Gallatin Canyon

What does the future hold?

Cleaning Up the Canyon

The Canyon area of Big Sky features some of the most beautiful stretches of water on the Gallatin River. From fly fishing to floating, it offers endless recreation and stunning scenic views.

As this area developed, more and more individual septic systems came online, managed primarily by small public water operators. This decentralized approach to wastewater management has negative impacts on water quality, as nutrients from inadequately treated effluent seep into the groundwater, and then to the Gallatin River.

To protect water quality in this stretch of the Gallatin, the Task Force has long advocated for a Gallatin Canyon Water and Sewer District. In January of 2021, such a district was formed by four Canyon landowners—the Conoco service station, Lazy J, Scott Altman, and Buck’s T-4.

This new district is a huge step forward toward centralized wastewater treatment in the Canyon. Importantly, by forming a district, the Canyon landowners will now be able to connect to Big Sky’s new, state-of-the-art wastewater treatment plant, once it comes online in 2022.


A timeline for central water system is contingent on many factors, including the construction of Big Sky’s new facility and pipeline construction that would connect Big Sky to the Canyon. Because of this, it is likely that Gallatin Canyon residents are still several years away from central water and sewer.

For now, only the above mentioned landowners are included in the Gallatin Canyon district, but in the future, ideally more landowners and businesses will connect, cleaning up the Canyon before septic system pollution reaches a tipping point.


Frequently Asked Questions

What are the study boundaries?
From approximately 0.2 mile north of the highway 64 turnoff to the Corral/Rainbow Ranch area along the Gallatin River to the south.
Could the Canyon area be annexed into the Big Sky County Water and Sewer District (BSCWSD)?
• Yes, potentially, but the BSCWSD has no mandate to annex the Canyon Area without the Canyon Area forming a District and requesting annexation negotiations.
Will this study include projected growth?
• Yes. All engineering planning studies include growth rate estimates, typically for 20- or 30-year design timeframes. Growth rates in the Big Sky Area are typically much higher than for more developed communities (e.g., 5 to 6% versus 1 to 3%).
How is a District formed?
A District can be formed by a petition from 100% of landowners within a proposed boundary or through a vote of residents within a boundary.
How does a District work?
• More information can be found on the Montana Code Title 7 Chapter 13 Part 22 regarding county water and/or sewer districts.

• The District’s operation would be nearly identical to the BSCWSD, with an elected Board holding public meetings and voting on action items.

Can boundaries of the canyon move?
• Yes, the initial map was based on a 2008 study. Feedback will be sought from residents on options and The boundaries and options for wastewater solutions, whether it be for the entire canyon area or divided into smaller areas (“distributed systems”), will all be addressed in the study.
What are the advantages of forming a District?
Infrastructure funds from both 1% for Infrastructure Tax and the 3% Resort Tax provisions are open to Water and Sewer Districts. Other funds from state and federal sources are also only available to Districts. It also shifts liability from individual property owners to the District.

Per the current language on the May 5th ballot, the 1% for Infrastructure funds are only available if a Canyon District is formed by December 31, 2022.

