When National Park Service ecologist Jon O’Donnell gazed out the chopper window and laid eyes on a startlingly orange Arctic stream, one that only a year earlier had flowed crystal clear through the Brooks Range tundra, he knew the anomaly warranted a closer look.

Where fish and tiny life forms had flourished, a rust-orange slime now covered the stream bottom. There was no sign of fish. Macroinvertebrate numbers had plunged, O’Donnell recalled during a recent interview about the dramatic, newly released research that was spurred by that 2018 observation on the small tributary of the Akillik River in Alaska’s Kobuk Valley National Park. 

“This is kind of surprising,” he thought at the time: but not really uber-dramatic, since the Alaskan Arctic in this era of warming climate is always changing. O’Donnell had been monitoring those changes in his work at the Park Service’s Arctic Inventory and Monitoring Network. “Probably just a one-off case,” he initially assumed.

That all changed a year later, in 2019, when researchers choppered to a different remote site, the Agashashok River flowing through Noatak National Preserve, where O'Donnell and U.S. Geological Survey researchers were studying food-web impacts of carbon and nutrient releases from thawing permafrost. This time, the gin-clear water “looking almost like emeralds” flowed to where a seep was oozing orange into the river; and from there, “it turned brown-orange for miles,” O’Donnell told the Traveler.

“That was shocking …because of the size and the scale of the system, a much bigger river,” than the orange-stained stream he’d seen a year earlier. Over five years of observation, the Agashashok had been “perfectly pristine,” he said. “And then all of a sudden, it wasn't, and it was so abrupt that it was hard to understand what had happened at first glance.”

The subsequent research by federal and academic researchers revealed that at least 75 streams and rivers are “rusting,” contaminated with metals and minerals in far-flung reaches of the Brooks Range — including in Gates of the Arctic National Park and Preserve along with the Kobuk Valley park and the Noatak preserve — as permafrost thaws in Arctic warming that’s occurring about four times faster than in the rest of the world.

The study documented tainted waterways across nearly 600 miles of the Brooks Range, where researchers used remotely sensed imaging in addition to their field work, and tapped crowd-sourced observations from other researchers, pilots, wilderness guides, and rural communities, to inform the study. It was published in May in the journal Communications Earth and Environment. Study participants included scientists from NPS and USGS, the University of California at Davis and Riverside, Alaska Pacific University, University of Alaska Anchorage, and Colorado State University.

A Looming Threat

The bold orange hue — so striking that satellites in space can see it snaking across the tundra and boreal forest — is dramatic in itself. But the study’s initial findings encompass more troubling signs: Permafrost thaw is altering stream chemistry, with toxicity that threatens broad aquatic environments as the frozen underground loosens its hold on minerals and metals that have been entombed in ice for thousands of years.

Orange-pocked waterways were observed in watersheds of national wild and scenic rivers, including the Alatna, John, Koyukuk, Tinayguk, and Salmon, and in other Alaska river basins, all far from infrastructure or land use, such as mines and roads, whose proximity conceivably could have helped explain the contamination. The shift in water chemistry has “considerable implications” for Alaskan rural communities that depend on the streams and rivers for food and water, the study said.

It all adds up to “an emergent threat to stream ecosystems, water quality, and subsistence resources in Arctic Alaska and potentially other regions undergoing permafrost thaw,” it concluded.

Just The Latest Assault

"Orangeness" is just the latest ecosystem drama for Alaska. Locked in the tightening vise of climate change, it already is shouldering a catastrophe-laden burden of melting glaciers, eroding coastlines, thawing permafrost, buckling roadways, and intensified wildfires — just for starters.

Now come the rivers running milky orange and toxic, also under the thumb of a warming environment.

“Climate change and associated permafrost thaw appear to be the primary drivers of stream impairment, as shifts in stream color coincide with a period of rapid warming and increased snowfall,” the study said. “Our initial findings indicate that orange streams are an indicator of impaired water quality and are associated with declines in stream biodiversity and habitat degradation.”

Researchers are collecting more samples to shed light on how representative their initial observations and measurements are. The colorful waters were documented for the most part upstream of where people live and are on the rivers a lot, according to O’Donnell. But the taint already was on the radar of some Northern Alaska communities, and residents have raised questions about the issue at public meetings with federal regulators.

Weathering The Minerals

The scientists’ working theory ties the permafrost thaw to “weathering” of minerals, a process that is releasing high levels of iron, the instigator of the orange hue, as well as nickel, zinc, cadmium, and copper.

