Watershed Reports – Colorado River Basin Summary

The Colorado River is one of the arid American West’s most important suppliers of water. Its basin drains an area roughly the size of France and provides water to seven states in the US – Wyoming, Colorado, California, Nevada, Utah, New Mexico, and Arizona – as well as two states in Mexico.

The Colorado River itself has humble beginnings as billions of snowflakes, high up in the Rocky Mountains near La Poudre Pass. The headwaters of the Colorado are primarily formed by the melting of this snow. This young, creek-like Colorado cascades down the western side of the continental divide, where it is fed by the Blue River near Kremmling and the Eagle River near Eagle. On its way to its meeting with the cold Roaring Fork River, the Colorado carves away at the crumbly and beautiful Glenwood Canyon. As it passes through Glenwood, it’s not uncommon to see a kayaker or even a surfer atop the man-made wave near Dairy Queen.

The Colorado, now moving at a slower pace and colored by the sediment for which it was named, meanders along western Colorado, through tiny towns built around the river, like New Castle, Rifle, Parachute, and De Beque. After passing through the long and twisting De Beque Canyon, the river joins up with another large river, the Gunnison, in the aptly-named city of Grand Junction. Here, the river provides water for lazy canyon rafting and hot-weather wineries.

As it exits the state of its birth, the Colorado River enters a region known as the Colorado Plateau. This area is dominated by uplifted sandstone and slickrock. Like an eccentric architect, the river sculpts canyons, arches, and hoodoos out of the rock. The river is bolstered by water from the Dolores River as well as a major addition from the Green River on its way to one of its largest obstacles, the Glen Canyon Dam. The dam, built in 1966, holds back nearly two years worth of the river’s normal flow in the form of Lake Powell. The lake is popular for boaters, and owes its twisting sandstone beauty to the canyon that it covers. As the river flows out of the lake and through the dam, it generates a large amount of hydroelectric power.

Below Lake Powell, the river flows through what may be its greatest achievement: the Grand Canyon. Over millions of years, the powerful Colorado has carved a gorge into the earth nearly one mile deep and 277 miles long.

The river then makes a quick side-trip through Nevada. While the time it spends in Nevada may be just a blip in the river’s radar, the water it provides to Lake Mead, contained by the massive Hoover Dam, provides water for almost the entire city of Las Vegas. Below its two major reservoirs, the Colorado loses much of its red-brown color due to massive sediment deposition.

The now bluish-green river continues in a markedly southward path, forming the border between Arizona and California. At this point nearly all of what remains of the Colorado is diverted either to supply the many large cities in Arizona’s desert or to fill the All-American Canal, a main water source for California’s agricultural Imperial Valley.

The remnants of the river trickle through Mexico, toward their final destination in the Gulf of California. Occasionally, the river receives a small boost from the Gila River near Yuma, but much of this water is then used to irrigate the fields of the Mexicali Valley. Often, the entirety of the river will be used up before reaching the ocean, and then small amounts will re-emerge nearer to the coast in the form of irrigation return flows.

1,450 miles from its origin, the Colorado finally meets the Gulf of California. Since 1960, the Colorado River has made it all the way to the Gulf only a handful of times. The Colorado River Delta, an ecologically valuable estuary, now gets most of its water from the much smaller and shorter Hardy River.