Montana rivers like the Yellowstone are seeing increasing pressure from recreationists at the same time that development is increasing in the region.Brett French

As Montana’s population has grown, development, drought, disease, invasive species and recreation have combined to put more and more pressure on the state’s water resources in all their forms — from rivers, lakes and streams to groundwater.

It’s a pattern Dave Stagliano saw before, when he lived in Colorado in the mid-1990s. Now, the president of the Montana Chapter of the American Fisheries Society worries Montana is traveling in a similar direction.

“No (fisheries biologist) is disputing any of the bad changes that are coming down the pike,” he said.

“We can’t ignore the fact that fishing pressure is one of those things, on top of environmental stresses like some of the drought years, that can really put a fishery in jeopardy,” he added.

Two recently published studies highlight new dangers facing all waters in the nation that are less obvious than crowded boat launches or hook-scarred trout.


Earlier this year, the Environmental Working Group released a study that took samples from 500 fish across the United States to analyze them for “forever chemicals,” or toxic PFAS (per- and polyfluoroalkyl substances). PFASes have been used since the 1940s as coatings to resist heat, oil stains, grease and water, according to the Environmental Protection Agency, and do not break down in the environment. Firefighting foams are another source of the chemicals.

The Environmental Working Group study estimated eating one serving of freshwater fish a year could equal a month of drinking water laced with PFAS. The U.S. Food and Drug Administration has not established a safe level for the chemicals in fish.

In drinking water, the Environmental Protection Agency recommends limits ranging from .02 parts per trillion to .004 ppt for the most common PFAS. According to the study, even low doses of PFAS have been linked to an increased risk of certain cancers and suppression of the immune system.

In Montana, fish sampled for the study found levels as high as 76,000 ppt in a Missouri River channel catfish downstream from Great Falls and 55,490 ppt in a lower Yellowstone River channel cat. A Stillwater River brown trout had 24,306 ppt. For comparison, a sample from a mountain whitefish on the Clark Fork River caught downstream from Missoula had 1,387 ppt of the forever chemicals.

A fishing access site along the Yellowstone River is crowded with vehicles during the height of the summer floating season.Brett French


Another recently published study in the journal “Science Advances” compiled data from more than 6,100 streams across the United States that were sampled for 27 years by federal agencies.

The results showed urban and agricultural streams losing tiny plants and bugs sensitive to pollutants. The study also found the differences between streams draining forests, wetlands and grasslands versus those in urban and agricultural areas have grown larger over time. Urban and agricultural streams have lost the few sensitive species of bugs and plants they once had while gaining those tolerant to disturbance.

Although the federal Clean Water Act was passed in 1972, the scientists wrote, “Despite decades of regulatory and management actions aimed at reducing freshwater contaminants and restoring freshwater habitat, we observe continued degradation of the communities in urban and agricultural streams and no evidence of widespread recovery of sensitive aquatic taxa across U.S. stream networks.”

Based on the findings, the study authors called for change.

“Our results suggest that current legislation and conservation and restoration land use practices have not been enough to stem the pressures on these communities. Without protections for stream communities, especially those in (human) modified habitats, they likely will continue to degrade and perhaps lead to a loss of ecosystem functions and services.”


Chemicals in the water can build up over time in animals and fish.Brett French

Any time the balance of an ecosystem is upset, you have to take heed, Stagliano said, adding, “We need to be proactive.”

The Montana Chapter of the American Fisheries Society, an organization representing around 200 fisheries scientists in the state, focused its 2023 meeting in Butte on “Population growth and its effects on Montana’s fisheries and aquatic resources.”

Although the scientists are not able to enact policy changes, their work can inform those in a position to take action, Stagliano noted.

Not always willing to stand on the sidelines, the group has taken stances on policy issues in the past. The chapter advocated for the bypass channel around Intake Diversion Dam on the lower Yellowstone River to provide fish passage for endangered pallid sturgeon, and on a national level endorsed the removal of Snake River dams to help struggling populations of ocean-going salmon and steelhead.

Water isn’t just a resource issue. Past estimates by the Department of Fish, Wildlife & Parks have estimated the annual economic value of money spent on fishing activities amount to more than $900 million. That doesn’t count money generated by rafting outfitters or pleasure boaters.


Remote mountain streams have retained more diversity in its aquatic life that streams in urban and agricultural areas.Brett French

One organization that can push to protect water resources in Montana is the Upper Missouri Waterkeeper, created in 2013. The group’s director, Guy Alsentzer, sees the “Science Advances” study as applicable to what’s going on in Montana. He pointed to recent reports about the decline of brown trout in the upper Clark Fork River downstream from Butte, dead whitefish and “zombie trout” suffering from proliferative kidney disease outbreaks as harbingers of worse to come.

“There are in fact big shifts happening in (macroinvertebrate) communities, including Montana’s, and those shifts are likely to have a direct and significant impact on trout/fishery populations, particularly when taken in conjunction with cumulative decline in water quality and habitat conditions,” he wrote in an email.

Alsentzer said national and state agencies need a paradigm shift to address the problems scientists like fisheries biologists are pointing out. That’s why his group is championing “the importance of using proven regulatory mechanisms under state and federal law to protect invaluable headwater streams,” he added. Protecting the water quality and habitat in those places is essential “to the viability of historic aquatic life.”

Stagliano agreed, saying he hopes politicians will heed what scientists are finding.

“As we encroach on the aquatic resource, as those developments come closer and closer to riparian areas, we have a scientific backbone to stand on,” Stagliano said. “We know that a lot of those developments, especially away from cities — those suburban outliers, they’re on septic tanks and septic systems. We all know septic tanks fail from time to time and that winds up in our river. It’s never good to be adding sewage and nutrients to our fisheries. It won’t manifest itself usually in a fish kill, but like we see on the Gallatin near where Big Sky is … it may pass muster on a (Department of Environmental Quality) level, but we’re seeing algae blooms because of the warming water temperatures. And what was working 10 years ago isn’t working now. And eventually that’s going to catch up to the fishery in terms of bug hatches that may be gone down the road and the trout will suffer.”

Exploring the Yellowstone River by boat in Eastern Montana.