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 Imperial 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 would be reimbursed by the federal government.
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Hoover Dam
Hoover Dam | Search for resources
An initial attempt at diverting the Colorado 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. Yes Yes, the Colorado River was seen as a potential source of irrigation water - initial attempt at diverting the river for irrigation purposes occurred when land speculator William Beatty built the Alamo Canal. Yes, William Beatty.
who was president when the hoover dam was built
user
Franklin D. Roosevelt.
assistant
where is this dam located?
user
Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona.
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did anyone try to find resources on this dam?
user
The Hoover Dam is a massive concrete arch-gravity dam, constructed in the Black Canyon of the Colorado River, on the border between the US states of Arizona and Nevada between 1931 and 1936 during the Great Depression. In 1928, Congress authorized the project to build a dam that would control floods, provide irrigation water and produce hydroelectric power. The winning bid to build the dam was submitted by a consortium called Six Companies, Inc. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and the lack of facilities near the site also presented difficulties.
Dam | Large dams
Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and 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 one hundred lives. Originally known as Boulder Dam from 1933, it was officially renamed Hoover Dam for President Herbert Hoover by a joint resolution of Congress in 1947. 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.
Hoover Dam | Introduction
In the following years, the Bureau of Reclamation (BOR), known as the Reclamation Service at the time, also considered the Lower Colorado as the site for a dam. Service chief Arthur Powell Davis proposed using dynamite to collapse the walls of Boulder Canyon, north of the eventual dam site, into the river. The river would carry off the smaller pieces of debris, and a dam would be built incorporating the remaining rubble. In 1922, after considering it for several years, the Reclamation Service finally rejected the proposal, citing doubts about the unproven technique and questions as to whether it would, in fact, save money.
Hoover Dam | Search for resources
The dam is located near Boulder City, Nevada, a municipality originally constructed for workers on the construction project, about southeast of Las Vegas, Nevada. The dam's generators provide power for public and private utilities in Nevada, Arizona, and California. Hoover Dam is a major tourist attraction; nearly a million people tour the dam each year. The heavily traveled U.S. Route 93 (US 93) ran along the dam's crest until October 2010, when the Hoover Dam Bypass opened.
Hoover Dam | Introduction
The Black Canyon of the Colorado is the canyon on the Colorado River where Hoover Dam was built. The canyon is located on the Colorado River at the state line between Nevada and Arizona. The western wall of the gorge is in the El Dorado Mountains, and the eastern wall is in the Black Mountains of Arizona. The canyon formed about 15 million years ago during the Miocene Basin and Range uplift. Black Canyon gets its name from the black volcanic rocks that are found throughout the area. Just south of the Hoover Dam on the Nevada side of the canyon is the Sauna Cave.
Black Canyon of the Colorado | Introduction
Hoover Dam is a dam on the Colorado River bordering Nevada and Arizona, US. Hoover Dam or Hooverdam may also refer to:
Hoover Dam (disambiguation) | Introduction
Even after the waterway was stabilized, it proved unsatisfactory because of constant disputes with landowners on the Mexican side of the border. As the technology of electric power transmission improved, the Lower Colorado was considered for its hydroelectric-power potential. In 1902, the Edison Electric Company of Los Angeles surveyed the river in the hope of building a rock dam which could generate . However, at the time, the limit of transmission of electric power was , and there were few customers (mostly mines) within that limit. Edison allowed land options it held on the river to lapse—including an option for what became the site of Hoover Dam.
Hoover Dam | Search for resources
Excessive water pressure destroys most of the dams on the Colorado River. The Hoover Dam still survives. Over 300 miles behind it, lies the Glen Canyon Dam. In spring, rising temperatures trigger surging floodwater from melting snow and ice that races towards the dam. It reaches the Glen Canyon Dam, the spillways let some of the water out, but the tunnels built into the dam fill with high pressure bubbles that cause high pressure explosions and eat through the dam. Concrete ramps once prevented this, but now they have rusted into wrecks combined with water seeping through the cracks causing erosion.
