The river's first diversion is here at its headwater. The Grand Ditch redirects water from the Never Summer Mountains, which would have flowed into the Colorado River, to instead flow across the divide through La Poudre Pass to irrigate farmland to the east.
About a mile (1.5km) downstream from its source, the Colorado River has carved its first canyon, the narrow, deep Little Yellowstone Canyon. It then flows through the broad Kawuneeche Valley, where it is joined by U.S. Highway 34, which will roughly parallel it to the town of Granby. It finally exits Rocky Mountain National Park, flowing into Shadow Mountain Lake and then into Lake Granby, which are portions of the Colorado-Big Thompson Project, a large trans-basin water storage and delivery project that diverts water from the Colorado River under the Front Range mountains to provide an agricultural and municipal water supply for the northern Front Range and plains of Colorado. The traditional breakdown of water usage for the river in the state is approximately 80 percent for agriculture and 10 percent for municipal and industrial consumption.[1]
Starting in Granby, the river is roughly paralleled by U.S. Highway 40 to the town of Kremmling, and by the tracks of the Union Pacific Railroad until about the Utah border, carrying the AmtrakCalifornia Zephyr passenger train. The canyons and valleys of the Upper Colorado River are among the scenic attractions for passengers on this rail route.
Just downstream from Granby, the Colorado is joined by the Fraser River and flows through Windy Gap Reservoir, where more water is diverted to the Front Range via the Windy Gap Project. At Hot Sulphur Springs the river flows through Byers Canyon and then is joined by the Williams Fork from the left and Muddy Creek from the right shortly thereafter. Just below Kremmling it is joined by the Blue River from the left before flowing through Gore Canyon, famous for its challenging rapids for the sport of whitewater rafting, and where it drops significantly until State Highway 131 crosses at the village of State Bridge, where the Piney River joins from the left. The Eagle River joins from the left in the town of Dotsero, from where Interstate 70 will parallel the Colorado almost until it enters Utah.
The Colorado then enters the Grand Valley, where its waters are used to irrigate over 40,000 acres (16,000ha) of agricultural land. Here it passes Grand Junction, the largest town on the upper Colorado, where it is joined by the Gunnison River, its largest tributary within Colorado and second largest overall. The Gunnison drains from the northern San Juan Mountains, Elk Mountains and Sawatch Range – which includes Colorado's highest peak, 14,440-foot (4,400m)Mount Elbert – and carves the Black Canyon of the Gunnison before joining the Colorado. In the Grand Valley the Colorado becomes a meandering river in contrast to the steep mountain canyons above Grand Junction. It ranges from 200 to 1,200ft (60 to 370m) wide and from 6 to 30ft (2 to 9m) in depth with occasional deeper areas.
From there the Colorado turns northwest, past Fruita and entering Ruby Canyon as it approaches the Colorado Plateau. It turns southwest once again just before entering Utah.
Utah
Colorado River at Moab, UtahConfluence of Green (above) and Colorado Rivers in Canyonlands National Park
In Utah the Colorado enters the high desert canyon country of the Colorado Plateau, flowing swiftly southwest through Westwater Canyon. Near Dewey it picks up the Dolores River, which together with its tributary the San Miguel drains the western slope of the San Juan Mountains. It then passes the Fisher Towers and forms part of the southern border of Arches National Park before entering the Moab Valley at Moab. Just below Moab it carves through a 1,000-foot (300m) deep mountain pass known as "The Portal".
The Colorado then passes by Dead Horse Point State Park before entering the backcountry of Canyonlands National Park where it is joined from the north by the Green River, its biggest tributary. The Green, flowing from the Wind River Range of western Wyoming, drains 48,000 square miles (120,000km2) in southwest Wyoming, northeast Utah and northwest Colorado. It is much longer than the Colorado above their confluence and carries a larger load of silt, though the Colorado has a slightly greater flow. Before an act of Congress changed the name in 1921 this confluence marked the official beginning of the Colorado River proper. The approximately 350 miles (560km) of the Colorado above the confluence of the Green, including the entire section within Colorado, was known as the Grand River.[2][3][4]
Below the Green River the Colorado flows through Cataract Canyon, which contains some of its most difficult rapids. At Hite the Hite Crossing Bridge – the only bridge over the Colorado for nearly 300 miles (480km) – carries Utah State Route 95 over the river. Below here the Colorado is joined by the Dirty Devil River and begins to widen into Lake Powell, the giant reservoir formed by Glen Canyon Dam185 miles (298km) downstream. Lake Powell, a popular houseboating destination, is surrounded by the Glen Canyon National Recreation Area and receives over 2 million visitors each year despite its remote location. Before the dam was completed in 1966 the Colorado flowed through Glen Canyon, a sandstone gorge known for its colorful and intricately sculpted rock formations.
