Two land search sites will tell you two different stories about the same county. One puts the average price per acre in Santa Clara County near $31,635 for rural listings. Another, using a different filter, puts the median at $80,499 an acre. Neither number is wrong. Both are close to useless for a buyer under contract on a specific parcel, because in unincorporated Santa Clara County the price the listing quotes is almost never the number that governs what the buyer can do with the land.
Roughly 43% of the county sits inside that gap. That is the share of Santa Clara County land, more than 362,704 acres, currently under a Williamson Act contract with the County. If your parcel is in the unincorporated area, the odds it carries a land-conservation contract, a well-permit obligation, a septic clearance requirement, or all three, are high enough that the diligence sequence should start before the offer, not after.
The number on the listing versus the number that governs
A per-acre price answers a question the county does not care about. The questions that decide whether you can build a residence, dig a well, add a barn, or even hold the parcel long enough to develop a plan are answered by four different agencies, on four different calendars.
| What the buyer usually asks | What actually governs the answer |
|---|---|
| "What's this land worth per acre?" | Whether it's under a Williamson Act or Farmland Security Zone contract, and how much time remains on the non-renewal clock |
| "Can I build a house here?" | A Compatible Use Determination from Planning, then a building permit under the 2025 California Building Standards Code |
| "Is there water?" | A Valley Water well permit issued through the CityWorks portal, after Department of Environmental Health clearance and setback review |
| "Can I add on later?" | A current septic pumper's report, an OWTS clearance from DEH, and any Fire Marshal, Roads and Airports, or Land Development Engineering approvals the parcel triggers |
Three of the four rows changed in the last two years. That is the story of this post.
The contract you may be inheriting
The Williamson Act is a voluntary tax-reduction contract, not a zoning designation. A landowner agrees to keep the parcel in commercial agricultural use for a ten-year rolling term, and in exchange the Assessor values the land on an income basis rather than market value. A Farmland Security Zone contract works the same way with a twenty-year term. Contracts renew automatically each January 1 unless either party files a notice of non-renewal.
Two features of the contract matter to a buyer more than the tax savings:
- The contract runs with the land. A buyer inherits it. The Clerk of the Board processes non-renewal notices, and any notice received after October 1 does not begin its wind-down until the following calendar year. A notice filed October 1, 2026 begins its clock in 2027, which means nine years of restricted use remain before the contract fully lapses.
- While the contract is active, the land is restricted to commercial production of agricultural commodities and uses on the compatible-use list. A residence can qualify as compatible, but only through a Compatible Use Determination reviewed by Planning under County Ordinance Code Section C13-15.
Buyers who assume they can non-renew at closing and build within a year are reading the contract wrong. Buyers who plan to actively farm, run cattle, or plant vineyard blocks are reading it right, and the tax basis, valued on income under Section 423 of the California Revenue and Taxation Code, becomes a durable asset rather than a trap.
What changed in 2024, and why the old blog posts are stale
On March 26, 2024, the Board of Supervisors repealed and reenacted Division C13 of the Code of Ordinances in its entirety through Ordinance No. NS-1203.130. The prior version had been on the books since 2006. If you are reading a summary of Santa Clara County's Williamson Act rules that predates spring 2024, the procedural sections, the appeals process, the compatible-use development guideline, and the substandard-parcel non-renewal procedure have all been rewritten.
The Planning Division now administers a tiered appeals process with the Board of Supervisors as the final level. A separate Guideline for Policies Governing the Exchange of an Existing Williamson Act Contract for an Open Space Easement lets certain owners move a contract into an Open Space Easement, a 15-year or perpetual instrument with its own compatible-use rules.
For a buyer, the practical translation is that any advice on land-conservation restrictions in this county older than eighteen months should be verified against the current code before it becomes the basis of an offer.
The 2026 well-permit calendar
The Santa Clara Valley Water District's Well Ordinance Program made two changes in the first weeks of 2026 that shifted the timeline on any parcel that needs a new well, a replacement well, or a well destruction as a condition of sale.
- January 1, 2026: new fee schedule. Valley Water raised well construction, destruction, reconstruction, exploratory boring, and standby permit fees for the first time since 2017. Inspection surcharges apply when the site is not ready or when the permittee requests additional inspections.
- February 1, 2026: paperless only. The Well Permitting Unit no longer accepts paper applications. Every permit is filed through the CityWorks public portal, with the account in the name of the individual applicant rather than the business. The Wells Unit hotline at 408-630-2660 handles the transition questions the portal cannot.