Aftermath: Population Zero | (200 years A.H.)
The feasibility of Marble Canyon Dam was first explored in the 1920s by the United States Geological Survey, which designated sites for "an unbroken string of [hydroelectric] dams from the mountains of Colorado and Wyoming to the last canyons of the Colorado River along the California/Arizona border". Although the Bureau of Reclamation expressed interest at this time in developing hydroelectric generation at the Marble site, these plans were postponed in favor of building the Hoover Dam, which would provide a much greater storage capacity for irrigation and flood control. However, once Hoover was completed the Bureau once again set its sights on the Grand Canyon, which has the greatest hydroelectric potential of any canyon in the American Southwest.
Marble Canyon Dam | Exploration
Glen Canyon Dam is a concrete arch-gravity dam on the Colorado River in northern Arizona, United States, near the town of Page. The high dam was built by the U.S. 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 . 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's Grand Canyon by boat. 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.
Glen Canyon Dam | Introduction
One potential site at Boulder Canyon was bisected by a geologic fault; two others were so narrow there was no space for a construction camp at the bottom of the canyon or for a spillway. The Service investigated Black Canyon and found it ideal; a railway could be laid from the railhead in Las Vegas to the top of the dam site. Despite the site change, the dam project was referred to as the "Boulder Canyon Project". With little guidance on water allocation from the Supreme Court, proponents of the dam feared endless litigation. Delph Carpenter, a Colorado attorney, proposed that the seven states which fell within the river's basin (California, Nevada, Arizona, Utah, New Mexico, Colorado and Wyoming) form an interstate compact, with the approval of Congress.
Hoover Dam | Planning and agreements
This was done by exploding a temporary cofferdam protecting the Arizona tunnels while at the same time dumping rubble into the river until its natural course was blocked. Following the completion of the dam, the entrances to the two outer diversion tunnels were sealed at the opening and halfway through the tunnels with large concrete plugs. The downstream halves of the tunnels following the inner plugs are now the main bodies of the spillway tunnels. The inner diversion tunnels were plugged at approximately one-third of their length, beyond which they now carry steel pipes connecting the intake towers to the power plant and outlet works.
Hoover Dam | River diversion
For the dam to rest on solid rock, it was necessary to remove accumulated erosion soils and other loose materials in the riverbed until sound bedrock was reached. Work on the foundation excavations was completed in June 1933. During this excavation, approximately of material was removed. Since the dam was an arch-gravity type, the side-walls of the canyon would bear the force of the impounded lake. Therefore, the side-walls were excavated too, to reach virgin rock, as weathered rock might provide pathways for water seepage. Shovels for the excavation came from the Marion Power Shovel Company. The men who removed this rock were called "high scalers".
Hoover Dam | Groundworks, rock clearance and grout curtain
The smaller generators were used to serve smaller communities at a time when the output of each generator was dedicated to a single municipality, before the dam's total power output was placed on the grid and made arbitrarily distributable. Before water from Lake Mead reaches the turbines, it enters the intake towers and then four gradually narrowing penstocks which funnel the water down towards the powerhouse. The intakes provide a maximum hydraulic head (water pressure) of as the water reaches a speed of about . The entire flow of the Colorado River passes through the turbines. The spillways and outlet works (jet-flow gates) are rarely used.
Hoover Dam | Power plant and water demands
Before the dam could be built, the Colorado River needed to be diverted away from the construction site. To accomplish this, four diversion tunnels were driven through the canyon walls, two on the Nevada side and two on the Arizona side. These tunnels were in diameter. Their combined length was nearly 16,000 ft, or more than . The contract required these tunnels to be completed by October 1, 1933, with a $3,000-per-day fine to be assessed for any delay. To meet the deadline, Six Companies had to complete work by early 1933, since only in late fall and winter was the water level in the river low enough to safely divert.