Aerial of Lake Powell
The Escalante River, a desert stream which runs through the sinuous slot canyons of Grand Staircase–Escalante National Monument, joins about two-thirds of the way down Lake Powell. The San Juan River, which carries runoff from the southern slopes of the San Juan Mountains and the Four Corners region in Colorado and New Mexico, joins several miles further downstream; it forms an arm of the lake nearly 70 miles (110km) long. Although the San Juan contributes only about one-tenth of the Colorado River flow, it is extremely muddy, contributing as much as 40percent of the total sediment load. The area around the confluence is dominated geographically by Navajo Mountain which rises over a mile (1.6km) above the surrounding landscape, which is part of the Navajo Nation. Rainbow Bridge, one of the highest natural bridges in the world, is located at the tip of an arm of Lake Powell at the foot of Navajo Mountain.
Arizona
Glen Canyon Dam, which creates Lake Powell, is situated in the town of Page in northern Arizona only about 15 miles (24km) by river from the Utah border. The 710-foot (220m) dam impounds the Colorado primarily for hydroelectricity generation. In front of the dam the Glen Canyon Bridge carries U.S. Route 89 over the Colorado River. Below here the Colorado flows through the last 16 miles (26km) of Glen Canyon, passing the scenic Horseshoe Bend, before emerging briefly from its canyons at Lee's Ferry, where it is joined by the warm, shallow, muddy Paria River. Historically a ford used by Native Americans, explorers and settlers, Lee's Ferry serves as the dividing point between the Upper and Lower Colorado River Basins, which were each allocated one-half of the Colorado River flow in the Colorado River Compact of 1922.
Navajo Bridges over Marble Canyon, just downstream of Lee's Ferry
Below Lee's Ferry the Colorado begins to trend more south than southwest, through the vertical-walled Marble Canyon which is crossed by the twin Navajo Bridges as it enters Grand Canyon National Park. At the southern end of Marble Canyon, the river is joined by another tributary, the capricious Little Colorado River, which drains the Painted Desert region of northeast Arizona and western New Mexico. Although normally a calm and clear spring-fed stream, it can rise dramatically following monsoon storms over the Colorado Plateau.
Colorado River view at Toroweap, with Lava Falls in the center
Then the river then turns abruptly west directly across the folds and fault line of the plateau, through the Upper and Lower Granite Gorges of Grand Canyon, which is 217 miles (349km) long and from 4 to 20 miles (6.4 to 32.2km) between the upper cliffs. The walls, 4,000 to 6,000ft (1,200 to 1,800m) high, drop in successive escarpments of 500 to 1,600ft (150 to 490m), banded in splendid colors toward the narrow gorge of the present river. The river itself is a nearly uninterrupted series of violent rapids separated by calm, short pools. Deep inside the canyon it is joined from the north by Kanab Creek, which flows from southern Utah, and then from the south by Havasu Creek, known for the waterfalls it forms on the Havasupai Reservation. Further downstream it passes the Uinkaret volcanic field, where basalt eruptions millions of years ago formed huge lava dams across the Colorado. Although the dams have mostly been erased by erosion, a small portion remains as Lava Falls, generally considered the most difficult and dangerous rapids for boaters on the Colorado River.
The Colorado then swings sharply south and turns northwest north of Peach Springs, emerging from the Grand Canyon at the Grand Wash Cliffs, where it widens into the upper reaches of Lake Mead. The area also marks the general boundary between the Colorado Plateau and the Mojave Desert. Shortly west of that point it begins to form the border of Nevada to the north/west and Arizona to the south/east.
