Missoula County staff outline review process as community debates proposed Bonner data center

Missoula County planning staff told the Bonner Milltown Community Council on June 8 that they have received a new, substantially different application to repurpose part of the Bonner mill site as a data center and expect to publish an analysis and questions to the applicant once their review is complete.

"We have received another application for review. It is pretty drastically different," said Jenny Dixon, a case planner with the Missoula County Planning Department. She said the county hopes to complete an initial staff assessment by the end of the week and will post documents to Missoula County Voice.

The filing contains two technical changes that staff highlighted. First, the applicant has shifted from a mix of evaporative and adiabatic cooling towers to a primarily adiabatic system with an evaporative backup. County staff said that change reduces routine water use but raises questions about how often and under what conditions the backup evaporative cooling would operate. Second, staff said the application now contemplates backup generators (diesel or natural gas) should the project be unable to secure sufficient backup power from the local utility; staff said they would request modeling on air quality and noise impacts related to any backup generation.

"The most notable change is the proposed shifting from a mix of evaporative and adiabatic cooling towers to all adiabatic but with an evaporative backup," county staff said. They added the filing also provides more detail on potential backup generators and their expected use.

Staff told the council the current application proposes a 7-megawatt facility; the site infrastructure could support larger future build-outs (staff said the site has infrastructure for up to 29 megawatts), but any expansion beyond 7 MW would require additional review. "Anything over seven will have to come back for this process," staff said.

Water use was a recurring concern. County staff summarized available water rights for the mill site at roughly 330 million to 404 million gallons per year and said the existing mill uses about 2 million gallons per year. The applicant’s last filing estimated that, under the adiabatic approach, the 7-MW buildout might use as little as about 5,000 gallons per year, while an evaporative system variant would have required tens of millions (17–22 million gallons); staff said an evaporative backup scenario included an upper cap of 1 million gallons per year proposed by the applicant and a public meter and cap in that filing.

County staff emphasized the application is not yet administratively complete. "We were projecting dates assuming completeness, but at this point it would just be better to take those off completely until we have more information," said Jenny Dixon, urging residents to watch Missoula County Voice for updates. Staff estimated roughly seven weeks as a minimum interval between a complete application and a hearing, noting legal notice requirements (a 15-day legal notice and an effort to mail notices at least 30 days ahead to residents within 500 feet).

Because the proposal lies within 500 feet of residential property, the county attorney’s office advised staff that the special-exception review must consider the full range of impacts listed in the zoning criteria—not only direct residential effects. That broader scope includes natural-resource impacts, utilities, noise and vibration, lighting, and other community-relevant factors staff identified.

Residents pressed staff about specific risks. Questions included where cooling fluids and glycol waste would be handled, whether toxins or persistent chemicals could reach rivers and aquifers, and how many hours of backup-generator operation the facility might need. Staff said they are seeking more detail from the applicant and do not yet have definitive answers.

The meeting included an extended public comment period in which dozens of residents weighed in. Several speakers urged rejection on environmental and community-impact grounds; others urged rigorous modeling and enforceable conditions if the project proceeds. One land-use question asked whether the county could impose measurable thresholds—for example an ambient-temperature limit tied to a monitoring and enforcement plan—and staff said conditions of approval can be written and monitored, though they noted the county had not previously used numeric ambient-temperature thresholds and is working through how to address novel impacts.

The applicant is listed on filings as Cranoo EM LLC, with Steve Wood named in county documents as a company lead; earlier filings were submitted by contracted engineer Gordon Dobler, staff said. County staff also said no lease agreement with the property owner had been signed at the time of the meeting.

Next steps: the county will continue its completeness review, publish staff questions and its analysis on Missoula County Voice, and schedule a Land Use Board hearing only after the application is administratively complete and legal notice requirements are met. The earliest feasible hearing date staff mentioned was Aug. 5, but staff declined to commit to that date pending completeness.