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January 7, 2021

One-Third of America's Rivers Have Changed Color Since 1984

Nicholas Institute for Environmental Policy Solutions

One-third of the tens of thousands of mile-long river segments in the United States have noticeably shifted color in satellite images since 1984. That includes 11,629 miles (18,715 kilometers) that became greener, or went toward the violet end of the color spectrum, according to a study in this week’s journal Geographical Research Letters. Some river segments became more red.

The study “is super cool and a bit mind-blowing (yet intuitive),” Martin Doyle, director of the Nicholas Institute's Water Policy Program, wrote in an email to the Associated Press. “It shows how most every aspect of our planet is being affected by humans, now including the basic color of our water. That’s pretty profound if you think about it.”

“It’s also important because it opens up the idea and potential of using river color as early-stage indicator, or warning of environmental change,” wrote Doyle, who wasn’t part of the study.