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Larkfield-Wikiup, CA: Homes, Rebuilds, Sewer and County Rules

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

Larkfield-Wikiup is an unincorporated community in Sonoma County just north of Santa Rosa, east of Highway 101 along Old Redwood Highway and Mark West Springs Road. It is not part of the City of Santa Rosa, so the County of Sonoma, through Permit Sonoma, handles planning and building permits. The Census Bureau’s 2024 five-year estimates put the community at about 8,765 residents and 3,616 housing units across 5.3 square miles.

The 2017 Tubbs Fire burned through much of the area, and the rebuild reshaped its housing, utilities and permit records. This page covers what to verify on a Larkfield-Wikiup property: county jurisdiction, rebuild permits, the sewer extension and its financing liens, the water system, fire and flood zones, schools by district name, getting around, and selling.

Larkfield-Wikiup homes for sale

Larkfield-Wikiup market report

Where Larkfield-Wikiup is and who governs it

Larkfield and Wikiup are neighboring subdivisions in the Mark West area north of Santa Rosa city limits. Many addresses carry a Santa Rosa mailing address, but a mailing address doesn’t put a parcel inside the city. Check the county assessor’s parcel record or Permit Sonoma’s maps to confirm jurisdiction.

Because the area is unincorporated, county zoning, building, septic and fire prevention rules apply, not Santa Rosa’s. The Sonoma County Fire District lists Larkfield, Wikiup and Mark West among the communities it serves, alongside Windsor and Fulton. For a side-by-side look at how city and county ownership differ, see our guide to city versus county ownership in Sonoma County.

Transfer tax is simpler here than in town. Sonoma County’s documentary transfer tax is $0.55 per $500 of value. Santa Rosa and Petaluma add their own $2.00 per $1,000 city tax, but that city tax doesn’t apply to a parcel outside Santa Rosa’s limits. In Diamond’s North Bay markets the seller customarily pays transfer tax, but it is negotiable and local custom varies.

Housing stock and the Tubbs Fire rebuild

The Tubbs Fire started on October 8, 2017. CAL FIRE’s list of the most destructive California wildfires records it at 36,807 acres, 5,636 structures and 22 deaths across Napa and Sonoma counties.

In early 2018, county planning staff told the Argus-Courier that the fire destroyed nearly 740 residences across the greater Larkfield-Wikiup and Mark West Springs area. Sonoma Water describes the Larkfield Estates neighborhood as heavily impacted by the October 2017 fires.

The result is a mixed housing stock on many streets: homes that survived, post-fire rebuilds and, in some places, lots that were never rebuilt. These are different products. Compare a rebuild with other rebuilds, a survivor with other survivors, and treat a vacant lot as land, with its own questions about permits, utilities and access. Our Fountaingrove guide covers a similar rebuild pattern inside Santa Rosa city limits.

What the county’s parcel records show

To describe the housing stock without guessing, we queried Sonoma County’s public parcel layer (the One Stop parcel map) in October 2026 for unincorporated parcels in the core of the community, east of Highway 101. Of 1,321 parcels with a recorded year built, 95 date from before 1960, 346 from 1960 to 1979, 612 from 1980 to 1999, 90 from 2000 to 2017 and 178 from 2018 on. The 2018-and-later group mixes fire rebuilds with new homes, and some rebuilt houses may still carry their original year, so use the records as a starting point and confirm each house’s permit history.

Lots are mostly suburban in size. By the map’s calculated parcel areas, about 44 percent of those parcels are under 8,000 square feet, 34 percent run from 8,000 square feet to half an acre, about 9 percent are half an acre to an acre, and about 12 percent are larger than an acre. Roughly 72 percent (946 parcels) are zoned R1, and 38 parcels are classified as condominiums.

Rebuild streets. The most homes built in 2018 or later are on Pacific Heights Drive, Wikiup Drive, Jean Marie Drive, Carriage Lane and Carriage Court, Wikiup Bridge Way, Misty Court and Vista Grande Drive.
Wikiup hills. On Vista Grande Drive, Los Altos Court and Los Arboles Way, sampled parcels run from about 0.7 to 2.9 acres, with most homes recorded as built between the mid-1960s and late 1980s. They are zoned R1 with combining designations such as OAK, RC50/50, VOH and G, each of which adds its own rules; ask Permit Sonoma what they mean for a given project.
Farther into the hills. Parcels on Hop Ranch Road, Noonan Ranch Circle and Deerwood Drive carry planned community (PC) or rural residential (RR) zoning rather than R1.

