The length of the Colorado River is approximately 2,330 kilometers (1,450 miles).
From its source high in the Rocky Mountains, the Colorado River channels water over falls, through deserts and canyons, to the lush wetlands of a vast delta in Mexico and into the Gulf of California.
Its source in La Poudre Pass in Rocky Mountains is at elevation of 3,104 meters (10,184 feet).
In its natural state, the Colorado River poured about 20.1 cubic kilometers (16.3 million acre feet) into the Gulf of California each year, amounting to an average flow rate of 640 cubic meters (22,500 cubic feet) per second.
The Colorado River has an average depth of about 6 meters (20 feet).
The Colorado is joined by over 25 significant tributaries, of which the Green River is the largest by both length and discharge.
The river and its tributaries are controlled by an extensive system of dams, reservoirs, and aqueducts, which in most years divert its entire flow for agricultural irrigation and domestic water supply.
The Colorado River system is a vital source of water for 40 million people in southwestern North America.
The drainage basin or watershed of the Colorado River encompasses 640,000 square kilometers (246,000 square miles) of southwestern North America, making it the seventh largest on the continent.
About 618,000 square kilometers (238,600 square miles), or 97 percent of the watershed, is in the United States.
The Colorado River passing through no less than 11 different national parks.
The river is home to one of the seven natural wonders of the world, the Grand Canyon. The 446 kilometers (277 miles) of the river that flow through the Grand Canyon are largely encompassed by Grand Canyon National Park and are known for their difficult whitewater, separated by pools that reach up to 34 meters (110 feet) in depth.
At the lower end of Grand Canyon, the Colorado widens into Lake Mead, the largest reservoir in the continental United States, formed by Hoover Dam on the border of Arizona and Nevada.
Rivers and streams in the Colorado basin were once home to 49 species of native fish, of which 42 were endemic. Engineering projects and river regulation have led to the extinction of four species and severe declines in the populations of 40 species.
More than 1,600 species of plants grow in the Colorado River watershed, ranging from the creosote bush, saguaro cactus, and Joshua trees of the Sonoran and Mojave Deserts to the forests of the Rocky Mountains and other uplands, composed mainly of ponderosa pine, subalpine fir, Douglas-fir and Engelmann spruce.
The name Colorado originates from the Spanish word for red color. This is because of the red sandstone silt that would cover the river basin, making it look red. However, after the Glen Canyon Dam was built in 1963, the colored silt was trapped behind the dam and the river stopped looking red.
The Horseshoe Bend is a famous spot on the Colorado River, where it actually goes around a huge piece of rock in the shape of a horseshoe.
Prior to the construction of major dams along its route, the Colorado River fed one of the largest desert estuaries in the world. Spread across the northernmost end of the Gulf of California, the Colorado River delta’s vast riparian, freshwater, brackish, and tidal wetlands once covered 7,810 square kilometers (1,930,000 acres) and supported a large population of plant, bird, and marine life.
Today, conditions in the delta have changed. Like other desert river deltas, such as the Nile Delta and the Indus River, the Colorado River delta has been greatly altered by human activity.
Most of the major dams along the Colorado River basin were built between 1910 and 1970. One of the most well-known is the Hoover Dam [photo below] which was built in 1935.
The Colorado is now considered among the most controlled and litigated rivers in the world, with every drop of its water fully allocated.
Intensive water consumption has dried up the lower 160 kilometers (100 miles) of the river, which has rarely reached the sea since the 1960s.
Reduction of the delta’s size has threatened animals such as jaguars and the vaquita porpoise, which is endemic to the gulf.
The water of the river used to reach 29 °C (85 °F), but due to the dams it is now very cold all year around staying at about 8 °C (46 °F). Changes in temperature regime have caused declines of native fish populations.
Beginning with small bands of nomadic hunter-gatherers, Native Americans have inhabited the Colorado River basin for at least 8,000 years.
The river was first discovered by Europeans in 1539 by Francisco de Ulloa.
The river and its surrounding areas were first mapped in the early 1600s by Franciso de Bolanos, from the mouth all the way to the Gulf of California.
Several expeditions charted the Colorado in the mid-19th century – one of which, led by John Wesley Powell, was the first to run the rapids of the Grand Canyon.
Until 1921, the section of the Colorado River from its headwaters in Rocky Mountain National Park to its confluence with the Green River in Utah was known as the “Grand River.”
Famed for its dramatic rapids and canyons, the Colorado is one of the most desirable whitewater rivers in the United States, and its Grand Canyon section – run by more than 22,000 people annually – has been called the “granddaddy of rafting trips”.
The Mike O’Callaghan–Pat Tillman Memorial Bridge is an arch bridge that spans the Colorado River between the states of Arizona and Nevada. The bridge at nearly 270 meters (900 feet) above the water is the highest concrete arch bridge in the Western Hemisphere.
The Colorado River Aqueduct, a 242-mile-long channel completed in 1941 by the Metropolitan Water District of Southern California, carries water from the Colorado River to urban Southern California.