Colorado River - Course, Elevation summary

River in SW USA; rises in the Continental Divide, N Colorado; flows through Utah and Arizona (via Marble Canyon and the Grand Canyon), and forms part of the Nevada–Arizona, California–Arizona and Arizona–Mexico borders; empties into the Golfo de California; length c.2350 km/1450 mi; major tributaries the Gunnison, Green, San Juan, Little Colorado, Gila, Virgin; used extensively for irrigation, flood-control, and hydroelectric power (Hoover, Davis, Parker and Imperial Dams).

Colorado River
Map of the Colorado Watershed
Mouth	Gulf of California
Basin countries	United States, Mexico
Length	2,330 km (1,450 mi)
Source elevation	~2800 m (~9000 ft)
Avg. discharge	1206 m³/s (42,600 ft³/s)
Basin area	629,100 km² (242,900 mi²)

The Colorado River is a river in the southwestern United States and northwestern Mexico, approximately 1,450 mi (2,330 km) long, draining a part of the arid regions on the western slope of the Rocky Mountains. The natural course of the river flows into the Gulf of California, but the heavy use of the river as an irrigation source for the Imperial Valley has desiccated the lower course of the river in Mexico such that it no longer consistently reaches the sea.

Course

The Colorado River's headwaters are located in Rocky Mountain National Park, just west of the Continental Divide. (There is some authority for considering the headwaters of the Colorado River, and its main source, to be the Green River which rises in Sublette County, Wyoming. The Green River is practically the same size as the Colorado, formerly known as the "Grand" River at their confluence near Moab, Utah). Shortly thereafter the river meets the Eagle River and parallels I-70 through Glenwood Canyon and then passes through the city of Glenwood Springs where it is joined by the swift flowing Roaring Fork River.

Once inside Utah, the river turns south partially forming the southern border of Arches National Park near Moab, Utah, then passes by Dead Horse Point State Park and through Canyonlands National Park where it is met by one of its primary tributaries the Green River. Just south of the town of Page, Arizona, the river forms the dramatic Horseshoe Bend, then at Lees Ferry is joined by another tributary, the warm, shallow, muddy Paria River, and begins its course through Marble Canyon.

At the southern end of Marble Canyon, the river is joined by another tributary, the Little Colorado, and the river then turns abruptly west directly athwart the folds and fault line of the plateau, through the Grand Canyon, which is 217 miles long (349 km) and from 4 to 20 miles wide (6 to 30 km) between the upper cliffs. Along the California-Arizona reach of the river, two additional dams are operated to divert water for agricultural irrigation supplies: Palo Verde Diversion Dam and Imperial Dam. Here, the Colorado River ranges in width from 700 to 2500 feet (210 to 760 m) and from 8 to 100 feet in depth (2 to 30 m).

Below the Black Canyon the river lessens in gradient, and in its lower course flows in a broad sedimentary valley's distinct estuarine plain upriver from Yuma, where it is joined by the Gila River.

The lower course of the river, which forms the border between Baja California and Sonora, is essentially a trickle or a dry stream today due to use of the river as Imperial Valley's irrigation source.

Elevation summary

Approximate heights above sea level at several key locations:

Feet	Meters	Location
9000	2750	Colorado headwaters (Rocky Mountains)
6100	1850	midway to Colorado-Utah border
4300	1300	Colorado-Utah border
3850	1170	midway to Utah-Arizona border
3700	1130	Utah-Arizona border (Wahweap Bay)
3000	900	midway to Grand Canyon (Rider Point)
2800	850	Grand Canyon North Rim
2500	760	Grand Canyon South Rim
1200	365	Lake Mead
600	183	after Hoover Dam
485	150	California-Nevada-Arizona border
100	30	California-Arizona-Mexico border

Note that the significant difference between the present height of the Grand Canyon (about 8000 ft; 2440 m) and the levels at which the river enters/exits it gives rise to the geologic theory that its upheaval must have begun around the same time the river began flowing through it and eroding it (since rivers do not run uphill long distances, it would have followed some other path around the upheaval).

The Colorado River is a major and in some cases life-sustaining source of water for irrigation, drinking, and other uses by people living in the arid American southwest. Allocation of the river's water is governed by the Colorado River Compact. Several dams have been built along the Colorado River, beginning with Glen Canyon Dam near the Utah-Arizona border. The lower river from Davis Dam to Yuma is navigable by large paddlewheel boats and river barges, but commercial navigation on the river is unimportant because the river is cut off from the sea and other means of transportation are more efficient in the region. Peace Palace Libray Drought Watch Campaign - map of the Colorado River system showing the fill levels of major reservoirs Dams on the Lower Colorado River - A look at all the Dams on the Colorado River from Las Vegas Nevada to Mexico Grand Canyon North Rim