Colorado River

Colorado River
Map of the Colorado Watershed
Origin	La Poudre Pass Lake
Mouth	Gulf of California
Basin countries	United States, Mexico
Length	2,330 km (1,450 mi)
Source elevation	~2700 m (~9000 ft)
Avg. discharge	620 m³/s (22,000 ft³/s)[1]
Basin area	629,100 km² (242,900 mi²)

Downstream view of the Colorado River at river mile 174 in the Grand Canyon

The Colorado River ('Aha Kwahwat in Mojave)^[2] 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 (113 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 (620 m³/s). Historically the flow was much higher before water usage began in the basin.

History

Early Records

The existence of the Colorado River was first noted in the records of written history in September, 1539, when Francisco de Ulloa sailed to the head of the Gulf of California and rowed a short distance upstream. ^[3] It was next seen by Hernando de Alarcon who in 1540 led the maritime contingent of Coronado's expedition. The plan was to meet the land based force and resupply them. Alarcon ascended the river about 85 Spanish miles to the limit of navigation near present day Yuma, Arizona. He waited for Coronado, but eventually despaired, cached some supplies and correspondence, left a note on a tree, and departed. Coronado's land forces never reached that location, but Melchior Diaz, on his third expedition, went to see if he could establish contact with Alarcon. By the time he reached the Colorado, however, Alarcon had already left. The Native Americans told him what they knew of Alarcon's presence and that he had left a cache of supplies. Diaz found the note and the supplies. Diaz named the river Rio del Tizon ("River of Embers" or "Firebrand River") based on a practice used by the natives for warming themselves.[2] Meanwhile, Coronado (who at the time was near Zuni, New Mexico) had learned from one of his scouting parties that the natives spoke of a large river to the west. He sent Garcia Lopez de Cardenas to lead a contingent of men to find this river. They did find it at what is now known as the Grand Canyon, becoming the first people of European background to see it. Their failed attempts at reaching the river led them to conclude that it would not be possible to be supplied via the Gulf of California and the river.

Colorado River in the Grand Canyon from Desert View

The following year, Francisco de Bolanos sailed to the mouth of the river on the Gulf of California. One of his pilots, Domingo del Castillo, prepared a map of the Mexican coast. He charted three rivers at the head of the gulf and named them Brazo de laguna p., Rio de buena Guia p., and Brazo de Mira flores p.. The last of these is the longest.^[4] Later references suggest that Brazo de Mira flores referred to what is now called the Gila River, and that Rio de buena Guia was his name for the Colorado. (It is interesting to note that in spite of these records, the error that California was an island persisted for more than a century, especially among European cartographers.)

The Colorado River from Laughlin

Comparisons of 17th, 18th, and early 19th Century maps reveal a parade of names being applied to the Colorado and its tributaries, as well as a variety of courses, as cartographers learned or made up the geography of the region. ^[5] On a map by Nicholas Sanson (1650) the R. del Tecon and the R. de Coral share a common mouth on the gulf. A number of maps show the Gila River (sometimes just the lower, sometimes the whole) as the Rio Grande de las Apostoles. A 1763 map by Emanuel Bowen equates the Apostles with the del Coral. A 1720 map by Fer Nicholas labels the main body of the Colorado as Rio del Tison, and a tributary of the Apostles/Gila as Rio Colorade. In 1703 Guillaume de L'Isle showed a Rio de buena esperanza as a major tributary of the Tison, but it is not clear if this tributary corresponds better with the Little Colorado or the San Juan. A map by Herman Moll (1720) charts the Tison and the Gila with separate mouths. Upriver from a tributary of the Tison that would appear to correspond with today's Virgin River, the name for the main channel is given as R. of Good Hope. On other maps Good Hope/Buena Esperanza are transferred to a tributary of the Gila. A map of 1757 gives the name of the main course as Rio Colorado de los Martyres. A map of 1781 by Jonathan Carver charts a major split in the river and labels the eastern branch Colorado and the western branch Martyres. A map from 1758 by Robert de Vaugondy, Didier applies the name Colorado to a river that reaches north to the headwaters of the Missouri, best corresponding to today's Green River. When Jedediah Smith first reached the lower Colorado in 1826, he first called it the Seedskeedee, as the headwaters of the Green River were known to the trappers, but also noted that the natives called it the Colorado.^[6]

