Colorado
Colorado is a mapped river in the YearMaps hydrographic index. 2 dams stand on this watercourse and are written up below. River courses organise settlement, agriculture and frontier-making more durably than any political boundary, and this reach is indexed against the dams, lakes and cities within its catchment.
- Feature Class
- River
- Dams Recorded
- 2
- Coordinates
- 36.93°, -111.47°
About Colorado
The Colorado River (Spanish: Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and in northern Mexico. The 1,450-mile-long (2,330 km) river, the Fifth-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 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.
Known for its dramatic canyons, whitewater rapids, and eleven U.S. National Parks, the Colorado River and its tributaries are a vital source of water for 40 million people. An extensive system of dams, reservoirs, and aqueducts divert almost its entire flow for agricultural irrigation and urban water supply.
Encyclopedic summary adapted from Wikipedia: Colorado River (CC BY-SA 4.0).
Colorado in Depth
Course
The Colorado begins as many tributaries in Wyoming and Colorado, the largest being the Green River. The Colorado River itself starts in Rocky Mountain National Park then makes a short run south, then the river turns west below Grand Lake, the largest natural lake in Colorado state. For the first 250 miles (400 km) of its course, the Colorado carves its way through the mountainous Western Slope, a sparsely populated region defined by the portion of the state west of the Continental Divide. As it flows southwest, it gains strength from many small tributaries, as well as larger ones including the Blue, Eagle and Roaring Fork rivers.
History
Small numbers of Paleo-Indians of the Clovis and Folsom cultures inhabited the Colorado Plateau as early as 10,000 BCE, with populations beginning to increase in the Desert Archaic period (6000 BCE–0 CE). While most early inhabitants were hunter-gatherers, evidence of agriculture, masonry dwellings and petroglyphs begins with the Fremont culture period (0–1300 CE). The Ancient Puebloan culture, also known as Anasazi or Hisatsinom, were descended from the Desert Archaic culture and became established in the Four Corners region around 1000 CE.
While there is much evidence of ancient habitation along the Colorado River, including stone dwellings, petroglyphs and pottery in places such as Glen Canyon, the first major agriculture-based societies arose a significant distance from the river.
Ecology
The Colorado River and its tributaries often nourish extensive corridors of riparian growth as they traverse the arid desert regions of the watershed. Although riparian zones represent a relatively small proportion of the basin and have been affected by engineering projects and river diversion in many places, they have the greatest biodiversity of any habitat in the basin. The most prominent riparian zones along the river occur along the lower Colorado below Davis Dam, especially in the Colorado River Delta, where riparian areas support 358 species of birds despite the reduction in freshwater flow and invasive plants such as tamarisk (salt cedar). Reduction of the delta's size has also threatened animals such as jaguars and the vaquita porpoise, which is endemic to the gulf.
Geology
As recently as the Cretaceous period about 100 million years ago, much of western North America was still part of the Pacific Ocean. Tectonic forces from the collision of the Farallon Plate with the North American Plate pushed up the Rocky Mountains between 50 and 75 million years ago in a mountain-building episode known as the Laramide orogeny. The Colorado River first formed as a west-flowing stream draining the southwestern portion of the range, and the uplift also diverted the Green River, once a tributary of the Mississippi River, west towards the Colorado.
Sections adapted from Wikipedia: Colorado River (CC BY-SA 4.0).
Colorado: Key Facts
| Length | 2,334 km |
|---|---|
| Average discharge | 640 m³/s |
| Drainage basin | 637,137 km² |
| Source | La Poudre Pass |
| Mouth | Gulf of California |
| Drainage system | Colorado River drainage basin |
| Tributaries | Eagle River, Roaring Fork River, Gunnison River, Dolores River, Range Creek, San Juan River, Little Colorado River, Gila River |
Facts from Wikidata Q1265 (CC0).
Dams on the Colorado
2 dams on the Colorado, ordered by structural height, with their reservoirs and generating capacity.
| Dam | Height | Capacity | Completed |
|---|---|---|---|
| Hoover Dam | 221 m | 2,080 MW | 1936 |
| Glen Canyon Dam | 216 m | 1,320 MW | 1966 |
Hoover Dam
Concrete Arch-Gravity dam · Nevada / Arizona, USA
Hoover Dam is a concrete arch-gravity dam on the Colorado in Nevada / Arizona, USA, standing 221 m (725 ft) high and completed in 1936. It carries an installed hydroelectric capacity of 2,080 MW. The structure impounds Lake Mead, about 787 km² on the map.
