Aldermen amend St. Louis data-center zoning ordinance, send measure back to planning commission

The St. Louis Board of Aldermen on July 20 amended and deferred a comprehensive zoning ordinance for data centers after hours of debate over neighborhood impacts, renewable-energy rules and downtown activation.

Alderwoman from the 1st, sponsor of board bill 49, described the measure as a detailed new chapter to the zoning code meant to regulate data centers citywide. "As you'll read, we have information about this being adding a chapter to the zoning code specifically for data centers," she said, outlining definitions, a use table, application requirements and environmental review for major facilities.

Why it matters: supporters said the bill fills a regulatory gap — data centers have been treated as warehouses and can locate without clear conditions — while opponents warned about air quality, noise, and the risk of hollowing out downtown if too much space shifts to non-activated data uses.

What the ordinance would do: the sponsor said the measure sets tiers for micro, standard and major data centers; requires detailed applications that include site plans, maximum power demand, flood and environmental reviews for larger facilities; limits testing of backup generators on poor air-quality days; and requires public-impact agreements for major centers.

Amendments adopted on the floor changed several substantive points. Amendment 4, offered by the alderwoman from the 8th, created a mechanism for applicants to exceed the bill’s 30% cap on data-center floor area within 300 feet of an existing data center if they meet higher ground-floor activation metrics (a 100% net leasable ground-floor activation threshold in the amendment’s description) and enter a negotiated community-benefit agreement with the city. The proposer said the tool is intended to "make sure these things are implemented well" and to avoid vacant first floors downtown. Critics on the floor, however, said the change could erode the uniform 30% cap the planning commission proposed and risk proliferation of high-density data centers. After debate, the amendment passed by roll call.

The board also adopted amendment 5, pushed by the alderman from the 2nd, to create a documented waiver process if an electric utility is "verifiably unable" to supply the bundled renewable energy or renewable energy certificates the ordinance requires. "This bill requires 100% renewable energy for 10 years. This amendment does not change that," the sponsor said, while urging a process to address market or utility limitations. Opponents described the waiver as a potentially broad off-ramp that could undercut local emissions goals; the sponsor said the amendment includes documentation requirements, testimony from the utility provider and a decision by the Board of Public Service.

Another floor change, amendment 6, clarifies how the ordinance treats institutional campuses (including medical and research campuses) and allows micro or standard centers that exclusively serve such a campus under narrow conditions; critics said the language needs clearer drafting on when setbacks apply. That amendment also passed after debate.

Several aldermen emphasized the stakes for neighborhoods and downtown. One warned staff estimates showed a single unmitigated 30 MW data center at full operation could add substantially to industrial emissions; supporters said the ordinance’s renewable-energy, reporting and penalty provisions create enforcement paths.

Next steps: because several substantive changes were made on the floor, the sponsor asked that board bill 49, as amended, be placed on the informal calendar so the planning commission can review the revisions before the board takes a final vote. The board agreed and sent the bill back to planning.

Timing and procedural note: sponsor and city staff said the ordinance includes a built-in two-year review by the planning commission and severability language so unlawful provisions can be removed while preserving the rest of the code.