Lake Mead, formed by the 726-foot (221m)-high Hoover Dam about 30 miles (48km) southeast of Las Vegas, Nevada, is the largest reservoir in the United States with a full capacity of 28,945,000 acre-feet (35.703km3) and a water surface of nearly 250 square miles (650km2). However, the lake has not been full for many years due to a combination of drought and increased water usage by Colorado River Basin states. Situated in the Lake Mead National Recreation Area, Lake Mead is a popular recreation site – visited by almost 8 million people a year – and a critical source of water for the Las Vegas metropolitan area, Central Arizona and Southern California.
The lake is divided into three main bodies – from upstream to downstream they are the Gregg, Virgin and Boulder Basins, of which Virgin Basin is the largest. Virgin Canyon connects Gregg Basin to Virgin Basin, and the much narrower Boulder Canyon links Virgin Basin to Boulder Basin. Overton Arm, stretching northward for more than 40 miles (64km) from Virgin Basin, is fed by the Virgin River – which flows from Utah's Zion National Park – and the Muddy River, which drains a large area of the southern Nevada desert. Before Lake Mead was filled in the 1930s the Muddy River flowed into the Virgin River, which ran southward through what is now Overton Arm to join the Colorado River near the now-ghost town of St. Thomas, Nevada.
At Hoover Dam, the Colorado turns due south through Black Canyon, a direction it will follow for the remainder of its course to the Gulf of California. It passes under the Mike O'Callaghan–Pat Tillman Memorial Bridge (Hoover Dam Bypass), the highest concrete arch bridge in the world, carrying U.S. Route 93 at a height of 900 feet (270m) above the Colorado River.
The Colorado forms the border of California to the west and Arizona to the east for most of its course through the desert Lower Colorado River Valley (LCRV), where its character changes significantly from fast-flowing whitewater to a low gradient braided stream with a wide floodplain. Here, the Colorado River ranges in width from 700 to 2,500ft (200 to 800m) and from 8 to 100ft (2 to 30m) in depth. It becomes a losing stream, with a gradual reduction in volume both due to evaporation in the hot desert climate and massive diversions for irrigation, urban areas, industry and thermo-electric power generation. The average flow rate of 14,180 cubic feet per second (402m3/s) at Davis Dam[5] diminishes to just 2,060 cubic feet per second (58m3/s) at the Mexican border.[6]
Colorado River, Blythe and farmlands in the Palo Verde ValleyImperial Dam and the All-American Canal
The river flows through the Parker Valley, much of which belongs to the Colorado River Indian Reservation, and then the Palo Verde Valley, where it is crossed by Interstate 10 near Blythe, California. The small Headgate Rock Dam removes water for irrigation in the Parker Valley and the Palo Verde Dam provides water to the Palo Verde Valley. The river then flows through a canyon in the Trigo Mountains, where the Cibola and Imperial National Wildlife Refuge encompass the wetland areas formed above Imperial Dam, which filled with silt shortly upon its completion in the 1930s. Most of the Colorado's remaining flow is removed for irrigation here. The Gila Gravity Main Canal provides water for the Gila Valley in Arizona. The All-American Canal, which runs west to the Imperial Valley of California, is the largest irrigation canal in the world, capable of carrying 26,155 cubic feet per second (740.6m3/s) – the entire natural flow of the Colorado prior to damming. The canal supplies more than half a million acres (2000km2) which due to its mild climate grows most of the winter produce in the United States.
Below Imperial Dam the remnants of the Colorado river lessen in gradient and in its lower course flows through the Colorado Desert in a broad sedimentary plain upriver from Yuma, Arizona, where it is joined by the Gila River. The Gila was once one of the Colorado's largest tributaries, draining a huge swath of Arizona and western New Mexico. Today, most of its flow is diverted for irrigation and municipal use in the Phoenix area which leave the river below Gila Bend dry in most years. However, in certain seasons of extreme precipitation, such as the floods of January 1993, the Gila can carry massive amounts of water far exceeding the natural flow of the Colorado 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 natural dike cuts off the flow of the river to the remarkable low area in southern California known as the Salton Sink in the Coachella Valley, and the Imperial Valley. The Salton Sink and its Salton Sea are located below sea level; therefore, the descent from the river near Yuma is very much greater than the descent from Yuma to the Gulf of California. This geographical peculiarity is the result of the Colorado River Delta, formed over millions of years by over 10,000 cubic miles (42,000km3) of rock and sand eroded from the Grand Canyon and other canyons along the river's course. The delta eventually split the Gulf of California in two; the northern part in present-day California, cut off from the sea, eventually evaporated, creating a "sink" more than 200 feet (61m) below sea level.