The Hoover Dam is a concrete arch–gravity dam in the Black Canyon of the Colorado River, on the boundary between the U.S. states of Nevada and Arizona. Constructed between 1931 and 1936, during the Great Depression, it was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over 96 lives. Bills passed by Congress during its construction referred to it as Hoover Dam (after President Herbert Hoover), but the Roosevelt administration named it Boulder Dam. In 1947, Congress reinstated the name Hoover Dam.
Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water, and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium named Six Companies, Inc., which began construction in early 1931. Such a large concrete structure had never been built before, and some of the techniques used were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties.
Adapted from Wikipedia: Hoover Dam (CC BY-SA 4.0).
- Dam type
- Concrete Arch-Gravity
- Structural height
- 221 m (725 ft)
- Installed capacity
- 2,080 MW
- Impounded river
- Colorado
- Reservoir
- Lake Mead
- Location
- Nevada / Arizona, USA
- Year completed
- 1936
- Height rank
- #14 of 115 indexed
- Output rank
- #31 of 102 indexed
- Coordinates
- 36.0156°, -114.7378°
Notable: Iconic Art Deco depression-era marvel; created Lake Mead, the largest reservoir in the US by volume.
Among the 115 dams indexed in YearMaps, Hoover Dam ranks #14 by structural height, behind Jinping-I Dam (305 m). By installed generating capacity it ranks #31, behind Three Gorges Dam (22,500 MW).
Impounded reservoir: Lake Mead (787 km², impounded 1936).
Nearest cities: Las Vegas (49 km), Bullhead City (98 km), Kingman (111 km).
More about Hoover Dam
Background
As the United States developed the Southwest, the Colorado River was seen as a potential source of irrigation water. An initial attempt at diverting the river for irrigation purposes occurred in the late 1890s, when land speculator William Beatty built the Alamo Canal just north of the Mexican border; the canal dipped into Mexico before running to a desolate area Beatty named the Imperial Valley. Though water from the Alamo Canal allowed for the widespread settlement of the valley, the canal proved expensive to operate. After a catastrophic breach that caused the Colorado River to fill the Salton Sea, the Southern Pacific Railroad spent $3 million in 1906–07 to stabilize the waterway, an amount it hoped in vain that it would be reimbursed for by the federal government.
Construction
Soon after the dam was authorized, increasing numbers of unemployed people converged on southern Nevada. Las Vegas, then a small city of some 5,000, saw between 10,000 and 20,000 unemployed descend on it. A government camp was established for surveyors and other personnel near the dam site; this soon became surrounded by a squatters' camp. Known as McKeeversville, the camp was home to men hoping for work on the project, together with their families. Another camp, on the flats along the Colorado River, was officially called Williamsville, but was known to its inhabitants as "Ragtown". When construction began, Six Companies hired large numbers of workers, with more than 3,000 on the payroll by 1932 and with employment peaking at 5,251 in July 1934.
Operation
Excavation for the powerhouse was carried out simultaneously with the excavation for the dam foundation and abutments. The excavation of this U-shaped structure located at the downstream toe of the dam was completed in late 1933 with the first concrete placed in November 1933. Filling of Lake Mead began February 1, 1935, even before the last of the concrete was poured that May. The powerhouse was one of the projects uncompleted at the time of the formal dedication on September 30, 1935; a crew of 500 men remained to finish it and other structures. To make the powerhouse roof bombproof, it was constructed of layers of concrete, rock, and steel with a total thickness of about 3.5 feet (1.1 m), topped with layers of sand and tar.
Environmental impact
The changes in water flow and use caused by Hoover Dam's construction and operation have had a large impact on the Colorado River Delta. The construction of the dam has been implicated in causing the decline of this estuarine ecosystem. For six years after the construction of the dam, while Lake Mead filled, virtually no water reached the mouth of the river.
Sections adapted from Wikipedia: Hoover Dam (CC BY-SA 4.0).
Hoover Dam: Key Facts
| Crest length | 379 m |
|---|---|
| Officially opened | 1936 |
Facts from Wikidata Q172822 (CC0).
Glen Canyon Dam
Concrete Arch dam · Arizona, USA
Glen Canyon Dam is a concrete arch dam on the Colorado in Arizona, USA, standing 216 m (709 ft) high and completed in 1966. It carries an installed hydroelectric capacity of 1,320 MW. The structure impounds Lake Powell, about 841 km² on the map.
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. Glen Canyon and Lake Powell are managed by the Department of the Interior within Glen Canyon National Recreation Area.
