The Colorado River (seen here from Page, Ariz.) used to run all the way from Rocky Mountain National Park in Colorado through four other states and parts of Mexico before emptying into the Gulf of California (a.k.a. the Sea of Cortez). Today, the waters run dry long before they reach the historic river mouth, having been pulled and diverted by the states to grow crops, hydrate towns and cities, water lawns and fill up pools. Anything left over at the border between the United States and Mexico — and there rarely is much — is what's left for Mexico. Often the little water that is left is polluted with runoff from farms in the U.S. A multi-year drought has greatly reduced the amount of rainfall feeding the Colorado River, even as demand for its waters has grown, a situation guaranteed to pull the dry mouth of the river even farther up stream.