Deep in the Grand Canyon, on land that Havasupai Native Americans have called home for generations, is a place known as Beaver Falls. It’s an unimaginative name for an otherworldly landscape, where turquoise water tumbles over a series of terraces gouged into red desert walls. To legally reach the falls, you have to pay the Havasupai $140, hike ten miles to the tribe’s campground, then hike an additional four miles to the waterfall. The camping and hiking permits are one of the tribe’s few sources of revenue, and help ensure that Beaver Falls stays protected...