This  Information was taken from:

http://www.watereducation.org/doc.asp?id=1025

Cutting through 1,450 miles of mountains and deserts, the Colorado River supplies water to over 25 million people and helps to irrigate 3.5 million acres of farmland.

More water is exported from the Colorado River’s 250,000 square-mile basin than from any other river basin in the world.

The river’s waters are diverted to supply numerous regions including the Salt Lake Valley in Utah; the Rio Grande Basin in New Mexico; Cheyenne, Wyoming; the southern coastal plain and irrigation districts in California; and over the Continental Divide to the city of Denver. 

Waters of the Colorado River were first developed by the Anasazi Indians in northwestern New Mexico as early as 600 A.D. followed by Spanish missionaries in the mid-16th century.

By the mid-1800s, the Church of Jesus Christ of Latter Day Saints (Mormons) settled in Utah and began developing the Green and Virgin rivers – major tributaries to the Colorado River.

In 1869, geologist John Wesley Powell led a party that became the first to successfully explore and map the Green and Colorado rivers.

A one-armed Civil War major, Powell led three boats down the Colorado through the Grand Canyon on two expeditions, proving the trip could be accomplished. His explorations helped open the gateway to the West – and development of the Colorado River

–River.