The Colorado River begins in the Rocky Mountains, collecting snowmelt as it meanders through an alpine valley. Across a vast swath of Colorado, Wyoming and Utah, the river grows as it takes in major tributaries: the Gunnison, the Dolores, the Green and others.

The Colorado River Basin encompasses more than 246,000 square miles in seven U.S. states and northern Mexico. On its 1,450-mile journey, the river scours the Grand Canyon and flows into the country’s two largest reservoirs.