Records to pull on a rebuilt home

The Permit Sonoma permit history for the address: demolition, rebuild, solar, septic or sewer connection and any later additions.
Proof that each permit reached final inspection. An open or expired permit is a negotiation item and can delay a lender or insurer.
The building code edition the rebuild was permitted under. Many were reviewed under Chapter 7A of the Building Code; work permitted from January 1, 2026 falls under the new California Wildland-Urban Interface Code, Title 24 Part 7.
Transferable warranties for the roof, windows, solar and major systems.
A comparison of permitted square footage and bedroom count with the listing and the assessor’s record.

Sewer, septic and the Larkfield Estates financing liens

Part of the community is served by the Airport/Larkfield/Wikiup Sanitation Zone, which Sonoma Water operates. The zone covers 2,100 acres, began operating in 1983, provides tertiary treatment with a design capacity of 900,000 gallons per day, and uses all of its recycled water for irrigation. Sonoma Water’s page says some or all of the zone may consolidate with the Windsor Water District in the future.

Before the fire, many Larkfield Estates homes used septic systems even though the neighborhood sat inside the sanitation zone boundary. After the fire, the Board of Supervisors approved a sewer extension on February 5, 2019 that offered 143 parcels a connection. Construction began in January 2020 and was completed that year. Participation was voluntary, and owners with functioning, county-approved septic systems could keep them.

Owners who joined could finance their share. Sonoma Water describes a construction loan of 30 years, with a 10-year grace period followed by 20 years of payments at a fixed 2.5 percent, and a separate connection fee loan of 20 years at 2 percent. Both are secured by a lien on the property and do not subordinate to a mortgage, and construction loan payments are added to the property tax bill.

For a buyer, that means three checks on any Larkfield Estates house:

Is it connected to sewer, or still on septic? If septic, get the system’s permit record and an inspection. Diamond may refer you to partners we work with; you’re free to choose any provider.
Does the property tax bill show a sewer financing charge? Ask Sonoma Water for the remaining balance and whether it will be paid off at closing or assumed.
Will your lender accept the lien? Because it doesn’t subordinate to a mortgage, raise it with the lender early.

Owners who didn’t connect can still connect later, but Sonoma Water says they will pay construction costs and connection fees at future rates, without the financing, and must build their own lateral to the street main. Sonoma Water also says owners are not required to connect when the property sells. For septic and well basics elsewhere in the county, see our guide to wells, septic and rural utilities in Sonoma County.

Water service

Much of the area gets water from California American Water’s Larkfield district, an investor-owned system regulated by the California Public Utilities Commission. A CPUC decision describes the district as serving the Larkfield and Wikiup subdivisions east of Highway 101 and the community of Fulton west of it, with about 2,400 customers.

The utility’s 2023 water quality report lists two sources: groundwater wells pumping from the Glen Ellen formation, which supplied 67.2 percent of the water, and water purchased from the Sonoma County Water Agency, which supplied 32.8 percent. Ask for the most recent report and a recent bill so you know the rate structure before you buy.

A parcel outside the system’s service area will need its own well. If you’re looking at land toward the hills, confirm the water source before you make an offer, not during escrow.

Fire, flood and other hazards

Check the fire hazard severity zone parcel by parcel. Permit Sonoma posts the State Fire Marshal’s maps, including the 2025 Local Responsibility Area map for unincorporated Sonoma County and an interactive map. Our guide to fire hazard severity zones in the North Bay explains SRA and LRA designations and what each zone triggers.

If the home is in a High or Very High zone, the seller must give the buyer defensible space documentation under Civil Code 1102.19. For State Responsibility Area parcels in those zones, Permit Sonoma’s Fire Prevention staff perform the inspection for a fee, and the assessment is valid if completed within six months before the sale. Our AB 38 inspection guide walks through the process.

Mark West Creek and its tributaries run through the area, so check FEMA’s Flood Map Service Center for the parcel’s flood zone, and read the natural hazard disclosure report in escrow. Our guide to flood zones in the North Bay covers what a mapped zone means for insurance and lending.

Schools and services

The local elementary district is the Mark West Union School District, whose schools are John B. Riebli Elementary, San Miguel Elementary, Mark West Elementary and Mark West Charter School. The district office is at 305 Mark West Springs Road and enrolls students in grades TK through 6.

Attendance boundaries are set by address, so confirm the assigned schools, including the high school district, with the districts directly. Fire service comes from the Sonoma County Fire District, whose district office is on Old Redwood Highway in Windsor.

Getting around

Highway 101 runs along the community’s west side, and Old Redwood Highway parallels it north toward Windsor and south into Santa Rosa. Mark West Springs Road runs east from Old Redwood Highway into the hills.

The SMART train’s Charles M. Schulz-Sonoma County Airport station is at 1130 Airport Boulevard, west of the freeway, with free day-use parking and paid overnight parking, near the county airport it is named for.

Nearby areas worth comparing include Santa Rosa for city services and a wider range of housing, Windsor to the north, and Fulton across the freeway.

