Top image: Equinix Silicon Valley data center. Photo: Equinix, Inc. / CC BY-SA 4.0 via Wikimedia Commons

For two decades, the server farm was the quiet infrastructure of Silicon Valley’s success: windowless, humming, and mostly out of sight. In October 2026, it became the region’s most contested land use. Within a single month, governments from Brisbane to Santa Clara have moved to pause, study, or tighten the rules on data centers. Their concerns are the same ones now shaping AI’s next phase: power, water, and who pays.

San Mateo County: from a fairgrounds pitch to a possible ban

On Tuesday, Oct. 20, the San Mateo County Board of Supervisors will consider a resolution sponsored by Supervisors Noelia Corzo and Lisa Gauthier. It would direct county staff to study zoning rules for data centers on unincorporated land, including whether to ban them outright, Hoodline reported, citing the San Mateo Daily Journal. The resolution does not itself enact a ban. Any ordinance would come back to the board later.

The trigger was a proposal that went nowhere. In July, Santa Ana-based Global Stack LLC pitched eight Bay Area data centers, including one at the San Mateo County Event Center, as part of a plan covering 70 California fairgrounds. County Executive Mike Callagy said there was zero interest, and the idea was rejected. But it exposed a gap: according to the county staff report described by Hoodline, county zoning currently does not regulate the siting, construction, or operation of large-scale data centers on unincorporated land at all.

The county is not acting alone. Brisbane approved a 45-day moratorium on Oct. 1, San Francisco followed on Oct. 6, and Oakland adopted a similar pause this month, according to Hoodline’s summary of regional coverage.

Santa Clara: the data-center capital weighs its own limits

Santa Clara is where this fight carries real stakes. The city has 56 data centers plus two approved projects not yet under construction, San José Spotlight reported. On Oct. 6, the City Council voted unanimously to prioritize new water and air-quality standards for the facilities and ordered a broader policy review covering health, siting, and community benefits.

A proposed moratorium was not heard that night because the meeting adjourned at 1 a.m. Councilmember Karen Hardy told San José Spotlight she plans to bring it back on Oct. 20, focused on new standalone data centers. “I’m being very strident, but I was frustrated that we couldn’t even bring it to a vote,” Hardy said.

The tension comes down to electricity. Silicon Valley Power, the city-owned utility, stopped issuing “will-serve” letters in 2023. Even so, “we actually do have eight entities that went through the system impact studies, so they kind of made it through the process,” utility director Nico Procos told the council. Councilmember Kevin Park warned that developers can keep advancing land entitlements while they wait for power. “I would like to do a moratorium,” he said.

Water is the other lever. City officials said about 65% of Santa Clara’s data centers use recycled water and account for 26% of the city’s current recycled-water use. Existing rules require developers to maximize recycled water but set no numeric standard, according to San José Spotlight.

Sacramento sets the floor

Both local debates sit on top of new state law. On Sept. 21, Gov. Gavin Newsom signed seven data-center bills that his office called the most comprehensive in the nation. Two are by Assemblymember Diane Papan (D-San Mateo): AB 2469, on water-use disclosures, and AB 2619, on water resources. Another, SB 1168 by Sen. Jerry McNerney (D-Pleasanton), addresses data-center rate structures. According to the governor’s office, the package requires data centers to pay their share of grid-upgrade costs, to give water suppliers information on use, supply, and drought planning, and to qualify for judicial streamlining only after showing they won’t shift costs to ratepayers.

The long view

The pattern matters more than any single vote. In the 2010s, the Bay Area’s data centers were treated as an afterthought of the cloud. In the AI era, they behave more like heavy industry, with grid demands that local utilities and water agencies have to plan for years in advance. The jurisdictions acting this month are not rejecting technology. They are writing the first local rules for a new kind of industrial building.

For Silicon Valley, the irony is plain. The region that designs the chips may increasingly host fewer of the buildings that run them, and the debate is shifting from whether to build to where, on whose grid, and on whose water. Watch the Oct. 20 meetings in both Redwood City and Santa Clara for the next signal.

Sources

• Hoodline, “San Mateo County Weighs Data Center Ban After Fairgrounds Scare,” Oct. 16, 2026
• San José Spotlight (Maryanne Casas-Perez), “Santa Clara wants better water, air standards for data centers,” Oct. 11, 2026
• Office of the Governor, release, Sept. 21, 2026
• San Mateo County Board of Supervisors agenda, Oct. 20, 2026 (via DocketCity)