1. What happened to Montana’s numeric nutrient criteria?
In Spring 2025, the Montana Legislature passed and Governor Gianforte signed HB 664, a piece of legislation that rolls back numeric nutrient water quality standards for all water pollution control and water restoration purposes across the State.
Under the federal Clean Water Act, the EPA must approve or deny any revision of water quality standards. Unfortunately, under the current federal administration, on Oct. 3, 2025 the EPA approved the State of Montana’s elimination of numeric nutrient criteria, contrary to their previous actions in 2015 approving numeric nutrient criteria as the most protective standard for Montana’s wadeable streams and rivers, and in 2022 disapproving a first attempted repeal of numeric standards with a proposed weaker narrative nutrient criteria rule. This was a political decision which means that now under narrative standards, neither regulators or permittees will know harm is occurring until it’s too late, or for example, until algal blooms have covered a river bottom.
We’re now taking the EPA to court for unlawfully approved Montana’s rollback of numeric nutrient criteria.
2. What does the lawsuit claim?
- EPA’s conclusion that Montana’s proposed elimination of numeric nutrient criteria and reliance on narrative criteria will protect designated uses of applicable waters is arbitrary, capricious, and otherwise inconsistent with law.
- EPA’s approval of Montana’s revised nutrient standards is based on an incomplete water quality standards submittal and is inconsistent with agency rules and therefore arbitrary, capricious, and otherwise inconsistent with law.
- EPA violates Section 7 of the Endangered Species Act by failing to complete consultation prior to approving Montana’s revisions to nutrient criteria.
3. What is being requested through this litigation?
The litigation requests that the Court:
- Determines and declares that EPA’s October 3, 2025 approval of Montana’s elimination of numeric nutrient standards is unlawful, arbitrary, capricious, and otherwise not in accordance with the law
- Determines and declares EPA’s approval of revisions to Montana’s nutrient criteria violates the Endangered Species Act because EPA failed to complete consultation prior to approving the revision
- Enter an order vacating and setting aside EPA’s approval of Montana’s revised nutrient water quality standards and directing EPA to complete consultations with the U.S. Fish and Wildlife Service and to finalize federal water quality standards for nutrients in Montana that comply with the Clean Water Act.
4. What are Water Quality Standards?
Water quality standards (WQS) are provisions of state, territorial, authorized tribal or federal law approved by EPA that describe the desired condition of a water body and the means by which that condition will be protected or achieved. WQS entail three distinct and complementary parts: designated uses, criteria, and antidegradation policies. Water bodies can be used for purposes such as recreation (e.g. swimming and boating), scenic enjoyment, and fishing, and are home to many aquatic organisms. To protect human health and aquatic life in these waters, states, territories and authorized tribes establish WQS. WQS form a legal basis for controlling pollutants entering the waters of the United States.
5. What are Numeric Nutrient Criteria?
Numeric criteria are the means for protecting desired conditions (i.e., designated uses) of waterways. Numeric nutrient criteria are conservative, science-based judgments based on decades of science and monitoring defining, on a site-specific basis, what is necessary to protect healthy waterways from nuisance algal blooms and related harmful water quality conditions. Numeric criteria allow regulators and permittees to detect and reduce pollution before harm occurs, and to judge waterway health with a high degree of accuracy.
6. What is nutrient pollution?
Nutrient pollution (also known as “cultural eutrophication”), especially by Nitrogen and Phosphorus, is among the most pervasive sources of impairment to surface waters in the State of Montana, and nationally. Cultural eutrophication (often abbreviated as “eutrophication”) is the process of Nitrogen (N) and Phosphorus (P) contamination of surface waters from human-related sources that commonly add high levels of N and P, relative to what is natural background, so that the affected aquatic ecosystem is pushed out of balance to an unhealthy state.
7. What are the effects of nutrient pollution?
Nutrient pollution is a direct threat to Montana’s world-class wildlife, our multi-billion dollar outdoors economy, state fisheries, and other water users.
Nutrient pollution damages aquatic ecosystems in two basic ways: First, through an increase in the available amounts (supplies) of N and P that stimulate outbreaks (“blooms”) of nuisance algae; and second, through a shift in the proportion (supply ratio) of N relative to P supplies. Surface waters affected by nutrient pollution usually have both problems: the N and P supplies are elevated in comparison to background conditions, and the N:P ratio is skewed so that the aquatic communities have been pushed into what is referred to as “stoichiometric imbalance.”
Surface waters that receive high nutrient enrichment from raw or partially treated sewage are more vulnerable to adverse impacts of nutrient pollution in comparison to waters affected by other sources, because the majority (often ~80 to 95%) of the N and P is Ni and Pi, directly available for algal/plant uptake. The highly bioavailable N and P supplies in sewage-affected systems are much more potent in causing adverse impacts on receiving water resources. Risk of increased downstream impacts are greater as well, especially for partially treated sewage that includes high concentrations of nitrate which is highly soluble and can travel for hundreds of miles.
