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DEQ assessment finds Gallatin River impaired by algal blooms

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Bright green algae blooms are visible on the Gallatin near Deer Creek trailhead in August 2018. PHOTO BY RICH ADDICKS

By Gabrielle Gasser ASSOCIATE EDITOR

Correction: A previous version of this story stated that DEQ announced its determination on July 14. The story has been updated with the correct date, June 14.

BIG SKY — In response to a petition submitted by a coalition of five organizations, the Montana Department of Environmental Quality made a preliminary finding that the middle segment of the Gallatin River is impaired by algal blooms, or an excess of algae in the water.

On June 14, DEQ announced its determination that the Gallatin merits a Category 5 impairment designation under the federal Clean Water Act. An assessment of data collected by the Gallatin River Task Force and Upper Missouri Waterkeeper revealed that the Gallatin is affected by human-made nutrient pollution and is not fully supporting two beneficial uses—aquatic life and recreation—which led to the impairment finding. 

GRTF, Upper Missouri Waterkeeper, Montana Trout Unlimited, American Rivers and the Greater Yellowstone Coalition submitted the joint petition on March 31 asking DEQ to assess the middle segment of the Gallatin and make the determination that recurrent, nuisance algae blooms have degraded the waterway. 

“This is a science-based determination that’s going to trigger a thoughtful process for understanding where the different pollution causes [are] and what do we do as a society, as a community that cares, to reduce the sources of pollution that are causing these big algae blooms,” said Guy Alsentzer, executive director and founder of Upper Missouri Waterkeeper.

Now, DEQ is holding a public comment period on the draft assessment which opened on June 20 and closes on Aug. 22. There will be a public meeting in Big Sky on July 14 where DEQ representatives will present data from the assessment and answer questions.

After the public comment period closes, DEQ will review comments and make any necessary updates to the assessment. The impairment listing will then move to the federal level where the U.S. Environmental Protection Agency will have the final authority to approve or deny the listing. If the listing is approved, it will trigger the development of Total Maximum Daily Loads which define the amount of certain pollutants a waterbody can hold without impacts to water quality and beneficial uses.

Nuisance algae blooms, which have been affecting the Gallatin for years and worsened significantly in 2018, degrade the Gallatin’s water quality and are likely caused by large amounts of phosphorus and nitrogen in the water, according to Northern Rockies Regional Director with American Rivers Scott Bosse.

“We strongly suspect that it’s excess nutrients that are getting into the river that are causing these algae blooms,” Bosse said. “It’s those excess nutrients in combination with warming waters as a result of climate change that we think are triggering these algae blooms.”

The blooms disrupt recreation while harming fish and their food sources, Bosse said, adding that the Gallatin is historically a nutrient-poor river with some naturally occurring nitrogen and phosphorus. Those excess nutrients, he says, are coming from human sources. 

The data reviewed by DEQ do not show that nutrients exceed current thresholds, but Kristin Gardner, chief executive and science officer with GRTF, pointed out that the Gallatin is more sensitive than standards set by the state.

To address those human sources of nutrient pollution, Gardner says an important project will be providing centralized wastewater treatment to the Canyon area of Big Sky, which has traditionally used septic systems. Right now, the Gallatin Canyon Water and Sewer District is conducting engineering studies to evaluate disposal capacity. Eventually, the goal is to connect the Canyon area to the upgraded water resource recovery facility in Big Sky’s Meadow Village.

Gardner expects the task force will help develop a river restoration plan working as a local liaison between the state and the community alongside the other organizations that signed the petition.

“That’s the end result of collaboration,” Gardner said, “[a bigger] impact and better results because everyone’s engaged and participating in the process.” 

As public comment begins flowing in, Bosse, Gardner and Alsentzer all agree that DEQ must focus on the nutrient pollution that causes the algae blooms. The impairment finding in its current, preliminary state lists the river as impaired based on excessive algae growth, not nutrient pollution.

Alsentzer said he’s encouraging commenters to ask DEQ to clearly state that nutrient pollution is the issue to better guide the development of TMDLs and future restoration projects.

“Let’s focus on the things over which we have control and not try to kick the can down the road with some sort of ambiguous listing for just algae pollution,” he said. “It’s not just about algae, it’s about the fact [that] manmade sources of nutrients are giving rise to the causal effect of severe algal blooms that are affecting recreation and aquatic life.”

The impairment listing by DEQ is a positive step in the right direction, Alsentzer said, adding that his organization will continue collaborating with other organizations to make appropriate decisions.

“If there was ever a community that cares about the river and depends on the river, but also has the means to properly and sustainably protect the river, it’s the community of Big Sky,” he said.

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