State engineer, cities and companies debate data‑center water use; committee hears produced‑water options

The Select Water interim committee turned to consumptive water use and data‑center siting on May 7 in Cheyenne, hearing technical and policy testimony from the State Engineer, a University of Wyoming produced‑water researcher, and multiple data‑center operators.

Brandon Gart, Wyoming State Engineer, told the committee that consumptive use includes water diverted that does not return to the system — agriculture is the dominant consumptive category in Wyoming, with irrigation consumptive use typically ranging from about 1.3 to 2.5 acre‑feet per irrigated acre depending on region, crop and soils. He said municipal consumptive use is modeled as diversion minus return flows (treated wastewater), and that industrial uses can be consumptive when water is incorporated into products, evaporated (thermal power), or exported from a basin.

Gart explained permitting rules: any beneficial use requires a permit under Title 41; byproduct water (water produced as a byproduct of oil/gas or mining) is defined in statute and may be appropriated if intercepted before commingling, but a groundwater permit would be required to put it to beneficial use. He said permits that exceed 50 gallons per minute or 20 acre‑feet per year typically include metering and reporting requirements. Gart also reported the office currently has exploratory test‑well applications for hyperscaler projects (Prometheus in Evanston) recorded as exploratory with zero appropriation; he also said one Tallgrass initial well application requested 600 gpm and 967 acre‑feet and that some Tallgrass test wells have been converted to time‑limited miscellaneous use permits expiring in 2030.

Dr. Jonathan Brandt, director of the university’s Center of Excellence in Produced Water Management, outlined the scale and chemistry of produced water, treatment hurdles (residual hydrocarbons and salts), the energy and waste management challenges with desalination, and the economic opportunity of critical‑mineral recovery (e.g., lithium). Brandt emphasized logistics — Wyoming’s produced water volumes are large but geographically distributed — and said reuse for industrial cooling or municipal supply requires careful analysis and, in many cases, significant treatment investment.

Mayor Patrick Collins (Cheyenne) described his city’s experience: Cheyenne has hosted data centers for nearly 20 years and currently has multiple campuses. He said the 13 operating data‑center halls in Cheyenne use about 200 acre‑feet of water annually in total; under current closed‑loop technology and projected build‑out the city estimates roughly 400 acre‑feet per year — about 1.8% of the city’s cited 22,000 acre‑foot firm yield. Collins said Cheyenne requires developers to "do no harm," to pay for infrastructure and to use efficient cooling technology; the city limits evaporative cooling and expects closed‑loop or direct‑to‑chip systems.

Industry witnesses outlined technology and commitments. Jonathan Noble (Microsoft) said modern designs are moving to direct‑to‑chip liquid cooling and closed‑loop systems that, once charged, do not continuously evaporate water for cooling; he said Microsoft’s Wyoming facilities use evaporative cooling "less than 10% a year" and the company invests in local water replenishment and infrastructure projects. Prometheus representatives (Mary Throne and founder Trenton Thornox) described liquid glycol‑based closed‑loop systems that are filled one time with a propylene‑glycol/water mixture (PG‑25), circulated for multiple years (presenters cited about a six‑year turnover), and then polished and returned offsite by suppliers; they emphasized on‑site power self‑generation for some projects and trucked logistics for initial fills and maintenance.

State Engineer Gart told the committee that the statutory industrial siting review requires a water supply and yield analysis if a facility plans to use more than 800 acre‑feet per year; the SEO will issue a preliminary opinion that is published for public comment under statute (cited in testimony). The office also enforces metering/reporting for groundwater permits exceeding thresholds and retains authority to require monitoring in basins with interstate obligations.

Public commenters were sharply divided. Several urged caution and called for clear consumptive‑use accounting before allowing large new withdrawals, citing out‑of‑state cases where cooling solutions required more frequent fluid handling or generated unexpected discharges. Industry representatives and local officials countered that modern closed‑loop designs materially reduce annual consumptive use, that Cheyenne’s local experience shows modest aggregate demand compared to municipal supplies, and that companies will pay infrastructure costs and seek sites where utility capacity and water availability meet local policy expectations.

Why it matters: large hyperscale projects attract attention because they combine heavy power demand with potential industrial‑scale water use; in an arid state, accurate accounting of consumptive use — not only withdrawals — is essential to protect downstream users and aquifers.

Next steps: the State Engineer’s office continues to process exploratory well permits and time‑limited authorizations; the SEO will review any proposed industrial siting that seeks more than 800 acre‑feet per year and publish a preliminary opinion for public comment. Committee members asked staff to continue monitoring permit activity and to consider whether additional reporting or statutory adjustments are needed to assure transparent consumptive‑use accounting at the point of operation.