A thick, white band of newly exposed rock face stretches high above boaters’ heads at Lake Powell, creating a sharp contrast against the famous red desert terrain as their vessels weave through tight canyons that were once underwater. It's a stark reminder of how far the water level has fallen at the massive reservoir on the Utah-Arizona border. Just last year, it was more than 50 feet higher. Now, the level at the popular destination for houseboat vacations is at a historic low amid a climate change-fueled megadrought engulfing the U.S. West.