(Redirected from Colorado River (US)):''This article is about the Colorado River which flows through the Grand Canyon. For other rivers named Colorado, see
Colorado River (disambiguation).
The Colorado River from the bottom of Marble Canyon, in the Upper Grand Canyon
Colorado River in the Grand Canyon from Desert View
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.
The Colorado River drains 242,900 sq mi (629,100 km²). Total flows of the river range from 4000 cubic feet per second (570 m³/s) in droughts to 1,000,000 ft³/s (28,000 m³/s) in severe floods. With the construction of massive power dams on the lower course of the river, floods of over 70,000 ft³/s (2000 m³/s) are rare. The mean flow of the total river before diversion is 22,000 ft³/s. Historically the flow was much higher before water usage began in the basin.
Course
The Colorado River's source is
La Poudre Pass Lake, located high in
Rocky Mountain National Park, just west of the
Continental Divide. After leaving Rocky Mountain National Park the river flows through the Kawuneeche Valley and is then dammed to create Grand Lake and Shadow Mountain Reservoir. The river then flows into Lake Granby, another reservoir, and finally begins its journey to the
Gulf of California where US Highway 40 roughly parallels the river to the town of
Kremmling, where it enters Gore Canyon. About a hundred miles later it meets the Eagle River in the town of
Dotsero, Colorado and where
I-70 parallels the river through
Glenwood Canyon. The river then passes through the city of
Glenwood Springs where it is joined by the swift flowing Roaring Fork River. West of Glenwood Springs, the Colorado runs through the
Grand Valley and is joined by the
Gunnison River in
Grand Junction. From there it flows westward to the
Utah border and
Westwater Canyon. The Colorado here ranges from 200 to 1200 feet wide (60 to 370 m) and from 6 to 30 feet in depth (2 to 9 m) with occasional deeper areas.
The Colorado in James M. Robb Colorado River State Park as the Morning Sun rises
Once inside of 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. The river then flows into
Lake Powell, formed by the
Glen Canyon Dam. Below the dam, water released from the bottom of Lake Powell makes the river clear, clean, and cold. 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. Here, the Colorado ranges from 300 to 2000 feet in width (90 to 610 m) and 9 to 130 feet in depth (3 to 40 m).
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 across 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. The walls, 4000 to 6000 feet high (1200 to 1800 m), drop in successive escarpments of 500 to 1600 feet (150 to 490 m), banded in splendid colours toward the narrow gorge of the present river.
Below the confluence of the
Virgin River of
Nevada the Colorado abruptly turns southward.
Hoover Dam, built during the Great Depression, forms
Lake Mead, a popular recreation site as well as the supplier of most of the water for the city of
Las Vegas. From Hoover Dam, the river flows south and forms part of the boundary between
Arizona and
Nevada and between Arizona and
California. Along the California-Arizona reach of the river, four additional dams are operated to divert water for agricultural irrigation and for recreation.
Lake Mohave, formed by
Davis Dam, lies in the southern portion of the
Lake Mead National Recreation Area.
Lake Havasu, formed by
Parker Dam, provides recreation as well as the home of the retired
New London Bridge. The two remaining dams supply irrigation water: 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 channel through much of this region is bedded in a dike-like embankment lying above the floodplain over which the escaping water spills in time of flood. This dike cuts off the flow of the river to the remarkable low area in southern California known as the
Salton Sink,
Coachella Valley, or
Imperial Valley. The Salton Sink is located below sea level; therefore, the descent from the river near Yuma is very much greater than the descent from Yuma to the gulf.
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. Prior to the mid
20th century, the
Colorado River Delta provided a rich estuarine marshland that is now essentially desiccated, but nonetheless is an important ecological resource.
Elevation summary
Approximate heights above sea level at several key locations:
Note that the significant difference between the present height of the rim 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, it would have followed some other path around the upheaval). Estimates for the beginning of this erosion/upheaval process range from 5 to 70 million years ago.