Hoover Dam | River diversion
Davis Dam is a dam on the Colorado River about downstream from Hoover Dam. It stretches across the border between Arizona and Nevada. Originally called Bullhead Dam, Davis Dam was renamed after Arthur Powell Davis, who was the director of the U.S. Bureau of Reclamation from 1914 to 1923. The United States Bureau of Reclamation owns and operates the dam, which was completed in 1951. Davis Dam impounds the Colorado River and forms Lake Mohave. Davis Dam is a zoned earth-fill dam with a concrete spillway, in length at the crest, and high. The earth fill dam begins on the Nevada side, but it does not extend to the Arizona side on the east.
Davis Dam | Introduction
The jet-flow gates, located in concrete structures above the river and also at the outlets of the inner diversion tunnels at river level, may be used to divert water around the dam in emergency or flood conditions, but have never done so, and in practice are used only to drain water from the penstocks for maintenance. Following an uprating project from 1986 to 1993, the total gross power rating for the plant, including two 2.4 megawatt Pelton turbine-generators that power Hoover Dam's own operations is a maximum capacity of 2080 megawatts. The annual generation of Hoover Dam varies. The maximum net generation was 10.348 TWh in 1984, and the minimum since 1940 was 2.648 TWh in 1956.
Hoover Dam | Power plant and water demands
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 upstream, but the final decision was to build the dam 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 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.
Glen Canyon Dam | Site preparations
An old hydroelectric dam (38.020972 N, 107.378837 W) that supplied power for the mine lies on the creek at the Ute-Ulay mine site. Called the Hidden Treasure Dam, it burst in 1973 causing flooding and pollution downstream. The dam still stands and is visible from the road, but with a big hole in it.
Henson Creek | Abandoned dam
The dam stands in an area where sandstone and shale overlay pre-Cambrian granite, schist and gneiss. It is situated at a narrows in the river valley where the Gunnison enters the upper reaches of the Black Canyon of the Gunnison. The dam has a volume of and the spillway intake structure has two radial gates. These discharge into a concrete-lined tunnel which in turn discharges through a flip bucket into a stilling basin.
Blue Mesa Dam | Description
This cave was drilled by miners working on Hoover Dam while it was being constructed. It is a deep cave with calcium carbonate crystals on the walls. At the end of the cave is a hot spring, which causes temperatures in the cave to reach . One prominent canyon that splits from this canyon south of the Hoover Dam is Boy Scout Canyon. Boy Scout Canyon has water running through it that is warmed from a geothermal source.
Black Canyon of the Colorado | Introduction
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 , topped with layers of sand and tar.
Hoover Dam | Power plant and water demands
The dam would serve mainly for hydropower production in conjunction with several others further upstream including Marble Canyon Dam, on the Colorado, Green and other rivers. Due to its enormous potential for environmental destruction and the dwindling flows of the Colorado River, the project stalled in 1968 after years of public opposition. However, the location is considered one of the best remaining sites for a large dam in the western United States.
Bridge Canyon Dam | Introduction
Englebright Dam is a high variable radius concrete arch dam on the Yuba River in the Sacramento River Basin, located in Yuba and Nevada Counties of California, USA. It was put into service in 1941 by the United States Army Corps of Engineers. The dam was constructed in 1941 for the primary purpose of trapping sediment derived from anticipated hydraulic mining operations in the Yuba River watershed. Hydraulic mining in the Sierra Nevada was halted in 1884 but resumed on a limited basis until the 1930s during the great depression under the California Debris Commission. Although no hydraulic mining in the upper Yuba River watershed resumed after the construction of the dam, the historical mine sites continued to contribute sediment to the river.
Englebright Dam | Introduction
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.
Hoover Dam | Labor force
The dam provided flows for a hydroelectric plant about downstream at the Big Bend Powerhouse, today submerged by the reservoir behind Oroville Dam. Canyon Dam was modified in 1927 and 1962 to increase its usable storage. Today the dam and reservoir, owned by Pacific Gas and Electric, supply water to the 41 megawatt Butt Valley Powerhouse and provide summer flow for six hydroelectric plants on the North Fork Feather River downstream.
