Update: Big Sky’s Big Water Problems

As we enter spring 2024 runoff on the Gallatin River, let’s recap what’s happening in Big Sky, what steps have been taken to restore the health of the middle Gallatin, where there are still gaps in protecting water quality, and what solutions exist to ensure a sustainable water future for the community of Big Sky and the river.

When we talk about Big Sky’s water woes, let’s first celebrate a key success – and milestones for river protection – of 2023: a middle segment Gallatin River impairment determination. After Waterkeeper completed five years of pollution patrols and investigations of the Gallatin River’s recurrent neon-green algal blooms, including first-of-its-kind drone surveys, we secured a landmark impairment determination for the middle segment of the Gallatin in May 2023. 

What is an impairment determination and what role does it play in cleaning up the Gallatin? Under the federal Clean Water Act, states are required to monitor waterways and keep a “303(d) list” of waterways that are failing to meet their designated uses (fish, swim, drink, etc), and as such, are impaired. Every two years, those lists are submitted to EPA for approval. Once a waterway is deemed “impaired” under section 303(d) of the Clean Water Act, the state must identify the pollutant causing the impairment and develop a TMDL (Total Maximum Daily Load), or pollution diet, to reduce the pollutant(s) causing or contributing to the impairment. For more background on impairment designations and TMDLs, click here. Remember, TMDLs represent both an enforceable pollution control planning tool for many human sources of pollution, and a determination that allows access to significant restoration funding sources. 

It’s worth noting that the petition for Gallatin River impairment identified nitrogen and phosphorus as key pollutants causing degradation, yet Montana Dept. of Environmental Quality (DEQ) submitted the impairment listing to the EPA for “algal blooms” rather than the nutrients that give life to algal blooms, likely because water quality monitoring of nutrient concentrations in the Gallatin over the past several years did not indicate consistent exceedances of numeric nutrient water quality standards for nitrogen and phosphorus. However, previous river sampling only occurred during the day, when plants photosynthesize and take up nutrients, and during the growing season, potentially affecting the accuracy of representative nutrient sampling. A leading hypothesis is that nighttime sampling and sampling outside of the growing season would likely reveal increased nutrient pollution in the river, which DEQ plans to do during the 2024 sampling season. Regardless, EPA formally approved the middle segment Gallatin listing for ‘nuisance algal blooms,’ albeit with explicit reference that nuisance algal blooms do not occur without excessive nutrient loading and expectation that forthcoming pollution reduction planning would emphasize nutrient sources. Thus, the forthcoming Gallatin TMDL needs to focus on identifying and reducing nutrient pollution inputs.

So, what are the main inputs of nutrients to the river? Nutrient pollution can arise from certain agricultural practices, development, wastewater and industrial effluent, or urban and stormwater runoff. Nutrients from erosion, and specifically the volcanic sediments of the Greater Yellowstone Ecosystem, are also natural sources. Recent analyses of Big Sky nutrient sources demonstrate that inadequately treated wastewater, antiquated septic systems, and stormwater from impervious surfaces are a part of the human-based nutrient pollution problem. 

As a first step in the right direction for a major human source of nutrient pollution, the Big Sky County Water & Sewer District’s Wastewater Resource Recovery Facility, a new membrane bioreactor (MBR) is being built in Big Sky’s meadow area and is scheduled to be fully operational by October 2024. The community has invested into this new facility that offers significantly better treatment than the current facility; it will also increase daily treatment capacity from 600,000 gallons per day to 910,000 gpd. It’s important to note, however, that the levels of treatment offered by the MBR facility are still far above the legal limits needed to protect surface water quality. 

Another issue that has received next to no attention so far is that of stormwater. Which is to say, there is no existing understanding of how widespread land-use transformation in Big Sky has altered the landscape’s topography, and specifically transformed natural meadows, forests, and grassland, into a variety of impervious surfaces, from road networks, to parking lots, to roof-tops, to impacted golf courses. Impervious surfaces related to commercial, industrial, institutional and residential land uses have been shown in other jurisdictions to be a significant part of the problem with nutrient loading to local waterways. Indeed, the DEQ’s recent April public meeting on big picture results from its summer 2023 Gallatin River monitoring showed statistically significant increases in nutrient loading after precipitation events. This data is usually the hallmark of stormwater contributions, and is clear evidence that there needs to be a quantification and qualification of how various land use sectors are contributing to surface water pollution. Don’t forget that the West Fork Gallatin and most of its tributaries have been listed as impaired due to nutrient and sediment pollution for over a decade, and sadly no progress has been made in solving these problems. Key solutions for the West Fork watershed, and potentially the Gallatin River, may well come in part from holistic, and mandatory, best management practices in new and redevelopment, including but not limited to Low Impact Development code and Green Infrastructure requirements, both of which are not only cost effective, but when implemented across sectors, are proven means to mitigate and control stormwater loading to surface water.

Another wrinkle in the river protection problem is in Big Sky’s Canyon Area. This area of Big Sky is comprised of disconnected commercial, residential, and industrial land uses all reliant on septic systems both large and small. As part of the agreement to partially fund the new MBR treatment facility, the Big Sky Resort Area Tax Board required the BSCWSD to work with the Canyon Sewer District in securing a bi-directional wastewater pipeline to and from the Canyon. The basic proposal is hooking up the biggest sources of pollution in the Canyon and piping sewage to the new MBR facility to be treated, and then piping that treated sewage back down to the Canyon for disposal via groundwater infiltration or irrigation reuse. A key nuance is the condition that the Canyon Area will receive far more wastewater for disposal than it sends up for treatment; this is based on the perception that wastewater disposal in the Canyon’s groundwater is both legally and practically easier than disposing of wastewater in the upper resort area, or directly to the mainstem Gallatin River.