Permafrost is soil that’s been frozen beneath the surface for thousands of years, containing ice, rock, sand, and frozen plant and animal matter. Almost a quarter of land in the Northern Hemisphere is covered in permafrost, including vast sheets blanketing Alaska and the Arctic, according to NASA.

As permafrost thaws, water is infiltrating deeper into it and initiating the weathering of previously frozen sulfide minerals, essentially enabling a reaction with water and oxygen, scientists say. The result is highly acidic conditions that release the iron and other trace metals, which then flow out into surface streams.

“The water is getting deeper and it's interacting with constituents in the soil that have thawed," said Brett Poulin, an environmental chemist and metals expert at the University of California at Davis who was a principal investigator in the research. “The weathering reaction of sulfide minerals produces sulfuric acid, which helps to dissolve the metals and release them.”

One study site he visited resembled “a burn scar on a hillside,” he said. “All the vegetation is black, and there's water flowing over the dead vegetation.”

Researchers’ instruments measured elevated acidity coming from the seepage that was dramatically higher than safe levels found in uncontaminated waterways. “It’s like lemon juice,” Poulin said. 

“These are some of the most pristine locations, and really true wilderness, that we have in North America. And you're seeing impact in water chemistry that's actually common in a mine setting,” Poulin said, recalling acid drainage he’d seen coming from abandoned mines in the Colorado Rockies.

It was remarkable, he told the Traveler, “to see that in these national parks” so distant from any mines but with waters flowing “orange for many miles.”

An aerial view of the Kutuk River in Alaska's Gates of the Arctic National Park that looks like orange paint spilling into the clear blue water/NPS, Ken Hill

Downstream Concerns

The splashy new riverine color is more than a visual phenomenon for residents of Northwest Alaska’s isolated and sparsely populated communities where subsistence living is tied to the waterways. The metals that are emerging can be toxic to both fish and humans, the study noted, and threaten fish species like Dolly Varden, chum salmon, and whitefish.  

Researchers’ instruments measured high acidity in the Akillik tributary and found “dramatic declines” in diversity of macroinvertebrates and complete loss of Dolly Varden and Slimy Skulpin fish species.

“The potential impacts to these fish stocks is real and it could have implications on ecosystem health but also on human health, because these fish stocks are also used for subsistence fishing,” explained Poulin.

Direct absorption of toxic metals can accumulate in fish, damage their gills and DNA, and impede growth and survival, the study said. Researchers also worry about possible effects on their migration routes, if the fish simply choose to avoid the tainted waters.

Additional research will investigate how extensive and potent the problem is, but the report in the meantime warned, “Subsistence fisheries and drinking water supplies may become degraded in some Arctic river networks.” 

The Color Of Tang

Jack Reakoff, a longtime resident of Wiseman, population 11, gives talks for tour company visitors about hunting and subsistence living in his tiny hometown. Home is a seven-hour drive from a grocery store. Reakoff and his wife get their meat from hunting, mostly moose and caribou, and used to do a lot of fishing before the warming impact emerged in waterways.

Wiseman Creek runs from nearby Gates of the Arctic National Park and Preserve through his tiny village. It traditionally froze in winter and ran clear in summer after flushing out the seasonal melt of snow, ice and mud, Reakoff said. Grayling fish used to swim up into the drainage to feed.

But in 2017, a heavy rainstorm hit after a long dry period, he recalled. This time, the debris discharge was different. “It came surging down, and it was the color of Tang, orange juice,” he said. “And it just ran really heavy iron oxide.”

That iron load has returned every summer since. Along with the orange tint, mud and turbidity now clouds the stream through the summer. The grayling these days stay clear of the tributary — no surprise to Reakoff, given the oxidation he is witnessing.

“I have yet to detect a grayling moving in there since 2017,” he said, nor has he fished there since. And there appears scant hope of re-attracting the salmon smolt that used to feed there. Salmon in general have suffered dramatic population declines due to other habitat stressors, including warming waters, he noted, resulting in ongoing closures of subsistence harvesting on the Yukon River by Canada and Alaska officials.

And it’s not just Wiseman Creek, a tributary of the Koyukuk River, which is a tributary of the mighty Yukon.  

