In 2023, Montana Department of Environmental Quality approved a subdivision in the Gallatin River Valley. That included eight new septic systems. These systems can cause pollution in nearby rivers and degrade water quality.
Environmental group Upper Missouri Waterkeeper sued. It argued the state failed to assess cumulative impacts from the septic systems and how they may harm the river.
"This is about the idea that we have to view river systems as what they are — which is an interconnected tapestry — and how we, as humans, are putting pollution into it matters," Executive Director Guy Alsentzer said.
Gallatin County District Court Judge Andy Breuner agreed.
DEQ has already listed the Gallatin river as “impaired,” and is still working to figure out why. Breuner wrote that approving a "substantial project” next to the Gallatin river is irrational, knowing the river is unhealthy without knowing why. DEQ now needs to address the court’s concerns for the project to continue.
This summer DEQ approved the second phase of the same subdivision. Upper Missouri River Waterkeepers sued over the decision, citing similar concerns, and challenging a new state law that exempts certain septic systems from environmental review.
DEQ declined to comment on the ongoing litigation.
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In 2023, the DEQ listed sections of the Gallatin River as impaired due to recurring algal blooms. The blooms choke out fish and degrade water quality. State scientists are amid a six-year study trying to understand what's causing the harmful blooms. The state says it will use the results to inform local development regulations and a plan to protect the river. -
Montana environmental officials are proposing to give part of the Gallatin River a pollution designation as they research the factors for excessive algae growth.
