Activists urge DEQ to consider public comment on proposed Big Sky subdivision 

‘Quarry’ to include 135 single-family homes near Gallatin River; planned transition from septic to sewer remains uncertain 

By Jack Reaney ASSOCIATE EDITOR 

Leaders from five nonprofit organizations sent a letter to Chris Dorrington, director of Montana Department of Environmental Quality, asking for DEQ to implement a public comment process for phase two of the Quarry planned unit development in Big Sky.  

The letter offers concerns for the nearby Gallatin River—listed as “impaired” in April 2023—primarily the impact of nutrient loading from the large-scale subdivision. At full build, the development would include 135 single-family homes, 130 apartments, and commercial spaces.  

The Quarry PUD was proposed in 2019. In December 2022, DEQ opened public comment on phase one of the project—the first 90 single-family homes. Activists are urging DEQ to repeat that process before approving a permit for phase two—the next 45 single-family homes—once the developers apply for a DEQ permit.  

Phase two was approved by Gallatin County commissioners on March 5, 2024. Phase two construction cannot begin until developers are granted a DEQ permit.  

Leaders from Upper Missouri Waterkeeper, American Rivers, Montana Trout Unlimited, Greater Yellowstone Coalition and Montana Environmental Information Center signed the letter, dated March 13.  

“The undersigned respectfully request the Department of Environmental Quality offer a formal public comment process regarding its forthcoming consideration of water, wastewater, and stormwater facilities associated with phase two,” the letter’s opening stated. 

Activists expressed concern that the Quarry’s phase two application is “notably deficient” in evaluating the impacts of wastewater on the Gallatin River, located about 1,200 feet to the east, downhill, across U.S. Highway 191. 

“The public has a right to understand how DEQ is studying the Gallatin River and its eutrophication challenges pursuant to its impairment determination, while simultaneously considering new development proposals that will contribute new water pollution loads linked to the same eutrophication events,” the letter stated.  

The Gallatin River’s impairment designation requires authorities to establish a “total maximum daily load” of pollutant nutrients that a river can withstand. 

The letter suggested that DEQ’s approval of phase two—which would eventually allow 11,250 gallons per day of wastewater treated with decentralized septic systems—without a transparent public process, would not reflect the “robust analysis of nutrient loading to the river” anticipated due to the river’s impairment.  

“… we call on DEQ to follow its established precedent and formally offer a public comment process regarding its consideration and proposed action(s) concerning Phase two of the Quarry PUD, just as it did for Phase one of this multi-phase subdivision,” the letter added.  

A response from DEQ was requested by March 29.  

Local developer: ‘we are going above and beyond’ 

Big Sky resident and developer Scott Altman represents Big Sky Rock, the development entity leading the Quarry project. On the phone with EBS on March 22, Altman clarified that DEQ did not issue a public comment period on phase two because Big Sky Rock has not yet applied for a DEQ permit.  

“When that does happen, we will have a public comment period,” Altman said. “We have to.” 

Altman pointed to numerous opportunities for public comment in the past, including a 45-day public comment period in 2022 after Big Sky Rock applied for a phase one DEQ permit. Having recently gained Gallatin County approval, the developers plan to apply to DEQ for phase two permitting in the coming weeks. 

If that phase two is permitted by DEQ after a public comment period, Altman is hopeful that construction on both approved phases of the Quarry PUD could begin this summer.

Altman emphasized that he lives near the Gallatin River and prizes its health.

He’s president of the newly formed Gallatin Canyon County Water and Sewer District, a project to improve wastewater treatment in the Gallatin Canyon portion of Big Sky. GCCWSD is currently annexing properties into a centralized sewer system, which, as planned, will pump water uphill into Big Sky’s brand new, $50 million Wastewater Resource Recovery Facility—the WRRF will raise Big Sky’s standard for wastewater treatment.  

If that GCCWSD effort is successful, as many as 156 Big Sky homes will no longer operate on septic systems. Altman said the canyon sewer district has received abundant buy-in and support from community members, the Gallatin River Task Force, and the DEQ.  

The Quarry project also plans to connect to that sewer system.  

When construction begins, homes will be constructed with “dry lines” down to the canyon floor. When the GCCWSD main is installed, the Quarry developers can attach those empty, unused pipes and simply “turn a valve,” Altman said.  

However, the GCCWSD is still in the engineering stage, and ironing out the feasibility of pumping wastewater uphill from intersection of U.S. Highway 191 and Montana Highway 64 (Lone Mountain Trail). It poses a chicken-and-egg situation for the Quarry PUD. 

“Our project is actually very integral to the canyon sewer,” Altman said. The financial feasibility of the sewer project may depend on adding ratepayers in the Quarry subdivision.

“You can’t have a system without customers. And you can’t have customers without a system.” 

If a forthcoming DEQ public comment period passes and the Quarry is granted a phase two permit, construction will begin with decentralized SepticNET systems. Each system can treat wastewater from about 20 homes, and the Quarry will install six systems by the end of phase two.  

SepticNET can reduce nitrate output to 3 to 5 parts per million, significantly lower than DEQ maximum of 20 ppm, Altman said. If all goes according to plan, they will be a temporary fixture—within legal requirements—until the canyon sewer line is operational.  

“All of our plans include hooking into [GCCWSD],” Altman said. “It’s much better treatment, it’s much better for everything we believe in.” 

Altman said the SepticNET systems will eventually be removed and transferred to existing developments further south in the canyon. He used Rainbow Ranch Lodge as an example of buildings and homes beyond reach of the new sewer district, where existing septic systems may be outdated and contributing nutrients to the river.  

“We personally feel like we are going above and beyond,” Altman said. “… There’s going to be development at some point, and I think responsible development is the key.”  

Now, main concerns surround the uncertainty of that new water and sewer district. If phase two is fully permitted and construction begins, and if the GCCWSD effort falls through, then 135 additional households could be stuck on septic treatment beside a river that is already impaired.

Before approving phase two on March 5, Gallatin County commissioners expressed concern about that scenario, according to reporting from Bozeman Daily Chronicle.   

However, if the canyon sewer district is constructed with success, the Quarry—plus existing homes and commercial structures in the area—will be pumping wastewater to a state-of-the-art treatment facility.  

“All those concerns pretty much go away,” Altman said.