“The number of drainages we fish around here has been reduced because of this mineralized orange water,” Reakoff said. In particular, he’s seen the rusty taint in a stream eight miles to the north and another, the Hammond River, about five miles away. He used to visit both fishing spots, but now the grayling numbers there are vastly reduced. 

The shift comes on top of dramatically lower Yukon salmon runs that followed the severe marine heatwave in the North Pacific that started in 2015. In earlier years, Reakoff said, he’d travel three hours or so to the Yukon, passing numerous Indigenous villages along the river, and fish for salmon, pike and other species for a couple of days. “That’s where we got a lot of our fish,” he said.

The salmon decline and Yukon closures already had reduced Reakoff’s dependency on fish, and the more recent water quality changes have only increased the problem.

“We shifted away from fishing as much as we used to. You’ve got to eat,” he told the Traveler. “I’ve had to shift more to bird hunting.”

That means birds like grouse now account for more of the food he and his wife put on their table.

“People keep saying, ‘when's it going to stop?’” as the orange water returns each summer, he said. His reply: “Whenever the ice mass finishes melting out,” and empties the oxides and metals that have been buried for time immemorial. Reakoff serves on the Gates of the Arctic Subsistence Resource Commission and the Western Interior Alaska Subsistence Regional Advisory Council dealing with subsistence hunting and fishing issues. He said he’s long urged officials to get water samples from the tainted waterways to have baseline comparisons for the changes occurring.

The U.S. Fish and Wildlife Service, which manages U.S. national wildlife refuges, plans to conduct outreach to learn about local residents’ observations and to share science and implications emerging from the latest research, officials said. The population of the Northwest Arctic Borough, which encompasses some of the downstream rural communities, is more than 7,400 people, according to 2023 data from the state.

Rusty rivers map/UC Davis

The Footprint Of Warming

Even before the orange waterways showed up, troubling changes were arriving in tandem with permafrost melting in the Arctic. Soggy ground has given way to large slumps and slides, and Siberia is experiencing massive, eerily deep sinkholes and craters. Thawing also is exacerbating Alaska’s coastal erosion as softened soil becomes vulnerable to battering waves and weather.

The thaw also releases carbon and methane that had been tucked away in the frozen underground, scientists say. Those emissions now add to the very greenhouse effect that is melting the permafrost to begin with. In essence, permafrost becomes a big carbon source instead of the carbon sink it represents while still frozen.

The Arctic’s frozen ground contains nearly one-third of Earth’s stored soil carbon, according to the National Snow and Ice Data Center at the University of Colorado-Boulder. Projections indicate that permafrost potentially could release more greenhouse gases than already are in the atmosphere.

In the wild and scenic rivers, both the Alatna and the Salmon have experienced discoloration. The Salmon River’s water quality had been pristine, according to the Arctic Inventory and Monitoring Network, but its clear waters suddenly “turned distinctly orange-green” in the summer of 2019. In subsequent years, it “remained discolored with opaque turbid waters and orange stains on the banks,” a Park Service article stated.

As they conducted their research, O’Donnell and other scientists lamented in a November 2022 newspaper op-ed that, “Unfortunately the Salmon River is not what it once was.”

It still runs clear from its headwaters, but then for 55 miles is fed by alternating clear and orange tributaries, including “one grotesquely orange stream that thumps its contents into the Salmon just above its confluence with the Kobuk.” Numerous orange-bleeding ground seeps were seen “on slopes above the middle river that are surrounded by dead vegetation, including mature spruce trees.

“The Salmon remains wild, but its scenic attributes are degraded and the health of the ecosystem that it supports is in question,” the article stated.

O’Donnell said that while weathering likely accounts for the visible metal and mineral contamination in the Brooks Range elevations, lowland permafrost areas can experience contamination through microbial processes as the thaw occurs. 

A path to relief appears elusive with the current warming trends. Park Service data shows the national parks in central and northern Alaska saw an abrupt increase in the average annual temperature starting in 2014. Kobuk Valley National Preserve is projected to warm the most by 2100, when annual average temperatures could be 9.6° F to 18.6 °F warmer than the 1991-2020 baseline, according to Climate Central, an independent organization of scientists and journalists researching and reporting on climate.

Next Up

Park Service and U.S.G.S scientists and their university colleagues will collect additional water samples this summer. The continued research will seek to understand the scope of the orange streams across the national parks in the Arctic Inventory and Monitoring Network and quantify the effects of the released metals on water quality and more broadly on the food web and ecosystem.