Canyon Dam (California) | Introduction
The dam lies about to the east of Ash Fork, in Johnson Canyon, and about west of Williams, Arizona. It is near the former U.S. Route 66 and Interstate 40. About a mile upstream lies Stone Dam, a masonry structure constructed 13 years later. The Grand Canyon Railway originates in Williams, branching from the ATSF main that this dam served, and runs northeast to the Grand Canyon.
Ashfork-Bainbridge Steel Dam | Location
Each five-foot form contained a set of steel pipes; cool river water would be poured through the pipes, followed by ice-cold water from a refrigeration plant. When an individual block had cured and had stopped contracting, the pipes were filled with grout. Grout was also used to fill the hairline spaces between columns, which were grooved to increase the strength of the joints. The concrete was delivered in huge steel buckets and almost 7 feet in diameter; Crowe was awarded two patents for their design. These buckets, which weighed when full, were filled at two massive concrete plants on the Nevada side, and were delivered to the site in special railcars.
Hoover Dam | Concrete
As the city grew, it gathered additional features, including numerous stores, a hospital, and even a jeweler. It was intended to serve a maximum population of eight thousand, accounting for the workers' families; the peak workforce would eventually exceed 2,500 in the busiest phases of construction. The engineer in charge of the project would be Lem F. Wylie, who had worked on Hoover Dam and had previously designed six other USBR dams. Prior to and during construction, three separate grants were issued by the National Park Service to document and recover artifacts of historical cultures along the river. These went to University of Utah historian C.
Glen Canyon Dam | Site preparations
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 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. Although first proposed in the 1920s to generate hydroelectricity, work did not begin until the dam was incorporated as part of the U.S.
Marble Canyon Dam | Introduction
Even before Congress approved the Boulder Canyon Project, the Bureau of Reclamation was considering what kind of dam should be used. Officials eventually decided on a massive concrete arch-gravity dam, the design of which was overseen by the Bureau's chief design engineer John L. Savage. The monolithic dam would be thick at the bottom and thin near the top, and would present a convex face towards the water above the dam. The curving arch of the dam would transmit the water's force into the abutments, in this case the rock walls of the canyon. The wedge-shaped dam would be thick at the bottom, narrowing to at the top, leaving room for a highway connecting Nevada and Arizona.
Hoover Dam | Design, preparation and contracting
In 1888, Billy Breakenridge became surveyor for Maricopa County. He surveyed the Salt River for potential dam sites and in July 1889, he traveled with James McClintock, William J. Murphy, and John R. Norton to choose the best location. After a week on horseback, they reached Box Canyon, near the confluence of Tonto Creek and the Salt River. They recommended the location as the best site for a dam. One of the original five federal projects authorized on March 14, 1903, under the Newlands Reclamation Act of 1902, Roosevelt Dam was the first major project to be completed under the new federal reclamation program.
Theodore Roosevelt Dam | History
To protect the construction site from the Colorado River and to facilitate the river's diversion, two cofferdams were constructed. Work on the upper cofferdam began in September 1932, even though the river had not yet been diverted. The cofferdams were designed to protect against the possibility of the river's flooding a site at which two thousand men might be at work, and their specifications were covered in the bid documents in nearly as much detail as the dam itself. The upper cofferdam was high, and thick at its base, thicker than the dam itself. It contained of material. When the cofferdams were in place and the construction site was drained of water, excavation for the dam foundation began.
Hoover Dam | Groundworks, rock clearance and grout curtain
Navajo Dam is a dam on the San Juan River, a tributary of the Colorado River, in northwestern New Mexico in the United States. The high earthen dam is situated in the foothills of the San Juan Mountains about upstream and east of Farmington, New Mexico. It was built by the U.S. Bureau of Reclamation (Reclamation) in the 1960s to provide flood control, irrigation, domestic and industrial water supply, and storage for droughts. A small hydroelectric power plant was added in the 1980s. The dam is a major feature of the Colorado River Storage Project, which is designed to regulate water resources across the entire Upper Colorado River Basin.
