But for the canyon, regulating the river has come with big environmental costs. The dam processes the Colorado’s mercurial flows - a trickle one year and a roaring, spiteful surge the next - into something less extreme on both ends. Engineers constantly evaluate water and electricity needs to decide how much of the river to let through the dam’s works and out the other end, first into the Grand Canyon, then into Lake Mead and, eventually, into fields and homes in Arizona, California, Nevada and Mexico. Since 1963, the Glen Canyon Dam has been backing up the Colorado for nearly 200 miles, in the form of America’s second-largest reservoir, Lake Powell. And the event that crystallized this odd, uneasy duality - that changed nearly everything for the canyon - feels almost small compared with all the geologic upheavals that took place before it: the pouring, 15 miles upstream, of a wall of concrete. The Grand Canyon is a planetary spectacle like none other - one that also happens to host a river that 40 million people rely on for water and power. Weather, gravity and plate tectonics warped and sculpted the exposed layers of surrounding stone into fluid, fantastical forms. A chasm was cleaved open, which the meandering water joined over time with other canyons, making one. For tens of millions of years, the crust pushed up and the rivers rolled down, grinding away at the landscape, up, down, up, down. Then a sea once again.Īt some point, energy from deep inside the Earth started thrusting a huge section of crust skyward and into the path of ancient rivers that crisscrossed the terrain. Eras and epochs ago, this place was a tropical sea, with tentacled, snaillike creatures stalking prey beneath its waves. The lands of western North America know well of nature’s cycles of birth and growth and destruction. “You know how you feel like when you go to the cemetery? That’s how I feel.” Seeing how much the canyon has changed, just in his lifetime, makes him “hugely depressed,” he said. John Weisheit, who helps lead the conservation group Living Rivers, has been rafting on the Colorado for over four decades. Our subjugation of the Colorado has already set in motion sweeping shifts to the canyon’s ecosystems and landscapes - shifts that a group of scientists and graduate students from the University of California, Davis, recently set out to see by raft: a slow trip through deep time, at a moment when Earth’s clock seems to be speeding up. But the river’s fate matters profoundly for the 280-mile-long canyon and the way future generations will experience it. The Colorado flows so far beneath the Grand Canyon’s rim that many of the four million people who visit the national park each year see it only as a faint thread, glinting in the distance.
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