What are the funding sources available?
• If the residents in the region form a District, funding options can include state and federal funds. They can also apply for resort tax funding. In 2019, the Montana State Legislature provided resort communities the opportunity to pursue an additional one-percent resort tax to be used strictly for infrastructure projects.
Will the report give a range of options?
• Yes, the final report will provide options, including a fully centralized sewer and a hybrid of centralized and decentralized systems. The plan will also include opportunities to phase the projects.
What happens with development if we do not form a Canyon Area District?
• Development will likely proceed in an ad-hoc way, with decision-making made by the Gallatin County Planning and Zoning Commission or Gallatin County itself.
Could the Canyon simply join the existing Big Sky Water and Sewer District by annexation?
While it is possible, it would require a vote of the existing District plus those in the Canyon. That is not considered feasible at this time.
What are likely disposal options?
Groundwater infiltration of high-quality treated water (currently happening with relatively low quality treated water from septic tanks and small community system effluents) and irrigation from are options available now. Snowmaking may be an additional option in the future. Highly treated wastewater is essential for using these options for disposal.
Can the service area expand after a District is formed?
Yes. Annexation can be accomplished by a petition of contiguous owners who would like to join or through a vote. The District board can accept or reject a petition or establish a vote, if needed. Forced annexation has extremely tight requirements an objective of this District formation, no is it expected to be economical or enforceable.
What are the implications the co-solution of the two Districts with treatment in the existing district on cost?
Only one treatment plant would be needed. If the 1% for Infrastructure Tax is successful, overall costs would be lower for the co-solution. If it is not successful then the difference will be smaller and not yet clear (this analysis is being conducted in March).  Regardless of Resort Tax outcomes, the Operations, Maintenance and Replacement (OM&R) costs for the co-solution will be less on a per-person basis because of the economy of scale.
What is an apples to apples comparison between scenarios? Between them and existing systems?
Full cost estimates include capital costs, operation and maintenance and any service fees assessed. The current estimates of the two centralized treatment options are not completely comparable yet, since total and OM&R cost estimates have not been converted into connection fee and rate cost estimates. To compare to existing systems, O&M and replacement costs for  septic and community systems must also be considered.
What is the current nitrogen load from septic and community systems?
It is currently approximately 4,600 pounds per year and is projected to be as much as 12,000 pounds per year if growth continues and treatment methods do not improve.
What is the tipping point for the river in terms of river health? Is that in the scope of the study?
This is outside the scope of this study. It is a difficult question to answer, but a real issue and important to keep in mind. Knowing current and projected nutrient loading is an important step. The current Bureau of Mines and Geology study in the area will also be helpful once it is complete.
Is this different from recommended water and sewer district boundaries?
The most cost-effective areas for centralized treatment are in the area between the highway 64 turnoff and the school. Residents will ultimately decide any ultimate boundaries. Phasing the growth of the District could be a very useful way to grow the District as the area grows.
What would the 1% for Infrastructure Tax proposal cover out of costs?
1% Resort Tax, if approved by voters on May 5th, would cover up to $12 million dollars for a lift station and conveyance to and from the Big Sky County Water and Sewer District.  Specifically, it would cover the lift station and the forcemain from the lift station to bring wastewater up to the Big Sky WRRF, and a gravity pipeline that would convey highly treated water back to the Canyon for reuse and/or disposal.
What are the pipe locations proposed? When does that get more exact?
The main sewer collection pipes pipe would run on the west side and parallel to US 191, but collectors along the east side of 191 will be needed in the more densely developed areas to minimize the number of crossings of 191. This configuration has been used for cost estimation purposes. Exact locations would be determined in a future detailed route study and preliminary engineering report and would ultimately grow based on District development.
How much is projected overall cost? What's still missing from that estimate?
Project costs for the Canyon WRRF and the BSCWSD Co-Solution scenarios are estimated at $29.7 million and $26.1 million, respectively. Costs for individual project components are presented below with the caveat that the forthcoming Conceptual Rate Study will provide a better ‘apples to apples’ comparison that factors in annual OM&R costs, BSCWSD treatment expansion implications, and corresponding user rate and connection fee structure.


Project Component Scenario 1

Canyon WRRF

Scenario 2

BSCWSD Co-solution

Collection $7.6 Million $7.6 Million
Treatment $15.5 Million TBD, BSCWSD Coordination
2-Way Conveyance NA $11.7 Million
Disposal $6.5 Million $6.8 Million, BSCWSD Coordination
OM&R and Rates-Fees TBD TBD
What would the 1% for Infrastructure Tax proposal cover out of costs?
1% Resort Tax, if approved by voters on May 5th, would cover up to $12 million dollars for a lift station and conveyance to and from the Big Sky County Water and Sewer District.  Specifically, it would cover the lift station and the forcemain from the lift station to bring wastewater up to the Big Sky WRRF, and a gravity pipeline that would convey highly treated water back to the Canyon for reuse and/or disposal.

In addition, the 1% for Infrastructure Tax will pay for 60% of the total project cost (or $27M, whichever is less) of the cost to upgrade and expand the Big Sky WRRF. This would also benefit the Canyon residents as it reduces the overall cost of treatment for the co-solution alternative.

