City staff warns wastewater capacity limits could curb development; public urged fuller outreach

City staff told the Columbia Falls Planning Commission that new engineering analyses and a June 2022 high‑flow event have reduced the city’s effective wastewater treatment capacity and could limit near‑term development approvals.

Eric Hanks, a member of city staff, summarized the technical background. He said HDR’s February 2023 analysis lowered the plant’s bioreactor design capacity from about 0.85 million gallons per day (MGD) in 2017 to roughly 0.63 MGD, and that subsequent design updates project a post‑expansion capacity around 0.7–0.71 MGD. “In that study, they lowered our bioreactor capacity to 0.63,” Hanks said. He told commissioners that how the city treats the June 2022 extreme rain event — whether it is included as a normal month of flow or excluded as an anomaly — changes the population the plant can support by several hundred to more than a thousand people.

Hanks said the 2023 basis of design, modeled with BioWin software, estimated a 0.7 MGD facility could serve about 8,174 people; using a lower 0.63 MGD assumption reduces that number to about 7,392, a difference of roughly 780 people. He also noted that the Meadowlake Resort and Meadowlake Water and Sewer District are included in some baseline counts…