Knights Valley Vineyards: County-Line Boundary, Frost Water, Fire Zones and Permits

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

Knights Valley is the easternmost corner of Sonoma County’s wine country, a broad upland valley tucked against the Napa and Lake county lines below Mount St. Helena, a short drive over the hill from Calistoga. It is a Sonoma appellation governed by Sonoma County rules even though its closest town is in Napa County, and its boundary has not changed since 1983. Both facts matter when you are buying vineyard land here.

Knights Valley at a glance

Where the appellation runs

The boundary in 27 CFR 9.76 begins where the Sonoma/Lake County line meets the north line of Section 11, T. 10 N., R. 8 W. Most of the western and southern line follows township and section lines; it also runs south along Franz Valley Road from Franz Creek and follows Franz Creek east for roughly 14,000 feet. The Sonoma/Napa County line forms the eastern and southeastern edges, and the Sonoma/Lake line closes it on the north. The text names no peaks as boundary features; Mount St. Helena and Detert Reservoir appear only as map names. It has been in the CFR since 1983 without amendment.

That county-line boundary has a practical effect. A ranch that straddles the Napa line can have its Sonoma side inside Knights Valley and its Napa side outside it, under different county rules and possibly different appellation names. Map the parcel line against the AVA line before planning labels or plantings.

Knights Valley is listed among the six areas lying entirely within Northern Sonoma. The Fountaingrove District, established in 2015, lies to its south and does not overlap it. In that ruling TTB described Knights Valley as warmer than Fountaingrove, with broad stream valleys and soils formed from river deposits. Alexander Valley’s boundary also uses the Mount St. Helena and Jimtown quadrangles, so check the western edge of any ranch near Franz Valley Road against both rules.

More context: Sonoma wine appellations and our post on Fountaingrove District geology.

Sonoma rules, Napa neighbors

Buyers who know Napa County are often surprised that none of Napa’s Agricultural Preserve, winery definition or groundwater rules apply on the Sonoma side of the line. In Knights Valley, the County of Sonoma handles zoning, winery use permits and well permits, and the Sonoma County Agricultural Commissioner handles vineyard planting permits. If you are comparing a Knights Valley ranch with one near Calistoga, set the two rulebooks side by side. Our Calistoga town versus vineyard property page covers the Napa side.

Frost water and the Russian River system

Most of Knights Valley drains west toward the Russian River through the Franz Creek system named in the CFR boundary. If a parcel drains to the Russian River, California’s frost rule, 23 CCR 862, governs water diverted for frost protection from March 15 to May 15. Diverters must work under a water demand management program approved by the State Water Board, with stream stage monitoring, a stranding-risk assessment and an annual report due September 1. Groundwater pumping is covered when it contributes to a drop in stream stage during a frost event. Confirm the drainage with a hydrologist for parcels close to the county line.

Sonoma County’s VESCO application asks for a frost protection registration or negative declaration for Russian River watershed parcels, and the registration fee comes due again on a change of owner or operator.

Knights Valley is not one of the three areas with a Sonoma County groundwater sustainability agency, which are the Santa Rosa Plain, Sonoma Valley and Petaluma Valley. That leaves county well permits and the frost rule as the main water controls, but confirm the basin’s current prioritization with DWR. See vineyard water rights, Sonoma County groundwater rules and vineyard ponds and reservoirs, since storage ponds are common on upland ranches.

Planting and clearing: VESCO

Knights Valley ranches often combine a valley-floor block with wooded hillsides. Expanding into the woods brings in the county’s tree-removal standards under VESCO, per the site development FAQ:

• Removing more than half an acre of tree canopy (orchard trees excepted) triggers extra standards, including erosion modeling to show no net increase.
• Level II tree-removal projects need an engineering geologist’s report.
• Ridgetop tree removal requires a 50-foot setback, either as a 25-foot grassy turnaround plus 25-foot no-touch zone or a full 50-foot no-touch zone.
• Planting is prohibited on natural slopes over 50%, and tree removal is barred above 40% on cohesionless soils.
• Valley oaks, pines, firs and redwoods may need separate county or CAL FIRE permits.

Floor-only replanting is simpler: replanting on non-erodible soils stays Level I up to 30% slope. For a larger program see vineyard development and environmental constraints.

The North Coast Regional Water Board’s vineyard order R1-2024-0056, approved June 2025, is expected to open enrollment July 1, 2028. Its geographic reach should be confirmed for parcels near the Napa line.

Fire hazard and access

Knights Valley is rural and much of its hillside land is wooded, so fire exposure is central to insurance and lending. Check the parcel on CAL FIRE’s Fire Hazard Severity Zone maps. The State Responsibility Area map took effect April 1, 2024. Expect to document defensible space, water storage for firefighting and road access for any residence or winery building. Read vineyard and winery insurance, wildfire smoke taint and home hardening for wildfire.

Zoning, wineries and the Williamson Act

Sonoma County’s 2023 winery standards in Sec. 26-18-260 apply to new or modified winery use permits in LIA, LEA and DA zones. On a remote ranch the parking and traffic rules stand out. Overflow parking and shuttles are allowed only for events and only if the permit says so. Parking on public or private roads, including shared vineyard roads, is prohibited. Events using overflow parking need a traffic management plan.

Large ranches here are good candidates for Williamson Act contracts. Under the county’s procedure for contracted parcels, Type II contracts need at least 40 acres. A material breach can carry a penalty of 25% of the unrestricted value of affected land and buildings, including large non-agricultural buildings built after 2004. Confirm current county rules, since that policy is from 2007. See Sonoma County agricultural zoning, winery use permits and Williamson Act.

A due diligence list for a Knights Valley vineyard

Use with the full vineyard due diligence guide.

• Map the parcel against 27 CFR 9.76 and the Sonoma/Napa and Sonoma/Lake county lines.
• If the ranch crosses the Napa line, list which acres fall under each county and which appellation names they can use.
• Confirm which watershed each block drains to, and get any 23 CCR 862 program enrollment.
• Re-register frost protection with the county at transfer.
• Pull water rights filings, reservoir and pond permits, well logs and pump tests.
• Collect VESCO permits, including any tree-removal approvals and geologist reports.
• Check CAL FIRE hazard zone and SRA status, plus defensible space and water storage.
• Review road easements and maintenance agreements for private access.
• Read any winery use permit’s parking, event and traffic conditions.
• Confirm Williamson Act contract type, preserve number and any nonrenewal notice.

Questions people ask

Sources & notes

1. Cornell LII: 27 CFR 9.76, Knights Valley
2. Federal Register: Expansions of the Russian River Valley and Northern Sonoma Viticultural Areas (2011)
3. Federal Register: Establishment of the Fountaingrove District Viticultural Area (2015)
4. Cornell LII: 27 CFR 9.53, Alexander Valley
5. Cornell LII: Cal. Code Regs. tit. 23, § 862
6. County of Sonoma: GSAs seek input from agricultural groundwater users
7. Sonoma County Agriculture/Weights & Measures: Site development FAQ and VESCO application
8. North Coast Regional Water Board: Vineyard Order R1-2024-0056
9. CAL FIRE OSFM: Fire Hazard Severity Zones
10. Sonoma County: Zoning Code Sec. 26-18-260
11. Permit Sonoma: Policy 8-1-8, Williamson Act parcels

General information, not legal or tax advice. Last reviewed November 2026 by Matthew Martinez.

Related: Sonoma County vineyards · Calistoga real estate guide · Alexander Valley vineyards · Chalk Hill vineyards · Vineyard due diligence · Vineyard water rights · All vineyard and winery guides