A new federal lawsuit is challenging EPA’s approval of Montana’s shift away from numeric nutrient pollution standards—rules that had guided permitting benchmarks since 2014.
Jump to:
- What the lawsuit is about
- Numeric standards out, narrative standards in
- How House Bill 664 drove the shift
- DEQ’s case: predictability and science
- What the plaintiffs allege
- What this means for Montana
- FAQ
- Who sued: Flathead Lakers, Upper Missouri Waterkeeper and the Confederated Salish and Kootenai Tribes (CSKT).
- What’s being challenged: Federal approval of less stringent nutrient pollution standards in Montana.
- What changed: Numeric nutrient standards were eliminated and replaced with narrative, site-specific criteria.
- Where it’s filed: U.S. District Court in Great Falls.
What the lawsuit is about
Flathead Lakers, Upper Missouri Waterkeeper and CSKT sued the U.S. Environmental Protection Agency (EPA) over Montana nutrient pollution standards. The lawsuit challenges federal approval of less stringent water quality standards for nutrient pollution in Montana.
The complaint centers on EPA’s decision in October 2025 to approve Montana’s new regulatory framework for nutrient pollutants, including nitrogen and phosphorus.
Numeric standards out, narrative standards in
EPA’s decision eliminated numeric nutrient standards that had defined permitting benchmarks in Montana since 2014. EPA replaced numeric nutrient standards with narrative nutrient standards based on subjective, site-specific criteria.
Water quality advocates described the narrative standards as “arbitrary” and “reactive.”
How House Bill 664 drove the shift
The policy shift was prompted by the Montana Legislature’s passage of House Bill 664, which repealed numeric nutrient standards. House Bill 664 directed the Department of Environmental Quality (DEQ) to delete all references to numeric nutrient standards.
In October 2025, EPA approved the revised terms laid out by HB 664 as “consistent with the Clean Water Act.”
DEQ’s case: predictability and science
DEQ said the new law provides greater regulatory predictability for permittees while still ensuring the agency applies “the best science available.”
DEQ Director Sonja Nowakowski testified on Feb. 26, 2025 about the numeric nutrient standards and a statewide nutrient variance rule. Nowakowski said the 2014 adoption included a statewide nutrient variance rule allowing dischargers to achieve permit limits over a 20-year period.
Nowakowski said Upper Missouri Waterkeeper successfully targeted that variance in a lawsuit, rendering the numeric nutrient standards “technologically infeasible.”
What the plaintiffs allege
Plaintiffs allege the policy shift gives would-be polluters too much leeway by rolling back protective criteria in place for over a decade.
- Clean Water Act: The lawsuit alleges EPA violated the Clean Water Act by approving Montana’s new standard “without scientific basis.”
- Endangered Species Act: The lawsuit alleges EPA violated the Endangered Species Act by failing to adequately consult with the U.S. Fish and Wildlife Service.
Upper Missouri Waterkeeper distributed a press release on Jan. 28 when the groups announced the lawsuit.
What this means for Montana
At the center of the dispute is how nutrient pollution permits are benchmarked in Montana: numeric standards that had been used since 2014 versus narrative nutrient standards that rely on subjective, site-specific criteria. With EPA approving the HB 664 framework in October 2025 as “consistent with the Clean Water Act,” the lawsuit asks a federal court to weigh allegations that the approval was “without scientific basis” and that required Endangered Species Act consultation was inadequate.
The complaint was filed in U.S. District Court in Great Falls.
FAQ
Who filed the lawsuit?
Flathead Lakers, Upper Missouri Waterkeeper and the Confederated Salish and Kootenai Tribes sued the EPA.
What did EPA approve?
EPA approved Montana’s new regulatory framework for nutrient pollutants, including nitrogen and phosphorus, in October 2025.
What changed in Montana’s standards?
EPA’s decision eliminated numeric nutrient standards used as permitting benchmarks since 2014 and replaced them with narrative nutrient standards based on subjective, site-specific criteria.
Where was the complaint filed?
In U.S. District Court in Great Falls.
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