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 and that Meadowlake’s peak and off‑season flows complicate per‑capita calculations.

Commissioners and staff discussed technical trade‑offs. Staff cited the plant’s equalization basin and the difference between hydraulic capacity (handling short bursts of volume) and treatment capacity (removal of nitrogen, phosphorus and biochemical oxygen demand). Hanks said the plant has so far met monthly permit limits and that recent bioreactor performance has exceeded model expectations in nitrogen removal, but added that the city would re‑run facility capacity modeling after another year of observed performance.

The city also engaged a preliminary engineering reviewer to study conveyance, lift stations and transmission infrastructure; staff said upgrades to those systems — and to I&I (inflow and infiltration) controls — could change how much new development the system could accommodate. Hanks told the commission the city will likely pursue the state’s new utility development plan process if fall 2026 performance data supports it; that process, if approved by the DEQ engineering branch, could permit phased development that temporarily exceeds current capacity with conditions and capital improvements.

Pending and proposed developments were central to the discussion. Staff listed roughly 540 people of already reserved allocation and numerous active proposals (examples given in staff remarks included townhomes on 4th Avenue West, a larger Teakettle Heights proposal, Tamarack Meadows single‑family units, and a reapplication for apartments at 302 Meadow Lake Boulevard). Staff estimated committed and future applications totaling about 2,100 people — producing a deficit of roughly 1,200 people if the June 2022 peak is treated as part of capacity, or a much smaller deficit (about 200 people) if that month is excluded.

Public commenters urged both urgency and caution. Resident Mike Berg said excluding anomalous months could understate future risk, given changing climate patterns. Shirley of Shooting Star Drive asked whether the plant would overflow during a future high‑flow event; staff replied that the plant’s hydraulic systems and equalization basin prevent uncontrolled overflows and that monthly permit averaging allows for short peaks. Nathan Dugan, executive director of Global Flathead, urged the commission to weigh long‑term tax base and infrastructure costs when deciding whether to encourage annexation or encourage infill.

Commissioners asked legal and procedural questions about how current applications would be treated while the city clarifies capacity. Staff said the city can place incompletely submitted major subdivision applications on hold by issuing insufficiency notices pending capacity clarity. Several commissioners urged additional public outreach and clearer infographics tying capacity scenarios to housing and development outcomes before making policy changes.

Hanks also reviewed the land‑use planning calendar and outreach: the public survey had closed with about 244 completed responses, a consultant would produce an existing‑conditions draft for public review, and an open house on utility infrastructure was planned for February–March (dates TBD). Hanks said further joint council/planning commission sessions are scheduled in January and late January for additional review.

No formal policy decisions were made at the meeting. The commission approved the planning commission minutes from the Sept. 11 meeting by voice vote earlier in the session. The commission and staff agreed to continue working with engineers and DEQ, to refine capacity modeling, and to provide clearer public information before taking any final allocation or prioritization actions.