What happens to the rest of the area?
Decentralized options that can provide significantly better nutrient and pathogen reduction could be used to treat wastewater from more remote clusters of development. SepticNet and Treatment Wetlands similar to Bridger Bowl’s system are promising options for these areas.
How deep is the bedrock below the shallow aquifer in the canyon?
The bedrock and aquifer depth vary across the study area. The central portion of the canyon has generally more consistent aquifer conditions with depth in   the 40 to 60-foot range.
What is the growth projection?
5%. Permitted applications have grown 3.8% in the Canyon and 7% in the Big Sky Water and Sewer District area since 2008.
How does the study align the capacity with the zoning?
• The study consultants will diligently work to project future use of the land. It will take into consideration historical uses and any applications for development. Public input will also be sought.
Is there any cap on growth in the Canyon area?
Water rights limit the total feasible growth in the Canyon. The Gallatin watershed is a closed basin and senior water rights holders are downstream. Growth in this area of the Canyon is likely capped at approximately three times the existing development.
What about deed restricted properties (affordable housing)?
• This type of development is currently a zoning issue and if a District is formed, part of their decision-making process.

• The study will include load projections based on current land-use along with growth projections based on a reasonably conservative growth projection that accounts for potential of higher density housing while also recognizing potential growth limiting factors such as available water rights. Public input is strongly encouraged.

Was climate change considered in this study?
It was not in the scope of this study.
As temperatures rise with climate change, what are likely impacts to the river?
Rising temperatures also increase the chances of algal blooms, so the river may be more sensitive to nutrient inputs in the future. Lower river levels due to drier years or earlier runoff, lead to increased water temperature and also higher nutrient concentrations.
How do additional project costs get funded beyond the 1% for Infrastructure Tax?
The Big Sky Resort Tax has a 3% tax fund that a new Canyon District could apply for when developing future infrastructure. Additionally, Water and Sewer Districts are eligible for all the state and federal funding sources that are available.
Where would a Canyon WRRF be located?
A Canyon WRRF would likely be located on an undeveloped parcel in the northern half of the Phase I boundary.
Are there any seismic considerations?
Centralized treatment must meet stringent seismic codes.
What happens to costs if more people are in a District?
The costs per person, resident or business generally go down as more people join a District. This is referred to as economy of scale and is significant in public works infrastructure.
If a Canyon District is formed, does the BSCSWD WRRF have treatment capacity to accommodate the wastewater generated in the Canyon?
Yes, once expanded and upgraded in 2022, the BSCWSD would have the capacity to treat wastewater from the Canyon District, if formed.
What are the disposal sites considered in the Canyon? What kind of disposal are we talking about?
Currently, groundwater recharge is the most likely disposal method. Several drainfields in the area could be repurposed and new ones might be built. Exact locations would be determined by a combination of good sites for recharge and landowner agreements.
What is an SFE (Single Family Equivalent), and how will its growth be considered in the study?
• An SFE is a unit of growth used by municipalities, based on wastewater generation from a single family household. The value depends on household occupants, occupancy (seasonal versus year-round), and water use by the occupants. The Study will look at SFE’s within the current developments, SFE’s with full build-out of current zoning/density, and SFE’s with potential increases in density due to potential future zoning changes. The latter would only be driven by Canyon Area District formation and subsequent rule-making by a District Board, whose members would be elected by the District residents.
What are the thoughts on spray irrigation of effluent?
• Irrigation will be evaluated as a disposal alternative for treated effluent from the Canyon Area. However, successful disposal via irrigation will require either an alternative winter disposal methodology, or winter storage. Locating a reservoir in the Canyon Area will likely be challenging.

• The study will include evaluation of a range of effluent disposal alternatives including groundwater recharge, snowmaking and surface water discharge.

Is moving to centralized treatment required?
The DEQ does not currently require centralized treatment. However, trends in nitrate loads to the aquifer in the Canyon Area coupled with additional growth in the area do point to a need to reduce loading to protect water quality in the aquifer as a source of drinking water and as a tributary to the Gallatin River.
Are there any considerations to including water supply in this project?
• For the most part, the future implications are more prevalent in the wastewater and in some cases, water rights. Water rights will be considered as a relevant parameter with respect to growth projections (i.e. maximum growth may be water supply limited). Additionally, effluent disposal options may have water right implications that will be considered. The GRTF would be interested in hearing more about resident’s concerns with water, but this study will focus on wastewater infrastructure options and solutions.

More Information

For more information about the new Gallatin Canyon County Water and Sewer District, please contact district founding member, Scott Altman.

For information about Gallatin Canyon water quality, please reach out to [email protected].

For updates on the new Big Sky County Water and Sewer District wastewater treatment plant, connect with [email protected].