Navajo Dam | Introduction
In 1922, the Reclamation Service presented a report calling for the development of a dam on the Colorado River for flood control and electric power generation. The report was principally authored by Davis, and was called the Fall-Davis report after Interior Secretary Albert Fall. The Fall-Davis report cited use of the Colorado River as a federal concern because the river's basin covered several states, and the river eventually entered Mexico. Though the Fall-Davis report called for a dam "at or near Boulder Canyon", the Reclamation Service (which was renamed the Bureau of Reclamation the following year) found that canyon unsuitable.
Hoover Dam | Planning and agreements
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 Imperial 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 would be reimbursed by the federal government.
Hoover Dam | Search for resources
Roosevelt Dam was built on the upper Salt River in the early 1900s. This dam decreased the amount of water entering the Gila River where the two rivers meet. During this same time, the amount of water in the Gila River was decreased. The loss of water in the rivers resulted in the loss of most of the healthy cottonwood and willow trees along this portion of the Gila River. These trees require a lot of water to stay healthy. A long drought during the 1940s and early 1950s, and increases in the amount of water being used, accelerated the loss of riparian habitats.
Powers Butte Wildlife Area | Management history and goals
The U.S. Reclamation Service (now the Bureau of Reclamation) conducted surveys of dam sites on the lower San Juan River in 1914, as part of the Boulder Canyon Project (the so-called "Bluff reservoir" was never built, after engineers determined that the high silt load of the lower San Juan would make a storage reservoir here useless within a short time). By the 1920s – with the oil boom spurring rapid growth in the Farmington area and food shortages impacting the Navajo Nation – the federal government recognized the need for a multi-purpose dam project on the upper San Juan River, which would later become Navajo Dam.
San Juan River (Colorado River tributary) | Dams and water projects
Parker Dam is a concrete arch-gravity dam that crosses the Colorado River downstream of Hoover Dam. Built between 1934 and 1938 by the Bureau of Reclamation, it is high, of which are below the riverbed (the deep excavation was necessary in order to reach the bedrock on which the foundation of the dam was built), making it the deepest dam in the world. The dam's primary functions are to create a reservoir, and to generate hydroelectric power. The reservoir behind the dam is called Lake Havasu and can store or over 210 billion US gallons. The dam straddles the Arizona-California state border at the narrows the river passes through between the Whipple Mountains in San Bernardino County, California and the Buckskin Mountains in La Paz County, Arizona.
Parker Dam | Introduction
Glen Canyon Dam would regulate river flow between Lee's Ferry and Lake Mead, where the Colorado drops some , allowing the future construction of two additional hydroelectric dams, at Marble Canyon and Bridge Canyon. These two dams would be partially inside Grand Canyon National Park. Glen, Marble and Bridge together would provide the power necessary to pump water to where it was needed in central Arizona. In 1963, Arizona's congressional delegation proposed these dams as part of the Central Arizona Project to accomplish these goals. The state of California opposed the project, as it would eliminate the "surplus" water in the Colorado (really the Upper Basin's yet unused supplies) it had gotten accustomed to using.
Glen Canyon Dam | Colorado River Storage Project
G.R. Schneider. The construction contracts for the dam were awarded to the Morrison-Knudsen company and the Utah Construction Company. Both companies had participated in the construction of the Grand Coulee Dam and Hoover Dam. Construction began in the spring of 1941 with the removal of of earth to expose the bedrock foundation and an additional had to be removed to stabilize it. This was accomplished using draglines and power shovels. Most of the smaller aggregate used in construction was removed from the sand and gravel bars of a twenty-mile (32 km) section of the White River. A quarry and crushing plant was required to create nearly 800,000 tons of larger aggregate.
Norfork Dam | Construction
In the 1950s and 1960s, there was a need for new electric generation in the Southwest to supply power to growing populations in southern California, Arizona and Nevada. The US Bureau of Reclamation also needed a large source of power for running the pumps of the planned Central Arizona Project (CAP). A number of power projects were initially considered to fill these needs, most notably Bridge Canyon and Marble Canyon hydroelectric dams on the Colorado River. However, the proximity of the proposed dams to the Grand Canyon raised opposition, initially from the National Park Service and then more vigorously from a coalition of environmental groups which promoted construction of a thermal or nuclear power plant as an alternative.
