Pima County is trying to close a gap in its zoning rules before more large data-center projects can move through without public review. At a public video meeting Thursday, residents questioned the noise, water use and location of future facilities. County staff are preparing a code for a December vote, but it is not yet clear how the new proposal would affect projects already in the pipeline, KJZZ reported.
The proposal would add a public review process
Under the draft, data centers larger than 25 acres would be limited to CI-2 zoning, which covers about 2.3% of the county, and would need a Type 3 conditional use permit. That process requires two public hearings and approval by the Board of Supervisors. The county is developing the rules during a 120-day pause on new data-center development in unincorporated areas, approved by supervisors on September 22. The moratorium applies to projects that had not yet submitted permits, after supervisors amended its scope; it is expected to lift in January 2027, AZ Luminaria reported.
Noise drew the most attention at Thursday’s session, according to KJZZ. The draft would limit routine generator testing to weekdays from 8 a.m. to 5 p.m., with an emergency exception, and set an absolute noise cap of 75 decibels. Proposed setbacks from neighboring properties range from 100 to 200 feet. Staff encouraged residents to submit evidence-backed recommendations on buffers and sound controls. The draft also rules out open-loop cooling, calls for developers to show adequate water supplies and expresses a preference—but not a requirement—for clean energy. Newer diesel backup generators would be allowed if certified by the county’s Department of Environmental Quality.
Existing projects expose an unresolved boundary
The proposed code is not yet settled, and its reach over applications filed under older zoning is an open question. Project Gravel, a proposed campus near Sahuarita, predates the moratorium. Its developers are seeking administrative approval based on industrial zoning rights tied to a 1969 agreement for a former plant; county staff have not determined whether the new code would apply, Tucson Agenda reported. That uncertainty matters because the moratorium excludes projects that had already submitted permits.
The county’s rulemaking is also unfolding amid debate over Project Blue, a proposed data-center campus near the Pima County Fairgrounds. The county describes the project as a $3.6 billion, 2.25-million-square-foot development with a potential power demand of up to 600 megawatts. Tucson rejected Beale Infrastructure’s annexation request in August, after which the developer waived the annexation condition in its county purchase agreement, according to the county’s project FAQ and the Coalition for Sonoran Desert Protection. Project-specific decisions and the proposed countywide code are separate processes.
Nearby rules offer comparisons, not a template
Other Arizona jurisdictions have adopted or considered rules within their own boundaries, offering examples of different approaches rather than a single statewide standard. Chandler’s 2022 ordinance requires a third-party baseline sound study before a proposed data center’s first neighborhood meeting, according to the city ordinance. Tucson adopted separate city-limit regulations in August 2026 that include independent noise studies and compliance with its Large Quantity Water User Ordinance, AZPM reported. Those municipal requirements do not determine what Pima County’s proposed zoning code will require.
The county has received between 1,200 and 1,500 comments during the drafting process, most expressing general opposition rather than specific code recommendations, KJZZ reported. The draft and public input are scheduled to go to the Planning and Zoning Commission for an October 28 hearing, followed by an expected Board of Supervisors vote in December. The code remains a proposal; its final standards and application to projects with earlier filings have yet to be determined.
