Los Angeles County banned large-scale AI data centers from all unincorporated areas on Friday, Sept. 18, in a land-use action driven by health and environmental concerns raised by San Gabriel Valley residents.

Department of Regional Planning Director Amy Bodek issued the order in a memorandum directing staff to reject any new large-scale AI data center applications immediately. The directive serves as interim guidance while the county pursues a permanent change to its zoning code, Spectrum News reported.

Board of Supervisors Chair Hilda Solis, who represents the First District, set the ban in motion in April when she introduced a motion directing county departments to study data center impacts. The board unanimously approved the motion on April 14, launching a 120-day review.

"I introduced it in response to concerns raised by San Gabriel Valley residents who were understandably concerned about the effects of data centers in their communities, concerns that have since been reflected nationwide," Solis said in a statement.

Solis said she plans to bring a formal zoning code amendment before the board to make the ban permanent.

Why residents pushed back

Communities including City of Industry, Avocado Heights, Bell, Hacienda Heights and Rowland Heights raised alarms about proposed data center developments in their neighborhoods, according to the Daily News.

Mark Pestrella, director of LA County Public Works, said in April that a single large data center can consume up to 5 million gallons of water per day. If local agencies had to supply several facilities, they could be forced to buy more expensive imported water, raising consumer bills.

Barbara Ferrer, director of the LA County Department of Public Health, said in April that greenhouse gas emissions from U.S. data centers rose 48% since 2019. Large facilities rely on backup diesel generators that produce noise and air pollution, she said. Substations create a constant low-level hum that can affect health.

Rita Kampalath, the county's chief sustainability officer, warned in April that the added electrical demand could force utilities to run diesel-fueled "peaker plants," undermining the county's climate goals.

How the April moratorium was scaled back

The April motion nearly went further. Solis originally sought an immediate moratorium and directed County Counsel to explore legal action against data center construction. Construction unions pushed back, testifying that the facilities create jobs. That language was stripped before the board's unanimous vote.

Five months later, Bodek's memorandum delivers the prohibition Solis initially sought.

As of April, 74 data centers operated across Los Angeles County, with fewer than six classified as hyper-scale. Most sat in Vernon, El Segundo and Burbank. None were in unincorporated areas.

Monterey Park became the first California city to ban hyper-scale AI data centers earlier this year, according to Spectrum News.

No date has been announced for the board vote on a permanent zoning code amendment.