Special Notice / Hearing: None____
Vote Required: 4/5ths ___
To: Honorable Board of Supervisors
From: Supervisor Lisa Gauthier, District 4
Subject: Interim Urgency Ordinance Establishing a Temporary Moratorium on New or Expanded Data Centers
RECOMMENDATION:
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Adopt an Interim Urgency Ordinance of the County of San Mateo making findings and establishing a temporary moratorium on the siting, construction, conversion, and/or operation of new or expanded data centers within the unincorporated area of San Mateo County, to the full extent authorized under state and federal law.
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BACKGROUND:
The rapid advancement and adoption of artificial intelligence (AI) technology have fueled a corresponding surge in the construction of large-scale data centers needed to power these systems. As data center development accelerates, public awareness has grown regarding the potential environmental, infrastructure, and community impacts associated with these resource-intensive facilities.
In recognition of these concerns, Governor Newsom recently signed into law seven bills regulating the construction and operation of data centers. These include measures requiring data center projects to disclose and report water usage (AB 2619 and AB 2469) and ensuring that the construction of new data centers is subject to environmental review (SB 887). In his signing statement, Governor Newsom cited increased electricity and water demand, constraints on the electrical grid, and pollution as reasons for the new laws.
In addition to state regulation, the County has independent authority to adopt ordinances regulating the use of buildings, structures, and land to ensure compatibility among land uses; protect public health, safety, and welfare; address infrastructure limitations and public service capacity; and preserve natural, scenic, and agricultural resources. Pursuant to this authority, the County may regulate, restrict, or prohibit data centers within its unincorporated area.
At its October 20th, 2026 meeting, the Board of Supervisors initiated a process to develop a long-term approach to addressing the potential siting of data centers in unincorporated San Mateo County. Specifically, the Board directed Planning and Building Department staff to work with the County Executive's Office and County Attorney's Office to evaluate and prepare appropriate amendments to the County's Zoning Regulations.
Prior to the adoption of a long-term policy, an interim measure is necessary to ensure the County has sufficient time to complete its review without the submission or consideration of data center applications.
DISCUSSION:
The construction and operation of data centers, particularly those supporting artificial intelligence, can place significant demands on local energy and water resources. These facilities also have the potential to generate substantial environmental impacts, including noise and air pollution, and create land use and infrastructure conflicts that may adversely affect public health, safety, and quality of life.
In response to these concerns, several California local agencies have adopted temporary moratoriums or permanent restrictions on new data center development within their jurisdictions.
In July of 2026, the County received an inquiry from a developer proposing to site a new data center at the San Mateo County Event Center as part of a larger proposal that included constructing eight data centers across the Bay Area. The County did not pursue this proposal.
However, this developer inquiry highlighted that additional proposals to construct data centers within the County should be anticipated and that the County's current Zoning Regulations do not contain adequate provisions to ensure that the siting, construction, and operation of data centers are appropriately regulated to protect public health, safety, and welfare and address potential environmental and community impacts.
As previously directed by the Board, staff will evaluate whether data centers are an appropriate land use in any zoning districts within the unincorporated County. This review will require time for staff to assess the potential impacts of these facilities, consider appropriate regulatory options, and develop recommendations for the Board's consideration.
It is further recommended that the Board schedule a noticed public hearing within forty-five (45) days from adoption of the urgency ordinance to consider whether to extend the moratorium.
The County Attorney has reviewed and approved the proposed urgency ordinance as to form.
COMMUNITY IMPACT:
The proposed temporary moratorium will provide the County with an opportunity to evaluate the potential impacts of data center development and establish appropriate regulations to protect the health, safety, and quality of life of residents in unincorporated San Mateo County. The moratorium will help ensure that these facilities are not approved before the County has had an opportunity to fully evaluate their potential impacts and determine appropriate land use requirements.
FISCAL IMPACT:
There are no net County costs associated with adoption of the proposed urgency ordinance.