In 1905, an attempt to establish an irrigation canal from the Colorado River to the Imperial Valley resulted in disaster as the Colorado escaped its channel into a pair of dry arroyos, the New River and Alamo River. For the next two years the Colorado flowed uncontrollably into the Salton Sink flooding farmland and creating the Salton Sea, which still exists today as the largest inland body of water in California. The river was finally diverted back to its present course in 1907. Geological evidence suggests that this has happened naturally many times in the past, filling Lake Cahuilla, with the floodwaters slowly evaporating over spans of decades before being re-flooded by the Colorado.
Mexico
The Colorado River meets the Mexico–United States border at the Northern International Boundary (NIB), where the Morelos Dam diverts nearly the entire remaining flow into the Reforma Canal and the Tijuana Aqueduct. Most of this water is used for irrigation in the Mexicali Valley, one of Mexico's most fertile agricultural regions.[7] Below the Morelos Dam the Colorado forms the international border for a short distance, between Baja California and Arizona, before reaching the Southern International Boundary at San Luis Rio Colorado, where it crosses entirely into Mexico.
Colorado River as it exits the United States into Mexico beneath the San Luis Colorado-Colonia Miguel Aléman Bridge (September 09)
For the remainder of its course to the Gulf, the river forms the boundary between Baja California (west) and Sonora (east). "River", however, is a misnomer as the Colorado is dry or small stream most of the year, due to its flow being almost completely exhausted by upstream diversions. The river bed will occasionally contain water, though, due either to monsoon storms over the Gila River Basin, or more rarely due to a particularly heavy snowmelt in the Rocky Mountains. Since the filling of Lake Powell in the 1960s the latter has only occurred four times – the unusually wet years of 1983 through 1986. In May 2014, an agreement between the US and Mexican governments known as Minute 319 enabled the intentional release of water into the Colorado River bed for the first time, with the goal of revitalizing the ecosystem of the Colorado River Delta.
Prior to the mid 20th century, the 3,000-square-mile (7,800km2) Colorado River Delta provided a rich estuarine marshland; while today it is now essentially desiccated, the river is still an important salt-water estuary resource. The estuary of the Colorado River was subjected to a major tidal bore that has almost disappeared with the drastic reduction in the freshwater flow following the irrigation diversions of the Colorado River, and to a lesser extent because of some dredging of the estuary channel.[8] The first historical record of the tidal bore was that of the Croatian missionary in Spanish service Father Ferdinand Konščak on 18 July 1746. During spring tide conditions, the tidal bore formed in the estuary about Montague Island and propagated upstream. It was called locally 'El Burro' or 'burro'. Today the tidal bore is rarely seen although there are still some anecdotal observations.
The Colorado River is one of the principal rivers in the Southwestern United States and in northern Mexico. The 1,450-mile-long (2,330 km) river, the 5th longest in the United States, drains an expansive, arid watershed that encompasses parts of seven U.S. states and two Mexican states. The name Colorado derives from the Spanish language for "colored reddish" due to its heavy silt load. Starting in the central Rocky Mountains of Colorado, it flows generally southwest across the Colorado Plateau and through the Grand Canyon before reaching Lake Mead on the Arizona–Nevada border, where it turns south toward the international border. After entering Mexico, the Colorado approaches the mostly dry Colorado River Delta at the tip of the Gulf of California between Baja California and Sonora.
In the context of physical geography, the Intermontane Plateaus is one of eight physiographic regions of the contiguous United States. The region consists mostly of plateaus and mountain ranges lying between the Rocky Mountains on the east and the Cascade and Sierra Nevada Mountains on the west. It is subdivided into three physiographic provinces: the Columbia Plateau in the north, the Basin and Range Province in the central and southwestern portions, and the Colorado Plateau in the southeast. In turn, each of these provinces are each subdivided into a number of physiographic sections.
