downtown Boonville.
CP-AV-5: Keep and expand downtown Boonville as the community’s commercial and social center.
CP-AV-6: The county will help prepare town plans if the community wants them.
CP-AV-11 and 12: Size any water and sewer system only for planned growth, and encourage the CSD to provide those services.
CP-AV-17: Support the Boonville Airport Master Plan and upgrades for economic development and emergency use.

For a buyer, this means a commercial use in town is aligned with county policy, while a retail use out on the highway between towns is not.

Septic, wells and the Boonville water and sewer project

The CSD’s 2018 Notice of Preparation explains the problem. Downtown businesses and homes rely on individual wells and septic systems, many of which do not meet current state and county standards. Many lots are too small for a compliant leach field. A 1974 county survey found surfacing sewage at 11% of properties. In 2016 the CSD found E. coli in 70% of 23 sampled wells. About 80% of parcels use private wells.

The proposed wastewater service area covers the dense parts of town along Highway 128, including the business district and the fairgrounds. It counts about 139 connections, 37 of them non-residential. A small tertiary plant is planned just south of the airport. The project has two CEQA records, a 2016 drinking water planning exemption and the 2017–2018 water and wastewater notices.

Status. The CSD’s project page says planning was funded by two state grants. Engineering reports went to the State Water Board for review, and a draft EIR was expected in spring 2026. The district still needs LAFCo approval to activate water and sewer powers and a Proposition 218 rate process, and construction has not started. Price any Boonville property on its current well and septic, not on the future system.

Lodging, tasting rooms and fairground events

Transient occupancy tax. Inns, motels and vacation rentals register with the county and collect TOT under Chapter 5.20. The chapter sets an 8% base and authorizes an additional 2% approved by voters in March 1997. A separate registration certificate is needed for each parcel. Lodging also pays a Business Improvement District assessment through the Treasurer-Tax Collector.
Event peaks. The NOP estimates wastewater flow rising from about 60,000 to 90,000 gallons per day during major fairground events, about three times a year. Restaurants and lodging feel those peaks, and septic systems must be sized for them.
Wineries and tasting. Most vineyard land is agriculturally zoned. Tasting rooms, processing and events need the use permits the inland code requires for the specific district. Check the permit history before buying a property marketed for hospitality.
Cannabis. The county’s Cannabis Division licenses cultivation. Confirm the zoning and license status of any cannabis-related site.

Transfer tax, business tax and property tax

The County Recorder collects documentary transfer tax and requires a Preliminary Change of Ownership Report with each deed, but its fee schedule does not post the rate, so confirm the amount on the escrow estimate. Boonville has no city, so no city transfer tax applies. A sale generally triggers Proposition 13 reassessment. Vineyard parcels may be under a Williamson Act contract, which affects taxes and uses.

Due diligence that matters in Boonville

Start with our commercial due diligence checklist, then add:

Order a county Letter of Zoning to confirm the district and overlays.
Get the county Environmental Health septic file, a septic inspection and well water quality tests for bacteria and nitrate.
Check whether the parcel is inside the planned CSD water and wastewater service areas.
For a restaurant or inn, confirm the use permit, TOT registration and the septic capacity for peak event weekends.
For agricultural land, check the Williamson Act status and any winery or tasting permits.
Review wildfire exposure and fire water supply, since the town has limited hydrants today.

Questions people ask

Is Boonville on public sewer or water?

Not yet. Properties use private wells and septic. The Anderson Valley CSD is planning both systems, but construction depends on state funding, LAFCo approval and a rate process.

Who sets zoning in Boonville?

Mendocino County, under its Inland Zoning Code and the General Plan’s Anderson Valley policies.

Does the county want commercial growth in Boonville?

Yes. The General Plan calls for keeping and expanding downtown Boonville as the valley’s commercial and social center, and it discourages new retail outside the four towns.

Why does water and sewer matter for lot size?

In the R-C district, a parcel with neither service needs 40,000 square feet, while commercial use with both services has no minimum.

What lodging taxes apply?

County transient occupancy tax under Chapter 5.20 plus a Business Improvement District assessment.

Is there a Boonville transfer tax?

No city tax. The county documentary transfer tax applies; confirm the amount with escrow.

Does Diamond handle commercial property in Boonville?

Contact Matthew Martinez to discuss buying, selling or leasing commercial property in Boonville.

Sources & notes

Note: We did not verify the zoning of specific downtown parcels or whether the additional 2% TOT is currently collected. Project status reflects the CSD’s page as of October 2026.

This page is general information, not legal or tax advice. Last reviewed October 2026 by Matthew Martinez.

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