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Water Wisdom: Understanding wastewater treatment across Big Sky

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By Kristin Gardner and Karen Filipovich EBS CONTRIBUTORS

Turn on the shower, order a meal or flush the toilet. All of these activities involve water going down the drain. In Big Sky, what happens next and the resulting quality of treated water varies significantly depending on the type of wastewater treatment system. 

Wastewater treatment infrastructure varies in the Big Sky area from single septic systems to large, centralized systems. Wastewater treatment removes solids, pathogens and nutrients. Doing so protects human health and safeguards water supply and water quality.

Septic systems are designed for small, individual sites in areas with low density development. They are commonly found in the more remote areas of Big Sky, like the Gallatin Canyon or Beaver Creek. With this system, a tank settles out solids and bacteria digest nutrients and pathogens and the resulting effluent is then usually released into a drainfield.

There are two major types of septic systems: Level 1 and Level 2. Level 1 systems are more common and easier to operate, but do not remove as many nutrients as other methods. Typically, this system treats effluent to a point where total nitrogen concentration is about 50 milligrams per liter. Level 2 systems treat to a higher level, and are required to remove total nitrogen to a concentration of less than 24 milligrams per liter.

Level 2 systems are significantly more expensive than Level 1 systems and are more difficult to operate. However, these treatment levels are only achieved if a system is properly maintained. The individual landowner has complete responsibility of the system including any maintenance and testing.

Public wastewater treatment systems vary greatly in size and treatment methods around Big Sky, ranging from systems servicing a single business, to large groups of residential and commercial development. In Big Sky, these systems range from large onsite systems that are similar to individual septic tanks but serve multiple households or businesses, to treatment lagoons and multistep technologies. Treatment levels vary greatly based on technology, but all public systems require routine monitoring and reporting to the state.

The largest public wastewater treatment plant in the area is the Big Sky Water and Sewer District, which services the Meadow and Town Center areas, the Big Sky Resort base area, and parts of Spanish Peaks. The district’s facility is a tertiary treatment plant and achieves treatment levels similar to most of the smaller community treatment systems in Montana. The treated effluent’s total nitrogen ranges from 4 to 35 milligrams per liter depending on the time of year. The district is in the process of designing an upgrade and expansion that would achieve nitrogen concentrations of less than 5 milligrams per liter, similar to the Bozeman wastewater treatment plant and compliant with Montana’s Class A-1 reuse standards, the highest quality described by the Montana Department of Environmental Quality.

Improving wastewater treatment levels is very important as Big Sky grows because more effluent will be generated as more people move in and visit the area. Higher treatment levels also allow for more diverse reuse options for the treated water, which could be greatly beneficial to watershed health.

Kristin Gardner is executive director of the Gallatin River Task Force. Karen Filipovich is a facilitator and consultant in the Bozeman area.


Wastewater treatment in the Gallatin Canyon:

Gallatin Canyon Project Kickoff Meeting

Sept. 19 at 6:30 p.m.

Buck’s T-4

Canyon residents and business owners are invited to learn more aboutan engineering study that will provide information about wastewater treatment upgrade options in the Gallatin Canyon. This study is administered by the Gallatin River Task Force and funded through the Big Sky Resort Tax. Contact Karen Filipovich at or for more information.

Big Sky Water and Sewer District wastewater reclamation upgrades:

Big Sky Water and Sewer District –

Septic permitting and maintenance:

Gallatin Health Department –

Madison Health Department –

Gallatin Local Water Quality District –

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