Glen Canyon Dam is a concrete arch-gravity dam in the southwestern United States, located on the Colorado River in northern Arizona, near the city of Page. The 710-foot-high (220 m) dam was built by the Bureau of Reclamation (USBR) from 1956 to 1966 and forms Lake Powell, one of the largest man-made reservoirs in the U.S. with a capacity of more than 25 million acre-feet (31 km3). The dam is named for Glen Canyon, a series of deep sandstone gorges now flooded by the reservoir; Lake Powell is named for John Wesley Powell, who in 1869 led the first expedition to traverse the Colorado River's Grand Canyon by boat.
Lake Powell is an artificial reservoir on the Colorado River in Utah and Arizona, United States. It is a major vacation destination visited by approximately two million people every year. It is the second largest artificial reservoir by maximum water capacity in the United States behind Lake Mead, storing 24,322,000 acre-feet (3.0001×1010 m3) of water when full. However, Lake Mead has fallen below Lake Powell in size several times during the 21st century in terms of volume of water, depth and surface area.
The Little Colorado River is a tributary of the Colorado River in the U.S. state of Arizona, providing the principal drainage from the Painted Desert region. Together with its major tributary, the Puerco River, it drains an area of about 26,500 square miles (69,000 km2) in eastern Arizona and western New Mexico. Although it stretches almost 340 miles (550 km), only the headwaters and the lowermost reaches flow year-round. Between St. Johns and Cameron, most of the river is a wide, braided wash, only containing water after heavy snowmelt or flash flooding.
The Merced River, in the central part of the U.S. state of California, is a 145-mile (233 km)-long tributary of the San Joaquin River flowing from the Sierra Nevada into the San Joaquin Valley. It is most well known for its swift and steep course through the southern part of Yosemite National Park, where it is the primary watercourse flowing through Yosemite Valley. The river's character changes dramatically once it reaches the plains of the agricultural San Joaquin Valley, where it becomes a slow-moving meandering stream.
The Green River, located in the western United States, is the chief tributary of the Colorado River. The watershed of the river, known as the Green River Basin, covers parts of the U.S. states of Wyoming, Utah, and Colorado. The Green River is 730 miles (1,170 km) long, beginning in the Wind River Mountains of Wyoming and flowing through Wyoming and Utah for most of its course, except for a short segment of 40 miles (64 km) in western Colorado. Much of the route traverses the arid Colorado Plateau, where the river has carved some of the most spectacular canyons in the United States. The Green is slightly smaller than Colorado when the two rivers merge but typically carries a larger load of silt. The average yearly mean flow of the river at Green River, Utah is 6,121 cubic feet (173.3 m3) per second.
The Gila River is a 649-mile-long (1,044 km) tributary of the Colorado River flowing through New Mexico and Arizona in the United States. The river drains an arid watershed of nearly 60,000 square miles (160,000 km2) that lies mostly within the U.S., but also extends into northern Sonora, Mexico.
The San Juan River is a major tributary of the Colorado River in the Southwestern United States, providing the chief drainage for the Four Corners region of Colorado, New Mexico, Utah, and Arizona. Originating as snowmelt in the San Juan Mountains of Colorado, it flows 383 miles (616 km) through the deserts of northern New Mexico and southeastern Utah to join the Colorado River at Glen Canyon.
The Virgin River is a tributary of the Colorado River in the U.S. states of Utah, Nevada, and Arizona. The river is about 162 miles (261 km) long. It was designated Utah's first wild and scenic river in 2009, during the centennial celebration of Zion National Park.
The Dolores River is a tributary of the Colorado River, approximately 241 miles (388 km) long, in the U.S. states of Colorado and Utah. The river drains a rugged and arid region of the Colorado Plateau west of the San Juan Mountains. Its name derives from the Spanish El Rio de Nuestra Señora de Dolores, River of Our Lady of Sorrows. The river was explored and possibly named by Juan Maria Antonio Rivera during a 1765 expedition from Santa Fe.
The Salt River is a river in Gila and Maricopa counties in Arizona, United States, that is the largest tributary of the Gila River. The river is about 200 miles (320 km) long. Its drainage basin covers about 13,700 square miles (35,000 km2). The longest of the Salt River's many tributaries is the 195-mile (314 km) Verde River. The Salt's headwaters tributaries, the Black River and East Fork, increase the river's total length to about 300 miles (480 km). The name Salt River comes from the river's course over large salt deposits shortly after the merging of the White and Black Rivers.