It is not clear when or why the name "Colorado" first replaced "Tizon" (Tecon/Tison), which had been the most common name on maps since 1540. Among the maps in the Library of Congress, every use of "Colorado" (or Colorade) from 1720 and before is applied to a tributary of what is now the Gila River that seems best to correspond with todays Verde River.[3] The earliest map in that collection that replaces "Tizon" with "Colorado" is a map from 1743.[4]

The map that resulted from Escalante's expedition in 1776 labels the main channel as the Colorado up to the confluence of the Nabajoo and Zaguananas rivers. The associated information leads one to conclude that the Nabajoo corresponds to the San Juan and the Zaguananas to the Colorado from there to the Dolores River. On this map the Colorado above the Dolores is called the Rafael, and the Green River (named Buenaventura River) is erroneously diverted to the southwest and to what is now called Sevier Lake. Where Escalante's journal records his crossing of the San Rafael, he notes that the Native Americans knew this river as the Colorado. He also notes that the natives said this river had it source in a distant lake, but the lake is not charted on the resulting map. It is evident from a number of maps of the period that people were not aware of the distance between the Colorado's confluence with the Dolores and the western slopes of the Front Range. On a map from 1847 by John Disturnell, the Rafael is replaced with the Green River, while the upper Colorado (or more correctly, what would be called the Grand River) is not shown at all.

Grand River

Grand River is the name once applied to the Colorado River above its confluence with the Green River. The earliest appearance of this name on a map could be on the map by Henry Schenck Tanner (1836)[5]. The name there replaces the name of Rio Raphael, which appears on many earlier maps. The head of this branch of the Colorado is shown as at about the same latitude as Longs Peak in Colorado. There is nothing charted that corresponds to the Green River, nothing that corresponds with the course of the Dolores (even though some earlier maps did show the Dolores with reasonable accuracy), and the headwaters of both the Rio Grande ("Rio del Norte") and especially the Arkansas River are shown to reach to a higher latitude.

A map by David H. Burr (1839)[6] shows the "Colorado River of the West" flowing from the headwaters of the Green River to the Gulf of California, with the "Grand River" as a relatively minor tributary branching to the east as the third tributary upriver from the Nabajoo (San Juan). The Green River is not separately named. The headwaters of the Grand are depicted as being very close to the headwaters of the Rio Grande (which is labeled "Rio Bravo del Norte") as well as those of the Arkansas River. A textual note on the map indicates that little is known of this area. ^[7]

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,"^[8] the origin of several now orphaned names including Grand Lake, Grand Valley, Grand Junction, Grand County, Colorado, and Grand County, Utah. Colorado U.S. Representative Edward T. Taylor petitioned the Congressional Committee on Interstate and Foreign Commerce to rename the Grand River as the Colorado River. On July 25, 1921 the name change was made official in House Joint Resolution 460 of the 66th Congress, over the objections of representatives from Wyoming and Utah and the United States Geological Survey which noted that the drainage basin of the Green River was more than 70% more extensive than that of the Grand River^[9], although the Grand carried a slightly higher volume of water at its confluence with the Green.

Horseshoe Bend is a horseshoe-shaped meander of the Colorado River located near the town of Page, Arizona

Course

Prehistory

It is the opinion of some geologists that before the Gulf of California came into being some 7-8 million years ago, the Colorado River initially had its outlet somewhere along what is now the California coast. They believe that the massive Monterey Submarine Canyon under Monterey Bay along with the associated undersea sedimentary fan may be remnants of the Colorado's ancient outlet. ^[10] The canyon has moved north to its current location by the action of the San Andreas Fault and would have been approximately where Santa Barbara is located when both the San Andreas Fault and the Gulf of California came into being.

Today

The Colorado River's source is La Poudre Pass Lake, located high in Rocky Mountain National Park, just west of the Continental Divide. Below Rocky Mountain National Park, the river flows through the Kawuneeche Valley and then flows through Grand Lake, the largest natural body of water in Colorado, before being dammed to create Shadow Mountain Reservoir. The river then flows into Lake Granby, another reservoir, and finally begins its journey to the Gulf of California where U.S. Highway 40 roughly parallels the river to the town of Kremmling, where it enters Gore Canyon. Most of the river's tributaries within Colorado are small. However there are exceptions, such as the Gunnison and Roaring Fork Rivers, in which massive amounts of water flow. 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.

A remote stretch of the Colorado River from the Escalante Route in the Grand Canyon

The river turns southwest near Fruita, Colorado, and is joined by the Dolores River soon after entering Utah. It partially forms the southern border of Arches National Park near Moab, Utah, and 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 Colorado 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 175 to 700 feet in width (53 to 213 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.

