Flathead Lake is one of Montana’s most valuable natural resources, and protecting its water quality has been the mission of the Flathead Lakers for more than 67 years. Today, we are concerned that recent decisions by Flathead County, the Lakeside Water and Sewer District, and the Montana Department of Environmental Quality (DEQ) may put that legacy at risk.
We are not opposed to growth. The population around the lake is increasing, and expanded wastewater treatment is necessary. But those systems must be designed and operated in a way that fully protects the lake and its watershed.
The current plan for a new treatment facility raises serious questions—particularly regarding the handling of septage, the concentrated waste removed from tens of thousands of septic systems across Flathead County. Septage contains elevated levels of nutrients such as nitrogen and phosphorus, along with contaminants including PFAS (“forever chemicals”), heavy metals, pharmaceuticals, and microplastics. Managing these materials safely is a growing and unavoidable challenge.
In 2021, Flathead County began seeking solutions for septage disposal. Its stated approach was to treat septage to domestic wastewater standards and then partner with an existing wastewater district for final discharge. As county officials noted at the time, they intended to be “a client, not a discharger.”
That distinction mattered. It meant the county would remain responsible for adequately treating this high-strength waste before it entered another system.
After struggling to find a partner, the county ultimately reached an agreement with the much smaller Lakeside Water and Sewer District, whose existing facility already required upgrades to meet increasing demand. Under the original understanding, the district would accept septage only after it had been treated to domestic wastewater standards.
That plan has since changed. The county now proposes delivering untreated septage to the Lakeside facility, shifting responsibility for managing a more complex and concentrated waste stream onto a system not originally designed for it.
At the same time, DEQ approved a Phase 1 expansion of the treatment plant without fully addressing how septage will be handled in later phases. The proposed system relies on discharging treated effluent into shallow groundwater in the Lower Valley, where the water table can be less than ten feet below the surface—raising legitimate questions about how effectively contaminants can be contained before reaching Flathead Lake.
DEQ’s analysis focused primarily on nitrogen and phosphorus, concluding that natural soil processes would reduce nitrogen over time, and that Phosphorus would not reach the lake for 30 years. However, an alternative report prepared by highly regarded stream ecologist Ric Hauer of the University of Montana, identified significant flaws in that analysis and suggested that contaminants could move through the system much more quickly—potentially reaching the lake in less than a year.
Despite receiving this analysis, DEQ did not meaningfully address it in its Environmental Assessment. Nor did it evaluate the potential impacts of adding untreated septage to the system, deferring that question to a future phase.
This sequence of decisions—changing the nature of the waste stream, advancing project approvals in phases, and narrowing the scope of environmental review—has left critical questions unanswered.
Flathead Lake is exceptionally clear today because of decades of careful stewardship and sound policy decisions. That clarity should not be taken for granted. Once degraded, water quality is extraordinarily difficult and costly to restore.
We believe this project deserves a more complete and transparent evaluation before moving forward. That includes fully accounting for how septage will be treated, how contaminants will move through groundwater, and how conflicting scientific analyses are being weighed.
Montana has long prided itself on balancing growth with conservation. Getting that balance right requires taking the time to fully understand the risks before decisions are locked in.
Flathead Lake is too important to do otherwise
Coby Gierke is the executive director of Flathead Lakers.