The Cheyenne Board of Public Utilities has stopped accepting industrial wastewater from data center fill-and-flush and closed-loop cooling operations after tracing a rare bacterium in the city's reclaimed water to Goat Systems LLC, the entity Meta uses to build its Cheyenne campus. In a notice reported by Cowboy State Daily, the Board said Goat Systems was in significant noncompliance for discharging water carrying Cupriavidus gilardii, a metal-resistant bacterium that interfered with two water reclamation plants and pushed the reuse system offline for months of cleanup. The Board revoked the contractor's fill-and-flush discharge privileges on March 24, and a wider suspension now covers every data center connected to city services.
Fill-and-flush is a commissioning step in which crews fill a cooling loop's piping with water, flush it to clear debris before the system is run, and then send the used water to drain. Goat Systems routed that flush water, which contained Cupriavidus gilardii, into Cheyenne's sanitary sewer, Frank Strong, the Board's engineering and water resource division manager, told the Wyoming Tribune Eagle. Strong said the fill water had been purchased from the Board itself and that the origin of the bacterium remains unknown, but said that lab staff caught it in February during routine fecal-bacteria sampling. "This isn't something we normally test for," Strong told the paper.
Microsoft and Nvidia market sealed liquid loops as a near-zero-water alternative to evaporative cooling, an approach that is spreading quickly as AI data centers expand into more communities. Microsoft describes cooling systems that are filled once during construction and then recirculate the same water, while Nvidia's Rubin platform runs a coolant that is 75% water and 25% propylene glycol. That one-time fill, however, is the step that produces a discharge, and the flush water leaves the site before the loop is sealed.
Strong went on to add that the Board's concern extends past the finding of the bacterium, because closed-loop systems can carry glycol and other chemicals that municipal treatment plants aren't built to process. Cheyenne sprays its reclaimed water on parks, golf courses, and other green spaces, and the Board worried the bacterium could become an aerosol hazard during irrigation. Cupriavidus gilardii isn't a regulated contaminant, yet the discharge disrupted treatment sufficiently to trigger pass-through and interference findings under the Cheyenne City Code and federal pretreatment rules.
Meta said that it's supporting its general contractor, Fortis, which stopped discharging and began hauling wastewater offsite, and that independent testing found no trace of the substance. Testing at the Dry Creek and Crow Creek facilities cleared in late June, and the reuse system is back online. Cheyenne City Councilman Pete Laybourn called the disclosure "a very, very unpleasant surprise." The Board hasn't said how the suspension affects other Cheyenne data centers still under construction.
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