Engineering
Glen Canyon Dam and Lake Powell
In the autumn of 1904, the river's waters escaped into a diversion canal a few miles below Yuma, Arizona, creating the
New River and
Alamo River. The rivers re-created in California a great inland sea in an area that it had frequently inundated before, for example, in 1884 and 1891, when it had for a time practically abandoned its former course through Mexican territory to the
Sea of Cortez. But it was effectively dammed in the early part of 1907 and returned to its normal course, from which, however, there was still much leakage to the
Salton Sea. In July 1907, the permanent dam was completed. From the Black Canyon towards the sea the Colorado normally flows through a desert-like basin.
From the Hoover Dam
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. Other dams include
Hoover Dam,
Parker Dam,
Davis Dam,
Palo Verde Diversion Dam, and
Imperial Dam. Since the completion of the dams, the majority of the river in normal hydrologic years is diverted for agricultural and municipal water supply. The Colorado's last drops evaporate in the
Sonoran Desert, miles before the river reaches the Gulf of California. Almost 90% of all water diverted from the river is for irrigation purposes. The
All-American Canal is the largest irrigation canal in the world and carries a volume of water from 15,000 to 30,000 ft³/s (420 to 850 m³/s), making it larger in volume than
New York's Hudson River. The canal's waters are used to irrigate the parched but fertile Imperial Valley, where several years can pass between measurable rainfalls.
Hydrology transport models are used to assess management of the river's flow and water quality.
Hoover Dam (originally ''Boulder Dam'', and the first dam of its type) was completed in 1936. Its impoundment of the river in the
Mojave Desert creates
Lake Mead, which provides water for irrigation and the generation of
hydroelectric power.
Several cities such as
Los Angeles,
Las Vegas,
San Diego,
Phoenix, and
Tucson have aqueducts leading all the way back to the Colorado River. One such aqueduct is the
Central Arizona Project ("CAP") canal, which was begun in the
1970s and finished in the
1990s. The canal begins at Parker Dam and runs all the way to Phoenix and then Tucson to supplement those cities' water needs.
The Colorado is navigable by moderate to large sized craft throughout most of its length. 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, making other means of transportation more efficient in the region. Before the railroads arrived, the Lower Colorado River from the Sea to near present day
Laughlin, Nevada was an important means of transportation via large steamers.
Wildlife
The Colorado River basin is home to fourteen native species of fish. Four are
endemic and
endangered: Colorado pikeminnow (formerly Colorado squawfish),
razorback sucker, bonytail chub, and humpback chub. The
Upper Colorado River Endangered Fish Recovery Program is a controversial effort by the
US Fish and Wildlife Service, in conjunction with the
Arizona Game and Fish Department, the
Colorado Division Of Wildlife, and the
Utah Department Of Wildlife to recover these endangered fish.
Moab, Utah uranium tailings
Main articles: Moab Tailings
Atlas Corporation operated a
uranium mine in the area of
Moab, Utah, just under three miles from downtown Moab. As a byproduct of mining activities, a ten-million-ton pile of radioactive
tailings exists. The pile is located about 700-800 feet from the Colorado River. Although no pollution has been detected, proximity of the material to the watershed has been a concern. The Senate has authorized the
US Department of Energy to budget $22.8 million in 2007 to begin the project of moving the uranium tailings further from the river. The plan is to move the pile 15-20 miles north and away from the river. The project is expected to be completed by 2017.
References
1. Largest Rivers in the United States, USGS; retrieved April 22, 2007.
See also
★
List of Colorado River rapids and features
★
Colorado River Delta
★
Colorado River Compact
External links
★
Federal Department of Energy site on uranium mine tailing site.
★
State of Utah site on uranium mine tailings.
★
Bibliography on Water Resources and International Law See 'Colorado River'. Peace Palace Libray
★
Drought Watch Campaign - map of the Colorado River system showing the fill levels of major reservoirs. Last updated April 2004.
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