Climate change

According to the Natural Resources Defense Council the Colorado River Basin, which stretches from Wyoming to Mexico, is at the center of hotter climate changes in the Western United States. Since the 1970s, rising temperatures have contributed to earlier snowmelts, and the basin has warmed more than any other area in the contiguous United States.

As a result, the volume of water in the basin is decreasing. The years 2000 to 2004 were the only five consecutive years in recorded history with water flow below average. Lake Powell, one of the basin's main reservoirs, is only 45 percent full.^[11]

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 otherwise 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. However, 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 Bernardino, 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 lower Colorado is navigable by moderate to large sized craft. 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. Most of the rest of the river, excluding the rapids in the canyons, is navigable by small to moderate sized river craft and power boats.

Colorado River

Moab uranium tailings

Main article: Moab Tailings

Atlas Mineral Corporation operated a uranium processing mill in the area of Moab, Utah, on the north bank of the Colorado River just under three miles from downtown Moab. As a byproduct of uranium processing activities, an estimated 16 million ton pile of chemically and radioactively hazardous tailings exists. The pile is located about 700-800 feet from the Colorado River. Although no contamination has been detected, the proximity of the material to the watershed has been a concern. The Senate has authorized the U.S. Department of Energy to budget $22.8 million in 2007 to begin the project of moving the uranium tailings farther from the river. The plan is to move the contaminated materials 30 miles north to a disposal site located at Cresent Junction, Utah. The project is expected to be completed by 2017.^[12]

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.

Fish Species

• Rainbow
• Largemouth Bass
• Striped Bass
• Crappie
• Sunfish
• Catfish (Channel)
• Carp
• Sturgeon
• Rainbow Trout
• Brook Trout

See also

• Colorado River Delta
• Colorado River Compact
• List of Colorado River rapids and features
• List of flora of the Lower Colorado River Valley

References

The Colorado River in James M. Robb Colorado River State Park as the Morning Sun rises

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.

External links

Wikimedia Commons has media related to:

Colorado River

• 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 Peace Palace Library
• Drought Watch Campaign - map of the Colorado River system showing the fill levels of major reservoirs. Last updated July 2004.
• Arizona Boating Locations Facilities Map
• Arizona Fishing Locations Map
• Where to Fish in Arizona Species Information

v • d • e Colorado River system Dams and aqueducts (see US Bureau of Reclamation) Shadow Mountain Dam • Granby Dam • Glen Canyon Dam • Hoover Dam • Davis Dam • Parker Dam • Palo Verde Diversion Dam • Imperial Dam • Laguna Dam • Morelos Dam • Colorado River Aqueduct • San Diego Aqueduct • Central Arizona Project • All-American Canal • Coachella Canal • Redwall Dam Canyons Byers Canyon • Gore Canyon • Red Gorge • Glenwood Canyon • De Beque Canyon • Horsethief Canyon • Ruby Canyon • Westwater Canyon • Cataract Canyon • Narrow Canyon • Glen Canyon • Grand Canyon (Marble Canyon • Granite Gorge • Middle Granite Gorge • Lower Granite Gorge) • Grand Wash Canyon • Iceberg Canyon • Virgin Canyon • Boulder Canyon • Black Canyon • Pyramid Canyon • Mohave Canyon Natural features Rocky Mountains • Colorado River Basin • Grand Lake • Sonoran Desert • Mojave Desert • Imperial Valley • Colorado Plateau • New River • Gulf of California/Sea of Cortez • Salton Sea Tributaries Blue River • Dirty Devil River • Dolores River • Escalante River • Eagle River • Fraser River • Gila River • Green River • Gunnison River • Kanab Creek • Little Colorado River • Paria River • Roaring Fork River • San Juan River • Virgin River• Williams Fork River Major reservoirs Fontenelle Reservoir • Flaming Gorge Reservoir • Taylor Park Reservoir • Navajo Reservoir • Lake Powell • Lake Mead • Lake Mohave • Lake Havasu Dependent states Arizona • California • Colorado • Nevada • New Mexico • Utah • Wyoming (See: Colorado River Compact) Designated areas Arches National Park • Canyonlands National Park • Colorado National Monument • Dead Horse Point State Park • Glen Canyon National Recreation Area • Grand Canyon National Park • Lake Mead National Recreation Area • Rocky Mountain National Park

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