Alaska’s Orange Rivers

June 14, 2024 By: Spencer Durrant

Photo: Alaska Region U.S. Fish & Wildlife Service/Flickr

Not long ago, MidCurrent reported on the phenomenon of some Alaskan rivers turning orange. That news has since hit other outlets, renewing interest in this phenomenon, and what it could mean for fly fishing in the Last Frontier.

In short, some rivers in Alaska’s Brooks Range (a west-east mountain range located above the Arctic Circle) are turning alarming shades of orange due, in part, to melting permafrost. As permafrost melt accelerates in the Brooks Range region, minerals and metals locked away beneath the tundra are leaking into waterways.

There’s more of an impact on the water than just the nasty orange color, however.

These leaked minerals and metals are changing the pH of rivers, making them highly acidic and no longer suitable for aquatic vegetation or insects. It’s also been noted that dissolved oxygen levels are below thresholds that native fish need in order to survive.

A study on this phenomenon was recently published, and you can read it here. One part of the abstract that stands out, though is this: “Stream discoloration was associated with dramatic declines in macroinvertebrate diversity and fish abundance. These findings have considerable implications for drinking water supplies and subsistence fisheries in rural Alaska.”

Of all the implications of this problem, one that we rarely consider in the fly fishing world is the impact on rural communities in Alaska. Many native Alaskans rely on these river systems for subsistence fishing and drinking water. Not only are the fisheries themselves in trouble, but entire communities may find themselves in peril. Currently, researchers want to conduct more studies to identify exactly where the biggest mineral deposits are, in the hopes that problems can be contained or isolated, so as to pose a lower risk to humans and animals, according to Hatch Magazine

We’ll continue to keep the angling public informed on this topic as new developments arise.