Where a San Mateo County data center ban would actually bite

On Edison Way in North Fair Oaks, a wood fence runs along one side of the street. Behind it are low metal buildings, roll-up doors and the old rail line. Across the double yellow line are small houses with picket fences and big oaks.

San Mateo County's zoning code lets a server farm go in behind that fence with no use permit at all.

On Tuesday, Oct. 20, the Board of Supervisors will be asked to start writing rules that could ban new data centers across every unincorporated part of the county. Supervisors Lisa Gauthier and Noelia Corzo sponsored the resolution, file 26-853. Gauthier's district includes North Fair Oaks, where Houseberry data puts the typical home at about $1.72 million in September 2026.

This is a story about where a ban would actually land. For most of the 63,164 people who lived in unincorporated San Mateo County at the 2020 census, from Montara to Ladera, a data center was never coming. In North Fair Oaks, the code already has the door open. That is the line we would fix first.

A fairgrounds pitch started this

In July, a company called Global Stack LLC pitched small "edge" data centers at eight Bay Area fairgrounds, the San Mateo County Event Center and the Cow Palace among them, SFist reported. Each would draw up to 10 megawatts. The plan came with parking garages and helicopter pads, and the company wanted to reach 70 California fairgrounds by 2030.

County Executive Mike Callagy said the county had no interest in a data center at the Event Center, and the idea died quickly, according to Hoodline. Corzo, whose district includes the fairgrounds, said she never supported it but that it started a needed conversation about local power and water.

Here is the part most coverage skipped. The Event Center sits on Saratoga Drive inside San Mateo city limits. The Cow Palace is a state-run venue in Daly City. A county zoning rule written for unincorporated land reaches neither one. What stopped the fairgrounds pitch was the county saying no as the landowner.

What the supervisors are actually voting on

The staff memo runs about a page. It asks Planning and Building, working with County Executive Mike Callagy's office and the county attorney, to "consider and prepare" zoning amendments, and it names a countywide ban on new data center construction in the unincorporated area as one option. The reasons it gives are energy and water strain, noise, air quality and conflicts with neighboring uses. It names no site and no applicant. The cost to the county is listed as none.

That makes Tuesday a starting gun.

A real ban would come back as a separate ordinance. If supervisors want something faster, state law already offers it: Government Code 65858 lets a county adopt a 45-day freeze by a four-fifths vote and extend it to as long as two years. Brisbane's council passed its moratorium unanimously on Oct. 1. We covered Oakland's pause the week San Francisco froze new projects too.

North Fair Oaks is where the rule has teeth

North Fair Oaks is the unincorporated pocket between Redwood City, Atherton and Menlo Park, built around Middlefield Road. The county wrote two industrial zoning districts just for it. One covers the blocks north of Fair Oaks Avenue around Spring Street. The other covers the strip between Edison Way and the rail tracks, from Fifth to 12th avenues, per the county's rezoning page.

Both chapters list "Server Farms" as item 6 under light manufacturing and storage, and the permit column says "None." That is in the county's own code text for the North Fair Oaks district. A builder would still need a site development permit, which covers design and site layout. What it skips is the use permit hearing, the one place neighbors get to argue about noise, generators and trucks.

The parking table asks for one space per 2,000 square feet of server farm. Nobody wrote that number with a 10-megawatt hall in mind. It reads like a rule for a back-room server operation from the dot-com years, and it is still on the books.

The homes closest to the industrial blocks

Houseberry scores North Fair Oaks 3.0 out of 5 overall, with 2.9 for safety, 2.9 for schools and 3.4 for amenities. Its typical home price of about $1.72 million in September 2026 is roughly 48 percent below the Menlo Park city figure of about $3.3 million that month. That gap matters on Edison Way. Of the seven unincorporated San Mateo County neighborhoods where Houseberry tracks prices, only Broadmoor sells for less. The places with the most to lose from a big industrial neighbor are the ones the code already exposes.

Houseberry files several of these under a neighboring city's name, so Emerald Hills appears with Redwood City and Ladera with Portola Valley. All seven sit on county land. The Coastside towns of Montara, Moss Beach, Princeton, El Granada and Miramar score 4.4 to 4.5 on safety but have no zoning that invites a server farm.

Fix the North Fair Oaks line first

We think the supervisors should vote yes on Tuesday. Then they should start with one line of the North Fair Oaks code.

Taking "Server Farms" off the no-permit list in North Fair Oaks does most of the real work a countywide ban would do, and it does it on the blocks where homes sit across the street. The Edison Way district also allows live-work units. Land next to the tracks in a neighborhood this close to Redwood City's Caltrain station is better spent on homes and shops than on a windowless building full of servers.

The honest trade-off is that a ban written too broadly could catch things nobody means to ban. A lab's server room, a telecom switch building and a hospital's backup computing all store data. The county should define a data center by power draw or floor area so the rule hits a 10-megawatt hall and leaves a closet alone. San Jose went the other way and wrote a 55-decibel noise limit instead of a ban. And the evidence on whether data centers hurt nearby home values is thinner than either side claims.

Staff will come back with a draft months from now. Until then, North Fair Oaks is the one neighborhood in unincorporated San Mateo County where the answer to "could a data center go in down the street" is yes, and you can see how it stacks up against 199 other neighborhoods on our Peninsula ranking.

Sources

• San Mateo County Board of Supervisors, file 26-853 staff memo, Oct. 20, 2026 agenda
• San Mateo County Zoning Regulations, M-1/NFO district chapter
• San Mateo County Planning, North Fair Oaks industrial mixed-use rezoning
• SFist, Global Stack fairgrounds proposal, July 9, 2026
• Hoodline, San Mateo County weighs data center ban, Oct. 16, 2026
• MTC and ABAG, unincorporated San Mateo County census profile, 2020
• City of Brisbane, moratorium news release