Alaska’s Rivers Turn Toxic Orange: The Truth Behind the Color Change

Researchers from the National Park Service, the University of California at Davis, and the U.S. Geological Survey were stunned when they witnessed rivers in Alaska turning orange. After studying around 75 sites, they discovered that the rivers had changed from clear blue to rusty orange due to toxic metals released by melting permafrost.

Jon O'Donnell, lead author and an ecologist with the National Park Service's Arctic Inventory and Monitoring Network, shared in a statement with UC Davis , "The more we flew around, we started noticing more and more orange rivers and streams. There were certain sites that looked almost like milky orange juice." The study was published in the journal Communications Earth & Environment .

Brett Poulin, study co-author and a professor of environmental toxicology at UC Davis, noted that such changes were expected in mining areas, but they were unexpected in Alaska. Knewz.com explored how the study mentioned that Arctic soils, rich in organic carbon, nutrients, and metals like mercury, had released these toxic substances as the permafrost melted.

As the permafrost thawed, metals like iron, zinc, copper, nickel, cadmium, and iron were exposed, leading to the release of harmful minerals that had been buried underground. As a result, the rivers appeared to turn into something resembling milky orange juice.

Poulin told CNN , "What we believe we saw was this thawing of soil happening faster there than it would happen elsewhere. It was really an unexpected consequence of climate change." He added, "At several of the locations, the most drastic increases occurred between 2017 and 2018, which coincided with the warmest years on record at that point."

After further investigation, researchers found astonishing results when they tested the waterways. According to the U.S. Geological Survey, the pH level of the waterways was unexpectedly low, at 2.3, making them as acidic as vinegar. This toxic release of minerals into streams was directly tied to climate change and the melting permafrost.

Michael Carey, study co-author and a fisheries biologist with the U.S. Geological Survey, stated to Mongabay News , "Many of these affected streams served as important spawning grounds and nurseries for salmon and other fish species that were crucial to the ecosystem and local subsistence fisheries. Changes in water quality could have affected the entire food web."

This unusual phenomenon was first observed by researchers in 2018 in northern Alaska’s Brooks Range. Within a year, a tributary of the Akillik River in Kobuk Valley National Park had lost two local fish species — the Dolly Varden and the slimy sculpin.

Another study published by Water Resources Research suggested that Alaska was not the only place experiencing these surprising changes. Increased levels of metals such as sulfate, zinc, and copper had been observed in 22 of Colorado's mountain streams. Similar changes had also occurred in places like the Chilean Andes, the European Alps, and the Pyrenees in Spain. These changes occurred not just because of melting permafrost, but also due to reduced water levels. This raised concerns about how these changes would affect mountain water sources and aquatic life.