Taking steps forward: State moves to protect Gallatin River as construction on Big Sky’s new wastewater plant picks up | Environment

The upgraded and expanded Big Sky Water Resource Recovery Facility will have a grain silo style, and once the plant is up and running, it will be capable of treating about 910,000 gallons of municipal wastewater per day — a 50% increase in capacity from the town’s current plant.

The new facility can handle a lot more sewage, better accommodating the rapid pace of development in the Big Sky area. But it can also treat that effluent to a much higher quality, which should open up more opportunities for reuse.

Kristin Gardner, executive director of the Gallatin River Task Force, said people are withdrawing more from the groundwater as more homes are built, and a warming climate is causing snow to melt earlier and streamflows to dwindle later in the summer.

“We’re seeing significant pressure on our water supply,” she said. “Groundwater recharge and snowmaking are options I could see would be beneficial, if done in a strategic manner. This updated plant will allow for that.”

“We’ll take this plant about as far as any plant can go in terms of removal of those nutrients, because they are what set off algal blooms in our watersheds,” said Scott Buecker, wastewater practice leader for the consulting firm AE2S Engineering.

Construction on the new plant is gaining momentum, but the Gallatin River is also inching toward an inflection point. This August, nuisance algae cropped up along the riverbed for a fifth consecutive year, and officials are beginning to notice slight shifts in aquatic life.

The results from a recent bout of aquatic insect monitoring indicate that the river is supporting more bug species that do better in eutrophic conditions, which are driven by an overabundance of nutrients. However, officials are quick to point out that the shift could be the consequence of multiple stressors, like warmer or more turbid water.

This summer, “we saw more algae not only downstream of Big Sky, but also upstream of Big Sky in the Taylor Fork, and actually in Yellowstone National Park,” Gardner said. “It’s a widespread issue… When you start seeing impacts to aquatic life, it really defines it as an urgent issue, in my mind.”

Guy Alsentzer, executive director of the group Upper Missouri Waterkeeper, said the fact that changes are being observed among macroinvertebrates is a significant cause for concern, and it demands action.

“We need to get a grasp on what’s going on, and we shouldn’t be looking the other way when there’s a slew of new building projects,” he said. “There isn’t one smoking gun. It’s the totality of how we’re changing the landscape and cumulatively decreasing the water quality of the Gallatin River.”

Beyond the border of Yellowstone National Park, the Gallatin River is a hub for fly-fishing, whitewater rafting and overall recreation. Non-toxic filamentous algae started to appear along the riverbed in 2018, and it has reappeared every summer since.

Nutrients are found in all rivers, and they are essential for the growth of plants. But when nitrogen and phosphorus accumulate at unnatural levels, they prime waterways for algal growth. Sunlight, water clarity, heightened water temperatures and low stream flows are the triggers.

Widespread algal blooms have an immediate effect on a river’s aesthetics and recreation, and over time, aquatic life can change. The number of insects out on a river system can increase, but those bugs tend to be smaller in size.

Larger stonefly hatches can drop off, and tiny mayfly hatches can become more abundant, said Darrin Kron, Water Quality Monitoring and Assessment Section supervisor for the Montana Department of Environmental Quality. In the Gallatin River, DEQ is already noticing slight changes.

As bug numbers increase overall, fish grow bigger, but only up to a certain point. “There’s a tipping point where you may have dissolved oxygen problems in areas where you’re trying to rear fish fry,” Kron said. “At that point, it could affect the overall fishery, but we’re not there yet.”

Upper Missouri Waterkeeper, the Gallatin River Task Force, Montana Trout Unlimited, the Greater Yellowstone Coalition and American Rivers filed the petition in response to DEQ’s decision to forgo publishing a biennial “Integrated Report,” which lists the waterways that don’t meet state water quality standards.

Three months later, DEQ acquiesced. It preliminarily classified the Gallatin River between the border of Yellowstone National Park and the confluence of Spanish Creek as water quality impaired, launching the lengthy process for controlling pollutants.