Nutrients, including in particular nitrogenous compounds, can lead to a variety of far-field effects on aquatic ecosystems, impacting water quality and biodiversity through eutrophication, algal blooms, oxygen depletion, and changes in the structure and function of aquatic food webs.
8. Why are numeric nutrient criteria important to nutrient pollution control?
Numeric nutrient criteria provide clear, quantitative goals for water quality, which improves water protection, restoration, and management by allowing for better monitoring, easier development of Total Maximum Daily Loads (TMDLs), and more effective permit writing. These standards help establish specific targets for nutrient levels like nitrogen and phosphorus to prevent issues such as algae blooms and protect designated uses like recreation and drinking water.
9. Why did the Montana Legislature rollback numeric nutrient criteria?
Ever since the State of Montana adopted numeric nutrient water quality standards in 2014, big polluters (oil, gas, mining industries and municipalities) have lobbied to diminish or delay the implementation of numeric nutrient criteria. Why? To escape the economic expense associated with the responsibility for controlling and treating their pollution and nutrient wastewater as necessary to protect Montana’s sensitive and finite water resources. Montana is a headwaters state and many of our waterways are pretty darn clean: treating wastewater to protect clean headwaters requires strong medicine, and yes, that entails a pay it forward proposition.
10. I’ve heard that numeric nutrient criteria were never attainable, and that’s why a general variance was originally approved to accompany criteria. Without variances, didn’t the State have to get rid of unattainable numeric nutrient criteria?
Numeric nutrient criteria in Montana are very stringent because waterways are sensitive and it is a headwaters state, where three transcontinental watersheds begin. Our waterways are inherently some of the cleanest and most natural conditions in the nation based on their geologic origin, and because a majority of our river miles are headwater streams with naturally low streamflow, they’re very sensitive to any unnatural nutrient loading.
Humans literally live in space and we have current technology to meet numeric nutrient criteria. However, this technology is expensive and has traditionally been used for the industrial sector, but not for municipal wastewater treatment facilities, largely due to cost.
Nutrient variances were never taken off the books, and individual variances remain available for any permittee who can demonstrate widespread and substantial economic harm. Anyone stating that variances aren’t available is telling a lie of omission. The State’s 2014 general variance was determined unlawful insofar as it allowed industrial polluters a free pass to pollute despite not experiencing widespread and substantial economic harm.
11. Isn’t non-point source nutrient pollution the real problem in Montana’s waterways?
Non-point source pollution means any source of pollution not regulated under the CWA’s pollution permit program. This includes agricultural operations, timber operations, septic systems, and a variety of other activities. Non-point nutrient pollution is the largest cause of river pollution across the Nation, including Montana. But gutting pollution protections that will add more pollution to our waterways isn’t a solution and will only make the problem worse.
That said, just because a permitted source is only a part of the problem doesn’t mean we don’t hold that source accountable to control their pollution and be a part of the solution.
Montana retains the ability to adopt regulatory control over non-point nutrient pollution, but has never done so. In fact, as recently as the 2023 and 2025 Legislative Session Montana has expanded the categories of non-point nutrient pollution exempt from regulation and pollution control.
Pointing fingers at unregulated sectors as a means to argue regulated sectors should do less is a recipe for precisely nothing meaningful being done to control existing pollution. It will inevitably lead to a race-to-the-bottom where every sector simply uses Montana’s rivers as sewers, with ratepayers, wildlife, and our outdoors economy feeling those externalized costs first.
12. What’s the big deal? I’ve read that Montana still has a narrative nutrient rule and its agencies can still make science-based decisions.
It’s true that Montana still has a narrative rule prohibiting harm, including harm from nutrient pollution, on the books as a matter of law. The problem is that narrative rule, specifically ARM 17.30.637, is general in character and lacks any site-specific methodology or guidance for how to translate the prohibition against causing harm to local water quality into practice.
Narrative prohibitions against causing harm, without an implementing rulebook, remain vague, imprecise, and naturally lead to permit writers making subjective decisions without clear metrics. Likewise, narrative prohibitions often require harm to occur before action is triggered. Waiting for harm to occur before requiring better pollution treatment is both bad policy and bad economics.
13. How does the repeal of numeric standards affect waterways that were previously determined impaired by nutrient pollution?
State law passed under the 2025 Legislature requires the elimination of numeric nutrient criteria from every aspect of water pollution control regulation, including prior pollution control and restoration plans (impairment determinations) and pending or future pollution permit actions. At the most practical level this categorical elimination will mean backsliding in existing pollution control plans as already-established pollution treatment upgrades or compliance plans based on numeric criteria are revoked and stayed.
Abandoning numeric criteria and reversing its usage in all clean water programs will stall a large slew of pending water pollution control projects across the state and make judging pollution restoration – or new pollution permit decisions – inherently less precise, despite conditions on the ground already being degraded.