Federal Approval of Montana’s Numeric Nutrient Standards Repeal Threatens Clean Water Protections Nationwide
Upper Missouri Waterkeeper is raising the alarm that the Trump Administration’s Environmental Protection Agency (EPA) could set a dangerous, polluter-friendly precedent by approving the State of Montana’s illegal rollback of science-based water quality standards. As featured in the Mad About Montana podcast, Waterkeeper and partners recently filed a lawsuit against the EPA for approving the State of Montana’s illegal repeal of numeric nutrient water quality standards and replacing them with arbitrary, reactive narrative standards that lack measurable goalposts for water quality protection.
“Over a decade ago Montana led the nation in water protection by adopting numeric nutrient water quality standards grounded in science. EPA’s acquiescence to polluting interests and the State of Montana’s rollback could have precedent setting implications about whether science – or politics – will guide water quality protections across the country,” said Guy Alsentzer, Executive Director of Upper Missouri Waterkeeper. “EPA’s rubber-stamping of Montana’s illegal rollback of numeric nutrient water quality standards is simply unprecedented under the federal Clean Water Act. It also serves as a national signal to polluters and special interests that this EPA administration will favorably consider nearly any state proposal seeking to weaken science-based water quality protections.”
In 2014, Montana became one of the first states to adopt numeric nutrient standards to control nitrogen and phosphorus pollution after its scientists drafted protective criteria based on over a decade of study (approved by EPA in 2015). EPA had encouraged states to adopt numeric nutrient criteria for over two decades, including through several federal register notices, guidance, and funding incentives. Montana’s numeric nutrient criteria were based on best-available science developed on site-specific, watershed scales; the numeric criteria reflected the sensitive nature of Montana’s headwaters to nutrient pollution, and set thresholds designed to affirmatively protect Montana’s water resources before harmful biological responses occur.
Part of the rationale for the 2025 Montana Legislature’s repeal of numeric nutrient criteria was the unfounded allegation that, absent a mandatory “general nutrient variance” for all regulated sectors, implementing numeric nutrient criteria in Montana became impossible. The concept of a “general nutrient variance” first arose alongside the State’s 2014 numeric nutrient standards rule package. There, Montana adopted a 20-year “variance” rule that exempted all nutrient wastewater dischargers from attaining pollution limits. This essentially gave a free pass to most polluters from complying with the protective permit limits established by numeric nutrient standards. Waterkeeper successfully sued EPA over its blanket approval of general nutrient variances on the basis that polluters need to be incrementally working toward compliance, and the blanket variance with no end-date for compliance was ruled unlawful by the District Court of Montana. Later, on appeal to the 9th Circuit Court of Appeals, that court determined EPA could lawfully approve a variance for municipalities who provided evidence that complying with nutrient criteria would lead to ‘substantial and widespread economic harm.’
Thus, while 36 Montana municipalities were thereafter allowed nutrient variances under the 9th Circuit’s order, all other polluters and industrial sectors were denied the ability to automatically be exempted from compliance with numeric nutrient criteria.
While the general variance was thrown out by the courts, the variance process itself was never eliminated. Individual variances, phased compliance schedules, and reasonable timelines always remained available for any permittee that could lawfully justify them by demonstrating widespread and substantial economic harm.
Unsatisfied with the loss of automatic exemptions from numeric nutrient criteria, special interest groups successfully lobbied the 2021 Montana Legislature to pass Senate Bill 358, a bill that sought to eliminate numeric nutrient criteria and force the State to adopt rules implementing “narrative nutrient criteria” for all waterway protection and restoration efforts. When the State refused to submit SB358 to EPA for review and approval – a mandatory requirement of federal law – Waterkeeper again sued EPA to take action. And, in response to Waterkeeper’ litigation, in May 2022, EPA did take action and disapproved SB358 for all Clean Water Act purposes in Montana. This action was based upon the unscientific character of the legislation, mandates contrary to CWA requirements, and the unprotective record of the State of Montana in applying narrative criteria to regulate the very real challenge of nutrient pollution across the state.
After EPA’s May 2022 disapproval action one would think the matter settled. However, instead of implementing numeric nutrient criteria as required by law and directed by EPA, instead the Montana Dept. of Environmental Quality administratively continued pollution permits (i.e., sat on pending pollution permits with nutrient limits instead of renewing those permits with limits based on numeric nutrient criteria) and refused to make biannual river assessment and pollution impairment determinations based on numeric nutrient criteria.
When the 2025 Montana Legislature met, it quickly passed House Bill 664, which specifically and solely eliminated numeric nutrient criteria for all purposes across the State. Notably, there was no directive to establish equally protective criteria for nutrient pollution control, nor any other scientific evidence demonstrating how numeric nutrient criteria were no longer adequate to protect local waterways from nutrient pollution. HB664’s repeal of numeric nutrient criteria was, quite simply, an abrupt departure from science-based water pollution control in Montana.
In reviewing the 2025 Legislative testimony on HB664 it becomes clear that Montana’s repeal of numeric nutrient standards was largely driven by cost concerns by large dischargers, including municipalities, oil, gas, mining, and wastewater utilities. While upgrades to advanced pollution control technology capable of meeting nutrient standards can be costly, no law requires immediate, overnight compliance. Rather than seek individual variances and phased implementation strategies, items that are well-known implementation tactics, big polluters influenced state leaders to eliminate the standards themselves.
EPA summarily approved the elimination of Montana’s numeric nutrient standards on October 3, 2025, absent any scientific basis and without even examining how the elimination of scientific standards for one of Montana’s most-common types of water pollution could harm endangered and threatened species across the State. EPA’s rollback approval is setting a dangerous precedent for the rest of the country by directly undermining baseline requirements of the Clean Water Act (that our water quality standards be based on best available science demonstrated capable of protecting water quality and designated uses of water), and thereby opening the door for other states to abandon science-based protections in favor of politically motivated, polluter-friendly decisions.
Waterkeeper’s January 2026 lawsuit seeks to overturn EPA’s approval of Montana’s water quality standards rollback and reinstate numeric nutrient standards that will protect the state’s waterways, fishery health, drinking water, and communities.