COLORADO RIVER

Location: 35N 115W (western USA); length: 2300 kilometres (1400 miles); drainage basin: 630,000 square kilometres (245,000 square miles)

The Colorado is one of North America's largest rivers, flowing from the Rocky Mountains to the Gulf of California. It is famous for the Grand Canyon and the Hoover Dam. There are no major cities situated beside the Colorado.

The headwaters of the Colorado are in the high mountains of the Rockies, in Rocky Mountains National Park.

The Upper Colorado

From here it flows first south and then west, south of the Wasatch mountains and across the western part of the Colorado plateau. Its main tributary is the Green River.

The Green River in Canyonlands National Park.

As it crosses the high, arid plateau, the Colorado creates one of the most spectacular canyonlands landscapes on Earth.

The sediment produced by erosion of the red plateau sandstones made the natural river a red color, hence the Spanish explorers called it the Colorado (Red River).

The Colorado finally enters the Pacific Ocean in the Gulf of California, Mexico.

The steep course of the Colorado makes it completely unsuitable for navigation. In fact exploring the river was extremely hazardous because of the many sections of white water.

When it was first explored by General Powell in 1879, several people lost their lives in the turbulent waters. However, the river has long been tamed by the construction of many dams, the largest being the Hoover dam and the Glen Canyon dam.

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The Glen Canyon dam.

The Hoover dam on the Arizona-Nevada border near Boulder City.

These have created huge reservoirs, whose 21 billion cubic m (700 billion cubic feet) are able to supply hydro electric power, irrigation water to farms (such as the Imperial Valley of California), and drinking water to cities as far away as Los Angeles.

Because the Colorado brings water to a large area of parched land, gaining the rights to use the water has always been of paramount interest to Mexico and the Colorado states. Allocating the waters of the Colorado has proved fraught with difficulties. The water is so fully allocated that the river no longer flows to the sea. Mexico complains that the way the U.S. abstracts water leaves the water reaching Mexico too saline for use and the U.S. states argue between themselves over water rights. At the same time, increases in the population in the South West means that there is continued pressure to abstract every last drop, much to the detriment of the environment.

The Parker dam down river of the Hoover dam.

Recreational use of the Colorado near Imperial Dam on the Arizona / California border.