Even the Bottom of the Grand Canyon is Now Contaminated

Fish and other creatures in remote stretches of the Colorado River are contaminated with levels of mercury and selenium known to harm wildlife.

By almost any calculation, the Colorado River at the bottom of the Grand Canyon is one of the most isolated places in the contiguous United States. Although about half a million people a year hike Grand Canyon trails, only a tiny fraction of them make the arduous trek to the bottom, almost a mile from the surface.

One might think that this inaccessibility protects the river’s unique ecosystems. But that’s wrong, says David Walters, lead author of new research conducted by the U.S. Geological Survey. "Pristine doesn't really exist in the world anymore,” explains Walters, “even at the most remote reaches of the Grand Canyon.”

The first comprehensive study of its kind has found that high levels of mercury and selenium

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