Gutting Water Protections by Repealing Numeric Nutrient Standards Contrary to Science and Federal Law
Last week, the Environmental Protection Agency (EPA) sent a letter to the Montana Department of Environmental Quality (DEQ) approving the state’s repeal of scientific numeric nutrient water quality standards for arbitrary, reactive narrative standards pursuant House Bill 664 passed in the 2025 Legislative Session.
Numeric nutrient criteria are essential, best-available science designed at protecting Montana’s waterways from the most pervasive pollutant causing river degradation in the state – nutrients. Rolling back numeric nutrient standards, the proverbial measuring stick for nutrient pollution, will weaken protections against pollution, including noxious algae causing nitrogen and phosphorus pollution, in rivers and lakes across the state. Read more on why narrative standards are ineffective mechanisms for controlling and stopping pollution here.
“This is another gift to polluters and developers at the public’s and environment’s expense. There is no scientific or legal basis for abandoning numeric nutrient standards that prevent nutrient pollution in our rivers and streams. The State of Montana and Governor Gianforte are throwing away the measuring stick used to determine when water quality is being degraded and what’s necessary to protect clean water, which further undermines polluter accountability and enforcement,” said Guy Alsentzer, Executive Director of Upper Missouri Waterkeeper. “The EPA, under this administration, is clearly picking winners and losers based on politics rather than science. By approving Montana’s rollback, the EPA is siding with polluters at the expense of Montanans’ clean water, public health, and outdoor heritage.”
For over a decade, Montana’s numeric nutrient water quality standards have provided clear, measurable benchmarks for limiting nutrient pollution in the state’s waterways. As one of the first states in the country to adopt numeric nutrient standards in 2014, based on decades of science demonstrating clear links between nutrient pollution and algal blooms, degraded fisheries, and unsafe drinking water, Montana was leading the charge in protecting our vulnerable clean water resources and had the most protective water quality standards on the books.
Repealing numeric standards and reverting to narrative standards is a giant step backwards that fails to hold polluters accountable and puts Montana’s finite water resources at increased risk of pollution, which in turn threatens fish and wildlife, world-class recreational opportunities, and Montana’s $1.3 billion fishing economy.
Since 2021, when the state took similar actions to repeal numeric nutrient criteria but were struck down by the EPA after Waterkeeper’s advocacy, Montana DEQ has unlawfully stalled implementation of the Clean Water Act’s nutrient standards, ignoring EPA’s directive to enforce the law. Now, with federal approval, the state is issuing discharge permits without the numeric limits necessary to prevent harm, externalizing pollution costs onto the environment, wildlife, communities, and everyone else’s pocketbooks.
It’s also worth noting that the state’s so-called replacement narrative standard is a vague and unenforceable provision found in Administrative Rule 17.30.637 – a policy that has never been meaningfully implemented or enforced. In fact, in adopting numeric nutrient criteria over a decade ago, EPA found Montana’s narrative nutrient standard inadequate to protect or restore water quality. These former scientific findings are now being ignored and abandoned. Instead of working on implementation and bringing polluting sectors into compliance, DEQ and EPA are focused on taking two-steps backwards and removing scientific thresholds for pollution control.
Waterkeeper is reviewing EPA’s decision and is prepared to take necessary actions to defend Montana’s vital clean water resources against unscientific decision-making that’s both contrary to federal law and will risk the future health of our valued waterways.