Lees Ferry is a site on the Colorado River in Coconino County, Arizona in the United States, about 7.5 miles (12.1 km) southwest of Page and 9 miles (14 km) south of the Utah–Arizona state line.
The Sevier River is a 400-mile (640 km)-long river in the Great Basin of southwestern Utah in the United States. Originating west of Bryce Canyon National Park, the river flows north through a chain of high farming valleys and steep canyons along the west side of the Sevier Plateau before turning southwest and terminating in the endorheic basin of Sevier Lake in the Sevier Desert. It is used extensively for irrigation along its course, with the consequence that Sevier Lake is usually dry.
The Yuba River is a tributary of the Feather River in the Sierra Nevada and eastern Sacramento Valley, in the U.S. state of California. The main stem of the river is about 40 miles (64 km) long, and its headwaters are split into three major forks. The Yuba River proper is formed at the North Yuba and Middle Yuba rivers' confluence, with the South Yuba joining a short distance downstream. Measured to the head of the North Yuba River, the Yuba River is just over 100 miles (160 km) long.
The humpback chub is a federally protected fish that lived originally in fast waters of the Colorado River system in the United States. This species takes its name from the prominent hump between the head and dorsal fin, which is thought to direct the flow of water over the body and help maintain body position in the swift currents of the Colorado river. The body is almost entirely scaleless, retaining only about 80 mid-lateral scales along the lateral line. The fish is very streamlined, with a thin caudal peduncle and a deeply forked tail. The back is a light olive gray, the sides silver, and the belly white. The dorsal fin usually has nine rays, and the anal fin 10 or more. Maximum recorded length is 38 cm.
Arizona is a landlocked state situated in the southwestern region of the United States of America. It has a vast and diverse geography famous for its deep canyons, high- and low-elevation deserts, numerous natural rock formations, and volcanic mountain ranges. Arizona shares land borders with Utah to the north, the Mexican state of Sonora to the south, New Mexico to the east, and Nevada to the northwest, as well as water borders with California and the Mexican state of Baja California to the southwest along the Colorado River. Arizona is also one of the Four Corners states and is diagonally adjacent to Colorado.
The Colorado River Storage Project is a United States Bureau of Reclamation project designed to oversee the development of the upper basin of the Colorado River. The project provides hydroelectric power, flood control and water storage for participating states along the upper portion of the Colorado River and its major tributaries.
Bridge Canyon Dam, also called Hualapai Dam, was a proposed dam in the lower Grand Canyon of the Colorado River, in northern Arizona in the United States. It would have been located near Bridge Canyon Rapids in an extremely rugged and isolated portion of the canyon, 235 miles (378 km) downstream of Lees Ferry and at the uppermost end of Lake Mead.
The Marble Canyon Dam, also known as the Redwall Dam, was a proposed dam on the Colorado River in Arizona. The dam was intended to impound a relatively small reservoir in the central portion of Marble Canyon to develop hydroelectric power. Plans centered on two sites between miles 30 and 40 in the canyon. At one point a 38-mile (61 km) tunnel was proposed to a site just outside Grand Canyon National Park to develop the site's full power generation potential, reducing the Colorado River to a trickle through the park.
References
↑ Spivak, Daniel S. “The Colorado River Drought Contingency Plan: An Opportunity for Exploring Demand Management Through Integrated and Collaborative Water Planning.” Natural Resources Journal, vol. 61, no. 2, 2021, pp. 173–204. JSTOR website Retrieved 5 June 2023.
↑ Chanson, H. (2009). Environmental, Ecological and Cultural Impacts of Tidal Bores, Benaks, Bonos and Burros. Proceedings of the International Workshop on Environmental Hydraulics IWEH09, Theoretical, Experimental and Computational Solutions, Valencia, Spain, 29–30 October, P.A. LOPEZ-JIMENEZ, V.S. FUERTES-MIQUEL, P.L. IGLESIAS-REY, G. LOPEZ-PATINO, F.J. MARTINEZ-SOLANO, and G. PALAU-SALVADOR Editors, Invited keynote lecture, 20 pages (CD-ROM).
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