Source: http://reuters.com/article/2015/09/17/us-climatechange-summit-earthprints-usa-idUSKCN0RH1A020150917

Where the Colorado River falls from the snow-capped Rocky Mountains into the arid U.S. Southwest, lies Lake Powell.

More than 150 meters deep in places and with narrow side canyons, the shoreline of the lake is longer than the entire West Coast of the United States. It extends upstream into Utah from Arizona's Glen Canyon Dam and provides water for Nevada, Arizona and California.

But a severe drought in recent years, combined with the tapping of the lake's water at what many consider to be an unsustainable level, has reduced its levels to only about 42 percent of its capacity, according to the U.S. space agency NASA.