A dam in Glen Canyon was studied as early as 1924, but these plans were initially dropped in favor of the Hoover Dam (completed in 1936) which was located in the Black Canyon. By the 1950s, due to rapid population growth in the seven U.S. and two Mexican states comprising the Colorado River Basin, the Bureau of Reclamation deemed the construction of additional reservoirs necessary.
Adapted from Wikipedia: Glen Canyon Dam (CC BY-SA 4.0).
- Dam type
- Concrete Arch
- Structural height
- 216 m (709 ft)
- Installed capacity
- 1,320 MW
- Impounded river
- Colorado
- Reservoir
- Lake Powell
- Location
- Arizona, USA
- Year completed
- 1966
- Height rank
- #15 of 115 indexed
- Output rank
- #44 of 102 indexed
- Coordinates
- 36.9369°, -111.4839°
Notable: Controls water allocation between the Upper and Lower Colorado River basins.
Among the 115 dams indexed in YearMaps, Glen Canyon Dam ranks #15 by structural height, behind Jinping-I Dam (305 m). By installed generating capacity it ranks #44, behind Three Gorges Dam (22,500 MW).
Impounded reservoir: Lake Powell (841 km², impounded 1966).
Nearest cities: Cedar City (162 km), St. George (187 km), Flagstaff (194 km).
More about Glen Canyon Dam
Background
The Colorado River is the single largest source of water in the southwestern United States and northwest Mexico; before massive dam projects tamed the river in the 20th century, its flow was far from dependable. Annual discharge from the Colorado River and its tributaries ranges from 4 to 22 million acre-feet (4.9 to 27.1 km3), and 10-year averages may fluctuate as much as 1 million acre-feet (1.2 km3). Flooding, and the river's enormous silt or sediment load, created problems for settlements in the Lower Colorado River Valley and navigation on the lower portion of the river. During droughts, there was too little water available for irrigation.
Later history
During the El Niño winter of 1982–1983, the Bureau of Reclamation predicted an average runoff for the Colorado River basin based on snowpack measurements in the Rocky Mountains. Snowfall during April and May was exceptionally heavy; this combined with a sudden rise in temperatures and unusual rainstorms in June to produce major flooding across the western United States. With Lake Powell nearly full, the USBR did not have enough time to draw down the reservoir to accommodate extra runoff. By mid-June, water was pouring into Lake Powell at over 120,000 cubic feet per second (3,400 m3/s). Even with the power plant and river outlet works running at full capacity, Lake Powell continued to rise to the point where the spillways had to be opened.
Construction
As early as 1947, the Bureau of Reclamation had begun investigating two potential sites, both located in the narrow lower reaches of Glen Canyon shortly upstream of Lee's Ferry. The site originally favored by the USBR was just 4 miles (6.4 km) upstream, but the final decision was to build the dam 16.5 miles (26.6 km) upstream because of stronger foundation rock and easier access to gravel deposits on Wahweap Creek. Because the dam site lay in a remote, rugged area of the Colorado Plateau – more than 30 miles (48 km) from the closest paved road, U.S. Route 89 – a new road had to be constructed, branching off from US 89 north of Flagstaff, Arizona, and running through the dam site to its terminus at Kanab, Utah.
Design
Glen Canyon's overall design was based on that of Hoover Dam – a massive concrete arch-gravity structure anchored in solid bedrock – with several significant changes. The engineers wanted the dam to rely predominantly on its arch shape to carry the tremendous pressure of the impounded water into the canyon walls instead of depending on the sheer weight of the structure to hold the reservoir back, as had been done at Hoover.
Sections adapted from Wikipedia: Glen Canyon Dam (CC BY-SA 4.0).
Glen Canyon Dam: Key Facts
| Crest length | 475 m |
|---|---|
| Officially opened | 1964 |
Facts from Wikidata Q1530724 (CC0).
Major River Dossiers
Hand-written studies of the great river systems of history.
Connected Reaches
Nearby watercourses in the same drainage network.
Water Bodies in the Catchment
Settlements Along the Reach
Hydraulic Infrastructure Nearby
Surrounding Terrain
Colorado: Quick Answers
- Where is Colorado?
- Colorado is located in United States and Mexico, at 36.9321° N, 111.4734° W.
- Are there dams on the Colorado?
- Yes. YearMaps records 2 dams on the Colorado: Hoover Dam, Glen Canyon Dam.
- What is the tallest dam on the Colorado?
- Hoover Dam is the tallest dam recorded on the Colorado, at 221 m (725 ft), completed in 1936.
- Which dam on the Colorado generates the most electricity?
- Hoover Dam has the largest installed hydroelectric capacity on the Colorado: 2,080 MW. Installed capacity is the maximum rated output, not the annual average.