As a retired scientist who has conducted water quality studies in Flathead Lake for over 30 years, I was deeply concerned by the decision made at the August 21 Lakeside County Water and Sewer District Board meeting. The board voted to move forward with an older, less efficient design for their new wastewater treatment plant—a choice I believe could threaten the water quality of Flathead Lake.
Three design alternatives were presented: oxidation ditch, sequential batch reactor (SBR), and membrane bio-reactor (MBR). Regrettably, the board selected the SBR system. I believe this decision was heavily influenced by their advisory engineers and the district’s general manager, who strongly advocated for the SBR based on lower construction cost and operational simplicity. Unfortunately, they gave the misleading impression that all three options would produce similar water quality.
That is simply not the case.
In the recent guest column in The Flathead Beacon, officials from the Flathead Lake Biological Station explained the major improvements in water quality following their recent upgrade from an SBR to an MBR system. The new MBR facility with alum tertiary treatment has reduced phosphorus levels to as low as 0.01 mg/L—more than a 20-fold reduction over their former SBR plant.
In stark contrast, materials presented by the Lakeside advisory engineers show a target phosphorus effluent level of 1.2 mg/L for the new SBR plant—over 100 times higher than the phosphorus output now being achieved by the MBR system at the Biological Station. This elevated target value for phosphorus is especially alarming given that several experts have raised concerns about the proposed infiltration basins—and adjacent network of shallow sand aquifers, interconnected wetlands, and sloughs—that are poorly suited to further reduce phosphorus levels removal once the treated water leaves the plant and makes its way to Ashley Creek and nearby Flathead Lake.
When board members raised concerns about water quality, the engineers gave vague or evasive answers. One member asked, “Of the three design options, which one has the cleanest water output?” The engineer did not provide a direct answer. Another asked, “We’re a mile from the lake—will that affect the choice between SBR and MBR?” The engineer responded, “No, they will all put out the same water quality to meet the permit.”
A board member later questioned whether the SBR was still considered state-of-the-art. The engineer replied, “If there is something state-of-the-art, it’s probably the MBR,” and even acknowledged, “Here, I think it [MBR] would work well.” Still, the conversation returned to cost: “It’s more costly, and there are more operational costs.” The engineer later added, “We wouldn’t want to be on the cutting edge.” But the MBR is hardly experimental—it’s already in use not only at the Biological Station, but in Butte, Big Sky and nearby Bigfork, where it was installed as early as 2010.
Unfortunately, no public comment or questions were allowed during the board discussion or prior to the vote; however, public comment was allowed earlier in the meeting at which time I advocated for the MBR design due its’ superior effluent quality. A number of others spoke to the importance of protecting water quality in Flathead Lake.
Just before the final vote, District Manager Rodney Olson gave his final recommendationendorsing the SBR design because it was the cheaper and less complex to operate than the MBR design—aligning with the engineers’ final recommendation.
By the end of the discussion, it became clear that both the engineers and district manager had given the board an incomplete—and in some cases—misleading impression—that all three designs would produce similar water quality. That is simply not true.
In the end, the board selected the SBR system because it was cheaper and easier to operate—not because it offered the best protection for Flathead Lake. Disturbingly, two of the five board members were not present for this critical discussion and vote.
As others have urged in recent editorials, I strongly encourage the board to reconsider. Instead of choosing the cheapest option, I urge them to choose the one that produces the cleanest effluent. That would be the MBR system—with alum tertiary treatment.
Even better, in my view, would be to follow the example set by Lake Tahoe. Faced with increasing development and mounting water quality concerns, the communities around Lake Tahoe united in the 1970’s to remove treated wastewater from the basin entirely. They built a system to pipe effluent out of the watershed to areas less sensitive to nutrient pollution—an innovative approach that helped protect one of the clearest lakes in the world. A similar approach was taken at Lake Washington near Seattle.
For Flathead Lake, a comparable long-term solution might involve piping effluent over the divide to the west or to the Lower Flathead River below Kerr Dam. It would be a bold move—a move that reflects the importance of protecting Flathead Lake’s exceptional water quality for future generations
Flathead Lake is one of Montana’s most precious natural resources. We must not compromise its future for short-term savings or operational convenience. Let’s choose a path that puts water quality—and the lake itself—first.
Dr. Craig Spencer is a retired professor of freshwater ecology who previously worked at the Flathead Lake Biological Station and Augustana University.