Even before Valley Water sees the file, the County's Department of Environmental Health has to clear the well location. DEH reviews the site and completes a field visit in roughly five working days after fees and application are submitted, then forwards the paperwork to Valley Water, which typically takes one to two more weeks to issue the construction permit to the C-57 licensed driller. The realistic floor is three to four weeks of clean processing on a straightforward site, and a permit is valid for one year from issuance.
The setbacks decide whether the site is straightforward. From the proposed well location:
- 100 feet to a septic tank or pit privy
- 100 feet to an animal or fowl enclosure
- 100 feet to a detention or retention pond
- 100 feet to chemical or fuel storage
- 150 feet to a cesspool or seepage pit
On a small rural parcel with an existing septic system, a barn, and a fuel tank, those five circles do not always leave a legal spot for a new well. That is a discovery every buyer wants to make during inspection contingency, not after close.
Septic clearance sits under every future improvement
If the parcel has an onsite wastewater treatment system, the OWTS is a governing document for any addition, accessory structure, or new dwelling. DEH will not issue a Septic/OWTS clearance for a proposed addition without a current septic pumper's report, within the last three years, that notes the condition of the tank and includes a thirty-minute water test where applicable. Additional soil testing may be required to confirm sizing and setbacks.
An as-built diagram of the existing OWTS is available through a public-records request to the Consumer Protection Division. Allow up to ten days. On a parcel where the seller cannot produce recent pumping records, budgeting for a pump, an inspection, and a possible upgrade quote before removing contingencies is cheaper than discovering an undersized leach field after close.
The Compatible Use Determination is the real permit
Here is the sequence that catches buyers off guard on Williamson Act land: the building permit is not the first approval. On contracted land, a Compatible Use Determination has to come first, and Planning evaluates it in two parts. The land has to be documented as devoted to commercial production of agricultural commodities per the County's Guideline for Commercial Agricultural Use. The proposed use, including a residence, has to be found compatible with and incidental to that documented production.
A completed Declaration Regarding Agricultural Income on Williamson Act Property has to accompany the submission. If a favorable determination cannot be issued, the parcel is generally not eligible for land-use approvals or building permits until the contract is non-renewed, cancelled, or exchanged for an Open Space Easement. That is why the October 1 non-renewal deadline is a transaction date, not an administrative one.
Buyers planning a primary residence on contracted land should be running the Compatible Use Determination question in parallel with financing, not after inspections.
The rural-parcel add-ons the offer needs to anticipate
The 2025 California Building Standards Code (Title 24) took effect January 1, 2026 and applies to permits filed and issued in the current 2026 cycle, subject to County amendments. On a rural or hillside parcel, the building permit is rarely the only approval. Fire Marshal review can pull in ignition-resistant construction requirements for roofing, siding, vents, decks, and vegetation clearance if the parcel is mapped in a fire-hazard zone. Land Development Engineering reviews floodplain construction, elevation, and flood-resistant materials. Fault, landslide, expansive-soil, and steep-slope conditions can require geotechnical reports and engineered foundations. New driveways or access improvements pull in the Roads and Airports Department.
Each of these is a small, ordinary requirement in isolation. Stacked on a single rural offer, they compress the contingency window in ways urban buyers rarely have to price.
FAQ
Does the Williamson Act contract transfer to me at closing? Yes. The contract runs with the land, and the January 1 renewal date is the same regardless of who owns the parcel on that date.
If I file non-renewal at closing, when can I build a non-agricultural use? The non-renewal begins the following January 1 and runs nine additional years before the contract fully lapses. During that window, any building permit still requires a Compatible Use Determination, or a contract cancellation, or an exchange to an Open Space Easement.
Can I dig my own well? Water well construction has to be performed by a licensed C-57 Well Drilling Contractor operating under a Valley Water permit issued through CityWorks, with DEH clearance on the location first.
Is the low agricultural assessment worth keeping? Often, yes, if the parcel is actively farmed or grazed. The assessment is based on income under Section 423 of the Revenue and Taxation Code, and the Assessor issues a mandatory market-rent survey each December with an April 10 response deadline. Missing the survey can trigger investigation and County-initiated non-renewal.
When the parcel is right and the paperwork is heavy
Rural acreage in this county rewards buyers who treat the file, not the acre, as the asset. The four-agency sequence sounds intimidating on a first read, and it is exactly the kind of work an investor-minded broker who has closed on contracted land, well-permitted sites, and OWTS parcels can compress into a single timeline for you.
If you are under contract, or evaluating a listing before you write one, NAVJIT SANGHA will walk the diligence sequence with you, agency by agency, before contingencies become deadlines. Request your free home valuation, or a parcel-specific consultation, to start the conversation.