Given that everyone supports river protection and solving the thorny issue of poor treatment offered by septic systems in Big Sky, the root issue becomes “what level of wastewater treatment is needed to protect local water quality?” Presently the larger engineering community thinks that groundwater disposal in the Canyon is a silver bullet to longstanding wastewater treatment and disposal for Big Sky, apparently because the wastewater nutrient concentrations from the new MBR facility will likely meet Level A-1 concentrations, an antiquated treatment standard written into Montana’s pollution control rules. Notably, there is no science demonstrating that injecting hundreds of thousands of gallons of A-1 wastewater each day into the Canyon’s groundwater will assure protection of the Gallatin River, or solve the existing problem of recurrent nuisance algal blooms. Rather, there’s a perception that removing existing septic system contributions and playing a game of math about how much more, better-treated, wastewater can then be disposed of, equals sufficient water protection strategies. Sounds a lot more like profit-margin-driven development and “trust us” rhetoric than proven river protection strategies.

A key piece of the puzzle that none of the existing wastewater “solutions” contemplates is the Gallatin River’s impairment determination. First, remember that existing science demonstrates the vast majority of shallow Canyon groundwater receiving wastewater heads pretty quickly to discharge into the Gallatin River, usually in 3-5 weeks. Most stakeholders, Waterkeeper included, are awaiting the results of the Montana Bureau of Mines and Geology GWIP study into groundwater in Big Sky’s Canyon Area and modeling of subsurface nutrient fate and transport, a study that can help pinpoint the validity – or not – of proposed wastewater disposal strategies. Second, the Canyon soils through which groundwater tracks includes cobbles and like larger grained sediments, which both allow relatively quick groundwater movement but also possess limited natural treatment based on their composition and the relatively high concentrations of subsurface oxygen (i.e., natural denitrification subsurface requires anoxic conditions among other factors). 

These scientific considerations are important because under state law the legal imperative of any pollution discharge is first, will that discharge alone or in combination with other pollution harm beneficial uses of surface water? If it will, the discharge cannot be authorized without first undergoing a stringent Nondegradation Policy Analysis, something DEQ has only performed a handful of times in the state’s history, and which could result in the discharge not being allowed. Similarly, federal law can encompass groundwater discharges that are the functional equivalent of putting a pipe in the river; in the case of the mega-disposal plan from the resort community, there is a very real question about whether future wastewater disposal in Big Sky must meet federal CWA rules and requirements for new pollution discharges.

This inquiry also brings us full circle to the question of what import, if any, does the designation of the Gallatin River as impaired bring? Put simply, if we can agree that science demonstrates a strong likelihood that any new discharge of wastewater in the Canyon Area falls within the scope of the federal CWA’s NPDES permitting program, then the law is clear that no new wastewater pollution discharges are allowed until the Gallatin River has an EPA-approved TMDL (aka, pollution diet) placed on the books, and even then only if there is reasonable assurance that planned restoration strategies are capable of creating new assimilative capacity in the river to handle new pollution inputs. In terms of a timeline, DEQ has estimated it will take 4-6 years to develop a Gallatin TMDL, and the first season of water quality monitoring just took place in summer 2023.

In sum, it’s clear that the assimilative capacity of the Gallatin River for more pollution loads is nonexistent, and further new pollution sources to the river are inappropriate, yet the state continues to unlawfully rubber stamp brand new development. Waterkeeper is currently litigating Phase I of the Quarry Project, a new major subdivision without considering the cumulative impacts and degradation potential of the new development that has the exact same fallacies that the 18th Judicial District ruled unlawful in Lazy J South case. Despite the pending lawsuit, Gallatin County just signed off on Phase 2 of the Quarry Project in December 2023. A coalition of NGOs and over 50 citizens requested that DEQ make transparent a public process on its consideration of Phase 2 of the Quarry, but as of today, DEQ has yet to respond.

Big Sky no doubt has some big water problems to solve, and a lot of work needs to be done to restore the health of the Gallatin River. Fortunately, Big Sky has the ability to become a model for mountain resort communities. There is proven, existing technology, beyond a MBR, that can treat wastewater to appropriate levels to protect the Gallatin’s water quality. Big Sky can turn its liability into an asset by investing in next level treatment to reduce the existing pollution issues, restore degraded waterways, and ultimately solve both water supply and water pollution constraints. 

Until a science-based TMDL clean up plan is in place, Waterkeeper will continue to birddog any new pollution inputs to the river as those are blatantly inappropriate both legally and scientifically. With the quantity of wastewater entering the Gallatin from the West Fork, the MBR, and the Canyon area, the assimilative capacity of these waterways remains nonexistent, and any new development is likely to exacerbate existing problems. DEQ should be leading this process and working alongside the community of Big Sky and stakeholders to holistically consider and solve the problem of growth outstripping a river’s carrying capacity by conducting a full Montana Environmental Policy Act Environmental Impact Study (EIS) to consider these issues as a whole. Sadly, we see little such leadership from our state’s pollution control agency.

In terms of local stakeholder commitments to a better water management paradigm, let’s remember that the Big Sky Sustainable Water Solutions Forum, including Big Sky Resort, Lone Mountain Land Company, and the Big Sky Sewer and Water District, explicitly agreed that wastewater management should “ensure wastewater does not have a negative impact on the ecological health of the river systems and groundwater resources.” Now is the opportunity to make good on that promise, invest in high levels of treatment, and pay it forward. Let’s face it, if there’s anywhere that can, and should, invest in protecting its water resources, and taking responsibility for human impacts on our outdoors heritage, it’s the community of Big Sky.