When ecologist Mike Carey flew his helicopter to retrieve a water sensor from a pristine Alaska stream in August 2018, he expected to find the same crystal-clear waters he’d left months earlier.
Instead, the bottom was blanketed in orange slime.
“Biodiversity just crashed,” Carey recalled, unable to find any fish or insects in waters that had teemed with life just one year before.
Scientists Have Now Documented 75 Orange Rivers Across an Area the Size of Texas
What started as an isolated incident has exploded into an environmental crisis visible from space.
According to research published in Nature Communications: Earth & Environment, scientists have now pinpointed 75 locations across northern Alaska’s Brooks Range where once-pristine streams have turned a cloudy, rust-orange color.
“The stained rivers are so big we can see them from space,” said Brett Poulin, an assistant professor of environmental toxicology at UC Davis who led the research.
These have to be stained a lot to pick them up from space.
The Water Is So Acidic It Could Dissolve a Penny
We visited one of these transformed streams in July to collect water samples.
The results were shocking.
Some samples registered a pH of 2.3, about as acidic as lemon juice, compared to the normal pH of 8 for Arctic rivers. That’s roughly 100,000 times more acidic than these waters should be.
But it’s not just the acidity that’s alarming scientists.
Toxic Metals Are Leaching Into Drinking Water for 8 Alaska Native Villages
Water testing revealed elevated levels of iron, zinc, nickel, copper, cadmium, and lead, some at concentrations toxic to aquatic life.
“We see a lot of different types of metals in these waters,” said PhD student Taylor Evinger who analyzed the samples. “One of the most dominant metals is iron. That’s what is causing the color change.”
The implications are dire for communities that depend on these rivers.
Eight Alaska Native villages in the western Brooks Range rely on these waterways for drinking water and fishing. The Wulik River, which terminates at the village of Kivalina, home to just over 400 people, is among the affected waterways.
“We are always worried about drinking water,” said Tribal Administrator Millie Hawley.
The Culprit? Arctic Permafrost Is Thawing 4 Times Faster Than the Rest of the World
The Arctic is warming at an unprecedented rate, four times faster than the global average.
This extreme warming is causing permafrost that has been frozen for thousands of years to thaw, exposing minerals that react violently when they contact water and oxygen for the first time in millennia.
“It’s really an unexpected consequence of climate change,” Poulin explained.
Think of it like rust forming on metal, but happening to entire river systems.
Famous Rivers That Inspired Books Are Now “Completely Collapsing”
The transformation is heartbreaking for those who know these waters.
When author John McPhee paddled the Salmon River in 1975 for his Alaska classic “Coming into the Country,” he described it as containing “the clearest, purest water I have ever seen flowing over rocks.”
The government designated it a wild and scenic river for its “water of exceptional clarity.”
Now?
“It was a famous, pristine river ecosystem,” said ecologist Patrick Sullivan, “and it feels like it’s completely collapsing now.”
Fish Are Vanishing and Scientists Fear It’s Permanent
At one monitoring site in Kobuk Valley National Park, researchers documented the complete disappearance of fish species shortly after the orange water appeared.
Juvenile Dolly Varden trout and slimy sculpin, species critical for subsistence fishing, simply vanished.
“Those orange streams can be problematic both in terms of being toxic but might also prevent migration of fish to spawning areas,” lead researcher Jon O’Donnell warned.
The changes may be irreversible.
The Orange Plague Started in 2008, But It’s Spreading Fast
While scientists first noticed the orange waters in 2018, satellite imagery reveals the transformation actually began as early as 2008.
“The issue is slowly propagating from small headwaters into bigger rivers over time,” O’Donnell said. “When emergent issues or threats come about, we need to be able to understand them.”
The timing coincides with Alaska’s warmest years on record.
Researchers noted the most dramatic color changes occurred between 2017 and 2018, when the state experienced unprecedented heat and unusually high snowfall that further insulated the ground and accelerated permafrost thaw.
This Isn’t Just Happening in Alaska
Similar phenomena are appearing across the Arctic.
Researchers spotted two orange streams while flying from British Columbia to the Northwest Territories. Studies in Colorado’s Rocky Mountains show similar metal contamination in mountain streams, with increases in sulfate, zinc, and copper concentrations over the past 30 years.
The Chilean Andes, European Alps, and Pyrenees in northern Spain have all documented comparable changes.
What Happens Next Could Affect Millions?
“As the climate continues to warm, we would expect permafrost to continue to thaw,” O’Donnell said. “Wherever there are these types of minerals, there’s potential for streams to be turning orange and becoming degraded in terms of water quality.”
The research team is in year two of a three-year grant to understand which areas might be at risk next.
But one thing is already clear: what’s happening in Alaska’s rivers is a preview of changes that could sweep across the entire Arctic as the planet warms.
Alaska’s environmental disasters have global implications, from the Exxon Valdez oil spill that forever changed marine ecosystems to today’s orange rivers serving as a stark warning about accelerating climate change impacts.
The Bottom Line: A Pristine Wilderness Is Rusting Away
Roman Dial, a biology professor who spent a month in the Brooks Range in 2020, put it bluntly: “All the hardrock geologists who look at these pictures, they’re like, ‘Oh, that looks like acid mine waste.'”
But there are no mines here.
Just the Earth itself, bleeding orange as ancient ice melts away.
Update: Scientists are currently studying whether rivers can recover if cold weather returns and permafrost refreezes. Early results suggest the damage may be permanent in many watersheds. We’ll update this story as new research emerges.
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