March 22 is World Water Day, a time to reflect on the state of the world’s freshwater. The Colorado River is one of the most fully used—and heavily contested—waterways on Earth. It provides water for 30 million people and has many dams and diversions along its 1,450-mile (2,333-kilometer) path.
In its natural state, the river flowed all the way from the high plains of the Western U.S. to the Gulf of California in Mexico. But because it is so heavily tapped along the way for agriculture, industry, and municipal uses, it rarely reaches the ocean anymore. For a few short weeks in 2014, the U.S. and Mexico cooperated, allowing the waters to reach the ocean. An effort is underway to restore the flow permanently, but is unlikely to be implemented soon.
Related: Explore the Colorado River (map)