How much water is apportioned to each State in the Colorado River Basin?
The Colorado River Compact did not apportion water to any State. On October 11, 1948, the Upper Basin States entered into the Upper Colorado River Basin Compact, which apportioned use of the Upper Basin waters among them. The compact permits Arizona to use 50,000 acre-feet of water annually from the upper Colorado River system, and apportioned the remaining water to the Upper Basin States in the following percentages: Colorado, 51.75 percent; New Mexico, 11.25 percent; Utah, 23 percent; and Wyoming, 14 percent. The Lower Basin States of Arizona, California, and Nevada were not able to reach agreement. In 1952, Arizona filed suit in the United States Supreme Court to determine how the waters of the Lower Basin should be divided. In October 1962, the Court ruled that of the first 7,500,000 acre-feet of mainstem water in the Lower Basin, California is entitled to 4,400,000 acre-feet, Arizona 2,800,000 acre-feet, and Nevada, 300,000 acre-feet. The United States has contracted with the Stat