A scoping period ran for 60 days, and now the department is reviewing and addressing the more than 2,500 public comments it received, all of which were supportive of an impairment designation, according to Kron.

The U.S. Environmental Protection Agency must accept or deny DEQ’s decision before the planning process can move ahead. Then the state agency can get started on developing a “total maximum daily load” planning tool, which is used to set limits on pollutants.

Because multiple factors could be contributing to the algal growth, the department has to keep all options on the table, said Andy Ulven, DEQ Watershed Management Section supervisor. It plans to collect more data and conduct an interim study, which could take two to three years.

After that, officials will work to produce the TMDL planning tool, which Ulven described as a pollution diet for the river. That could also take two to three years.

DEQ needs to identify the pollutant levels that the water body can sustain before it no longer meets water quality standards, and then it can allocate pollution caps to the various sources.

The department may also work with local groups to conduct restoration projects in the watershed. Ulven said an impairment designation opens up more opportunities for the groups to access funding.

Alsentzer said DEQ’s determination should be finalized as soon as possible, and the department needs to recognize “the well-established science showing that algal blooms do not occur but for nutrient loading.”

“Without human impact, you do not have algal blooms,” he said.

Gardner said it does appear that the Gallatin River is more sensitive to nutrient pollution than other rivers and streams, and even though the TMDL planning process might take years, the task force and others are already working on solutions.

Big Sky is home to the task force’s trout-friendly landscaping program, and the organization is also working to address nutrient pollution in tributaries. But the wastewater treatment plant upgrade is among the most significant steps forward.

The project was no small investment. In 2020, voters in the Big Sky Resort Tax District approved a 1% increase in the unincorporated town’s sales tax to fund the now $60 million upgrade and expansion.

Instead of piping treated wastewater directly into the Gallatin River, the Big Sky County Water and Sewer District and other local entities store it in holding ponds during the winter, then irrigate area golf courses with it in the summer.

As the Big Sky area develops, it’s becoming more difficult for the district to find space to store effluent through the winter. It’s looking for more ways to reuse wastewater, and improving the quality of treatment is key to that goal.

“Nobody likes building these huge storage ponds, and getting land to do that is becoming more difficult,” said Ron Edwards, the district’s general manager. “Getting into winter and year round disposal options is a big part of the future of what we need to be doing.”

Many conservation groups are concerned that the lack of storage capacity is leading to the over-irrigation of area golf courses, and they fear that’s causing excess nitrogen and phosphorus to leach into the groundwater and area streams.

The task force and other organizations support the snowmaking idea, in part because of its potential to reduce nutrient pollution and bolster snowpack, adding to the overall water supply. Others oppose it, fearing it could have unintended consequences, like adding pharmaceutical pollution to the river system.

What’s clear is that the new plant will treat the effluent that’s used for snowmaking and other purposes to a much higher standard, and it will help get the district “into a 12-months-a-year disposal scenario,” according to Edwards.

There’s another piece of the puzzle, which is that eventually, the district would like to construct pipelines down to the corner of Big Sky and pump up wastewater from homes in the canyon area for centralized treatment, Edwards said.

The canyon is where there are lots of old septic systems, which may be adding to the nutrient pollution problem. The size of the new plant is designed to accommodate the current district, but it is being built in a way that allows for further additions.

Gardner said it’s important to connect as many septic systems to centralized treatment as possible and to continue taking steps to protect the river, even when a total maximum daily load plan isn’t there to establish rules pertaining to pollution.

“I feel like people moved here because they really appreciate the natural resources and the Gallatin River,” she said. “We’ve had a lot of encouraging conversations and proactive decisions to move forward with management actions that might be more expensive, but will actually protect the river.”

Alsentzer said that growth isn’t necessarily the enemy. Pollution is the enemy, and while humans and businesses aren’t bad, not taking responsibility for growth is. The treatment plant upgrade is a critical step, but that doesn’t mean the community can do whatever it wants with wastewater, he said.

“I applaud progress where it’s being made, but I want to make sure we’re all sitting down at the table and looking at the facts,” Alsentzer said. “Let’s let the science decide — not expediency and development pressure.”