As US Dams Come Down, Drought-Struck Colorado Builds New Ones

The Chimney Hollow Dam looks ancient in its simplicity, like a Neolithic mound. The largest dam built in the US in a quarter century, it is not a monumental wall of concrete like the Hoover Dam. Instead, it’s a triangular prism of granite boulders, 350 feet high and 3,700 feet long, stretching across a dry valley in northern Colorado. Two white pipes snake up the far side of the valley and out of sight, heading toward the Colorado River, about 30 miles away. On April 20 engineers turned a valve and began pumping water from the river and putting it ...