Rules that affect owners and investors

County rules govern accessory dwelling units, vacation rentals and land use here. Our article on building lots and ADUs in Sonoma County explains the county’s ADU path, and the Sonoma County vacation rental rules article covers permits and zoning limits for short-term rentals.

Short-term rentals are limited. Permit Sonoma’s vacation rental page says they are not allowed in R1, R2 or R3 districts, in Vacation Rental Exclusion (X) combining districts, on Williamson Act land or in accessory dwelling units, and that where they are allowed they need a zoning permit, a certified property manager and a vacation rental license. When we checked the county’s parcel zoning records in October 2026, no parcel in the Larkfield-Wikiup area carried the X designation, but most are zoned R1, which rules out a vacation rental for most homes here. For RR or PC parcels in the hills, check the county’s Vacation Rental Map Viewer and confirm with Permit Sonoma.

Long-term rentals fall under county rules as well as state law. The Board of Supervisors passed Ordinance No. 6496, the Residential Tenancy Protections Ordinance, on September 17, 2024, for the unincorporated county. For the units it covers, just cause protection begins when the tenancy starts instead of after the state law’s waiting period, and no-fault relocation assistance is the greater of HUD Fair Market Rent or the actual monthly rent. For notices served on or after January 1, 2025, landlords must file a copy of any termination notice with the county’s Tenant Protections Portal within three days of serving it, whether or not the state Tenant Protection Act covers the tenancy.

The ordinance does not set a rent cap; the state cap may still apply. Our guide to AB 1482 for landlords explains the state rules. This is general information, not legal advice; talk to a California landlord-tenant attorney about a specific tenancy.

Selling a home in Larkfield-Wikiup

Buyers here ask detailed questions about fire history, permits and utilities, and a seller who answers them up front usually spends less time renegotiating. Before listing:

Assemble the full Permit Sonoma file for a rebuilt home, with final inspections and the code edition.
Document sewer or septic status, and get the payoff figure for any sewer financing lien on the tax bill.
Order the defensible space inspection early if the parcel is in a High or Very High zone.
Gather the water provider’s account details and any well test or septic inspection reports.
Price against the right comparables: rebuilds against rebuilds, survivors against survivors.

Our guide to comparative market analysis explains how pricing comparisons are built.

Questions people ask

Is Larkfield-Wikiup part of Santa Rosa?

No. It is an unincorporated community in Sonoma County north of Santa Rosa city limits, even though many addresses use a Santa Rosa mailing address. Permit Sonoma issues building permits, and Santa Rosa’s city transfer tax doesn’t apply.

How many homes burned in Larkfield in the Tubbs Fire?

County planning staff told the Argus-Courier in 2018 that the fire destroyed nearly 740 residences across the greater Larkfield-Wikiup and Mark West Springs area. Check the history of the specific address, since survivors and rebuilds sit side by side.

Is Larkfield on sewer or septic?

Both exist. Parts of the area are served by the Airport/Larkfield/Wikiup Sanitation Zone, and 143 Larkfield Estates parcels were offered a sewer connection after the fire, but connecting was voluntary. Owners who financed a connection repay it through a lien, with construction-loan payments on the property tax bill, so confirm each house’s status and any balance.

Can I run a vacation rental in Larkfield-Wikiup?

Usually not. County rules bar vacation rentals in R1 districts, and most parcels here are zoned R1. We found no vacation rental exclusion (X) zoning in the area, so some rural RR parcels may qualify with a permit; check the county’s Vacation Rental Map Viewer.

Who provides water in Larkfield-Wikiup?

Much of the area is served by California American Water’s Larkfield district, regulated by the CPUC. Its 2023 report shows about two-thirds of supply from local wells and one-third purchased from the Sonoma County Water Agency.

What school district serves Larkfield?

The local elementary district is the Mark West Union School District, which runs Riebli, San Miguel and Mark West elementary schools and Mark West Charter School. Confirm assigned schools by address with the district.

Do Sonoma County tenant protections apply in Larkfield-Wikiup?

Yes, for covered units. Ordinance 6496 applies in the unincorporated county: just cause protection starts at move-in, no-fault relocation is the greater of HUD Fair Market Rent or actual rent, and termination notices must be filed with the county within three days.

Is Larkfield-Wikiup in a fire hazard severity zone?

Parts of it may be, and the answer depends on the parcel. Check Permit Sonoma’s interactive map and the State Fire Marshal’s viewers, and read the natural hazard disclosure report in escrow.

If you’re buying or selling in Larkfield-Wikiup and want a property’s permits, sewer status and fire zone sorted out before you commit, start with a home valuation or browse our Sonoma County real estate guide.

Sources & notes

Last reviewed October 2026 by Matthew Martinez.