Large-scale AI data centers would be banned from all unincorporated Los Angeles County land under a motion the Board of Supervisors is set to vote on Wednesday, Oct. 7.

The proposal by Supervisor Hilda Solis, who chairs the board, would direct the Department of Regional Planning to draft a zoning amendment to the county code. Planners would define "large-scale" data centers based on acreage, square footage, energy use and water consumption, then prohibit them in every unincorporated zone.

Smaller operations would not be affected. The motion distinguishes hyperscale and AI-focused facilities from what it calls "beneficial use" data centers, including enterprise and accessory facilities used for routine computing, according to the Westside Current.

The ban would not apply to incorporated cities such as Los Angeles, El Segundo, Santa Monica or Beverly Hills. Unincorporated areas that could be affected include Marina del Rey and parcels near Malibu and the Santa Monica Mountains. About 1 million of the county's 10 million residents live in unincorporated territory.

No data centers currently operate in unincorporated county land, though about 74 are running elsewhere in Los Angeles County, the LA Daily News reported.

The motion builds on months of county action. The board unanimously directed departments to study data center impacts in April. Mark Pestrella, director of county Public Works, told supervisors then that a single hyperscale facility can use up to 5 million gallons of water per day. Barbara Ferrer, director of the Department of Public Health, warned that the constant low-frequency hum from such centers "can create in some people a sensitivity that can create health impacts."

On Sept. 17, Planning Director Amy Bodek invoked existing authority to halt large-scale data center development while the permanent amendment takes shape.

Solis said in a September statement reported by Spectrum News that she introduced the April motion "in response to concerns raised by San Gabriel Valley residents who were understandably concerned about the effects of data centers in their communities."

The motion also directs the Department of Public Health and County Counsel to evaluate whether county noise rules should cover the low-frequency drone of large data centers. The county's chief executive officer would identify funding for the zoning amendment, the required California Environmental Quality Act (CEQA) review and any noise-regulation changes.

If a proposed project poses what the motion calls a "current and immediate threat to public health, safety, and welfare," Regional Planning and County Counsel would be prepared to impose a moratorium, the SGV Tribune reported.

Not everyone supports a ban. George Bocanegra of the Western States Regional Council of Carpenters, representing 12,000 members in LA County, told the board in April that "These data centers provide valuable opportunities for high-paying jobs." Joe Sullivan of IBEW Local 11, which represents 12,000 union electricians, said a ban would cut hundreds of jobs per site.

The board received 101 pages of public comments on the motion, most calling for a moratorium. Community opposition to data centers has been building across the region. On June 2, 86% of Monterey Park voters approved a ballot measure banning data centers. In El Segundo, a proposal to convert a Hyatt Place hotel into a five-story AI data center was withdrawn after more than 100 residents packed a Planning Commission meeting.

The county's planning department page tracks the zoning amendment process.