Montana is famous for its waterways, speckled with sparkling high-alpine lakes and ribboned with trout-filled streams. It’s also the birthplace of several major rivers, including the Missouri, and home to Flathead Lake, the largest natural freshwater lake east of the Mississippi. But now, the Montana Legislature, with the Environmental Protection Agency’s backing as of October, is rolling back protections for these waters.

Montana was once a leader when it came to regulating pollution in its waterways. In 2014, it became the first state in the country to impose numeric water-quality standards on dissolved nitrogen and phosphorus, two major sources of nutrient pollution, in wadable streams as well as some river segments.

When excessive nitrogen and phosphorus, generally from mining, municipal wastewater and agricultural operations, enter waterways, they can trigger a flurry of slimy green algal growth. This is more than just an eyesore: Such algal blooms deplete oxygen in the water — which can cause massive fish die-offs — choke off its depths from sunlight and release toxins capable of sickening humans who consume the tainted water.

Water-quality standards are the objectives that each state or tribe sets, with the approval of the Environmental Protection Agency, to ensure that its waters are safe for human health and aquatic life. They dictate the state’s environmental water policy regarding everything from mobilizing cleanup efforts to issuing permits to point-source polluters — entities that release wastewater into the environment through a pipe or a ditch. Under these standards, the legal nutrient pollution thresholds for water bodies can be defined either numerically or narratively. Numeric standards set the upper limits of permissible nutrients, usually capped at levels before algal blooms occur, while narrative standards describe what, ideally, clean waterways should look like based on water-quality degradation parameters.

Earlier this year, however, state legislators passed a trio of bills that repealed the numeric standards, leaving the state with existing narrative standards. According to environmental groups and water-quality experts, numeric standards are generally considered less protective than the numeric ones. That’s because numeric standards kick in preventively, forcing polluters to treat their waste long before degradation becomes apparent. Narrative standards, however, take effect only after problems are already visible. Numeric standards are quantifiable — and therefore, enforceable — benchmarks of maximum pollution levels, whereas narrative standards are more subjective, affording both polluters and regulators greater flexibility and discretion.

Narrative standards, however, take effect only after problems are already visible.

“There’s a lot of uncertainty right now about this shift to narrative standards,” said Scott Bosse, the Northern Rockies regional director of the nonprofit American Rivers. No one knows how Montana’s Department of Environmental Quality (DEQ) will officially implement the new standards.

The DEQ claims that narrative standards are more efficient than numeric standards when it comes to preventing excessive pollution. The department said it plans to look at each body of water on a case-by-case basis, tailoring its anti-pollution policies according to the local hydrological and ecological context.

“We’re really trying to find the best site-specific controls,” said Andy Ulven, chief of the DEQ’s Water Quality Planning Bureau. Under the new standards, his department will rely on the health of aquatic indicator species, such as mayflies, algal levels and dissolved oxygen content to shape the state’s water policy. Dissolved nitrogen and phosphorus levels will still be part of the conversation, he added, “but we need to look at the bigger picture.”

Critics are not convinced, arguing that the 2025 legislation is vague and overly broad. Nine watchdog groups have called for a moratorium on permits until a more specific plan is for implementing narrative standards is in place.

This isn’t first time Montana has tried to repeal its numerical nutrient standards. But the EPA rejected previous attempts in 2020 and 2022, saying the new standards would run afoul of the Clean Water Act. This year, however, the agency did an abrupt U-turn, rubberstamping the new rules on Oct. 3, during the government shutdown.

Even though Montana first set numerical criteria for nutrient pollution in 2014, the state never enforced them in earnest. Instead, the DEQ extended expiring permits rather than revising them to comply. Now, over two dozen permit holders are awaiting renewals, including Montana’s largest cities, Billings and Missoula, as well as towns like Kalispell and Whitefish, whose waterways drain into Flathead Lake.

Flathead Lake, from Wild Horse Island. The lake is the largest natural freshwater lake east of the Mississippi. Credit: Tony Bynum

The old numeric standards would have been more costly to adhere to, requiring massive infrastructure upgrades to the state’s generally outmoded facilities. But Guy Alsentzer, executive director of Upper Missouri Waterkeepers, argued that revamping wastewater treatment technology will be worth it for the long-term health of Montana’s waterways and residents. “Nobody wants to pay for it,” he said, adding that “you don’t mess with your goalposts if you have an implementation problem.”

Over 35% of Montana’s river miles and 22% of the lakes overseen by DEQ are considered impaired, due to pollution from sewage, industrial waste and fertilizers. Environmental groups worry that renewing a flurry of permits under the new, more permissive standards could simply release the floodgates for yet more nutrient contamination.

“One of the take-home messages here is that the states will see EPA as receptive to these rollbacks of Clean Water Act protections.”

Since Oct. 3, Montana has advanced just one new permit renewal, for the Sibanye-Stillwater platinum and palladium mine along the East Boulder River in the southern part of the state. The original 2023 permit set stringent numeric ceilings on nitrogen pollution, a byproduct of dynamite use, that the Stillwater Mining Company had to meet in 10 years. But the new permit, still working its way through the approval process, allows for more than a 50-fold increase in the amount of nitrogen that the mine operators can spew here and now. All eyes are on Sibanye-Stillwater as a case study for how rivers will fare under the new narrative standard rules, Alsentzer said.

Montana’s rollback of its water-quality standards comes at a time of heightened attacks on the Clean Water Act nationwide. Last month, the Trump administration proposed removing federal protections from over 80% of the nation’s wetlands.

As the federal government dismantles environmental protections, critics say states should be doing more, not less, to defend their rivers and lakes. Montana’s success in repealing its stricter pollution standards is likely to encourage other states to take advantage of a more lenient EPA. “One of the take-home messages here is that the states will see EPA as receptive to these rollbacks of Clean Water Act protections,” said Andrew Hawley, a staff attorney at the Western Environmental Law Center.

In the meantime, Montana’s waters remain increasingly vulnerable. “It’s so mind-boggling to me that both the state and the EPA would want to put Montana’s clean water at risk by shifting to narrative standards,” American Rivers’ Bosse said. “We’re basically slitting our own throat.”

This story was made possible with support from the Institute for Journalism & Natural Resources.

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