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Every Drop Counts: Impairment listing and TMDL, what does it all mean for the Gallatin River?

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The recent proposed listing of the middle segment of the Gallatin River as impaired has gained a lot of well-deserved attention in headlines lately. It calls to question many things, not the least of which is ‘what does that even mean?’ and ‘is the Gallatin River in peril?’ The short answer is that this is not all bad news. The longer answer is that it is the first step in a solution that will take a few years to make an impact, but is the best solution for the Gallatin’s long-term health.

After repeated summers with severe, widespread algal blooms on the mainstem Gallatin caused by sufficient nutrients and climate conditions perfect for nuisance algae growth, it is the right time for a proven, scientific, and legal process to solve the problem. This impairment listing will put that plan in motion.

The request to determine the Gallatin as impaired came from a petition submitted by a collection of conservation and environmental groups—including the Gallatin River Task Force, Upper Missouri River Waterkeeper, Montana Trout Unlimited, American Rivers, and Greater Yellowstone Coalition. With recurring algae blooms and unanswered questions about the causes of these blooms, the petition—and the listing—was the best way to put science to work at finding the most effective solutions.

But let’s cover the basics first. When determining if a river should be listed as impaired, many factors and extensive available data need to be considered for review. In a monitoring contract with the Gallatin River Task Force over the last four years, the DEQ was able to collect and utilize the necessary data—including photos, algae measurements, and other levels of “macroinvertebrate benchmarks”—to make the determination for the listing as impaired. 

The Montana DEQ’s proposal lists the Gallatin as impaired for excessive algal growth, even though nutrient levels in the Gallatin are less than the state standards for those nutrients. The good news is, while sounding detrimental, the impairment listing requires the development of a total maximum daily load (TMDL) and a plan that will provide a roadmap to improved water quality on the Gallatin for future generations. A TMDL is the river’s threshold for a controllable pollutant before it impacts water quality; in this case nuisance algae growth, and other factors that affect algae growth. In other words, what is the threshold of the Gallatin to remain healthy at the influx of ongoing conditions and excessive nutrients that are creating the perfect storm for recurrent widespread algal blooms.

Over the next few years, the DEQ will put significant resources into monitoring these pollutants, not only to understand what the Gallatin’s thresholds are, but also to identify sources of pollution to the river. From there, the community, and most notably the Task Force, has the information necessary to create a collaborative Watershed Restoration Plan that will reduce algae blooms in the Gallatin. While changes and progress won’t be seen overnight, or even by the summer’s end or next year, the hope is that the long-game solution ahead will put the Gallatin back on a trajectory for fewer algae blooms.

While the DEQ’s development of a TMDL is an important next step, there are methods and practices we can implement while this is taking place that will contribute to lowering the availability of excessive nutrients in the river currently contributing to favorable conditions for late summer algae blooms. Limiting fertilizers, maintaining septic systems, supporting regenerative restoration projects throughout the watershed, and other tactics will all have a cumulative and positive impact on the health of the Gallatin River.

If the proposal to list the Gallatin as impaired is approved by the Environmental Protection Agency, the section of the river from the Yellowstone National Park boundary to the confluence with Spanish Creek (the middle segment) has promising potential to return to the healthy algae levels that we all want to see. Listing the waterway as “impaired” is a critical step to address the known pollution problems, restore the Gallatin, and ensure the sustainability of both the resource and our community. We all win with a clean Gallatin River.

Marne Hayes is the communications manager for the Gallatin River Task Force.

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