Navajo Generating Station | History
The dam's purpose is to re-regulate releases from Hoover Dam upstream, and facilitate the delivery of Colorado River water to Mexico. Bullhead City, Arizona, and Laughlin, Nevada, are located just below the dam along the river. Davis Camp is also nearby. Bullhead City was originally a construction town for workers building the dam. A road is located on the crest of the earth fill portion of the dam and a Forebay Bridge spans the Forebay. It was formerly part of Arizona State Route 68 to Nevada. In April 2004, the roadway was shut down to vehicle traffic. Pedestrian and bicycle traffic are permitted.
Davis Dam | Description
The two dams would generate a combined 12.2 billion kilowatt hours (KWh) annually with a total installed capacity between 2000 and 3000 megawatts (MW). In the 1940s, Reclamation began investigating potential sites for a dam in the lower Grand Canyon near the river's confluence with Diamond Creek, upstream of Lake Mead. A small tent city was erected along the Colorado River near Bridge Canyon, complete with "a tar-paper cook shack with tables, a walk-in refrigerator attached, and tents or sleeping accommodations for the men… a small generating plant which furnished lights and fans for the swamp-type air conditioners which were a necessity in this canyon." The site was only accessible by a boat trip up the Colorado River from Lake Mead, and was plagued by torrid heat, poor access, floods and long working hours.
Bridge Canyon Dam | Background
The old roadway is now an extension of the Heritage Trail system. Barriers have been placed on the former road at each end of the earthen dam. The facility is heavily patrolled by security forces who strictly enforce parking regulations. The Davis Dam Power Plant is a hydroelectric power plant located on the Arizona side of the dam, beside the inlet. The hydroelectric plant generates between 1 and 2 terawatt-hours of electricity annually. The plant has a capacity of and the tops of its five Francis turbines are visible from outside the plant. The plant's head is .
Davis Dam | Description
The western first of the route and Arizona side of the Hoover Dam are still accessible to public traffic, but can only be reached via US 93, SR 172 and Hoover Dam Access Road through Nevada. There is currently no open road for motorists to leave the Arizona side of the Dam, whilst remaining in the state.
U.S. Route 93 in Arizona | Hoover Dam temporary route
Six Companies, Inc. was a joint venture of construction companies that was formed to build the Hoover Dam on the Colorado River in Nevada and Arizona. They later built Parker Dam, a portion of the Grand Coulee Dam, the Colorado River Aqueduct across the Mojave and Colorado Deserts to urban Southern California, and many other large projects.
Six Companies, Inc. | Introduction
On October 15, 1956, President Dwight D. Eisenhower pressed a button on his desk in Washington, D.C., sending a telegraph signal that set off the first blast of dynamite at the portal of the right diversion tunnel. Drilling the tunnels through the porous Navajo sandstone abutting the dam site posed major problems for the excavation crews of the Mountain States Construction Company, which won the contract for the diversion tunnels in 1956. Transporting workers and equipment to the bottom of the canyon was extremely difficult. Initially, transport was done by barge from Wahweap Creek, but the fast current of the Colorado River could be dangerous.
Glen Canyon Dam | River diversion
The two dams would be operated as "cash register" power plants, meaning that sale of hydroelectricity would pay for their construction cost as well as provide funds for future reclamation projects. The power thus produced would be vital for pumping along the Central Arizona Project (CAP), which would lift water from the Colorado River near Lake Havasu to central and southern Arizona. The pumped water would reach as far as Tucson, which sits about higher than the Colorado River. The Bureau had even grander visions, too: eventually, this generated revenue would be necessary to fund water import projects from the Columbia River system to the Colorado River, which continues to face shortages due to over-appropriation of its flow.
Marble Canyon Dam | Project description
Gregory Crampton and anthropologist Jesse Jennings, and to the Museum of Northern Arizona. Crampton subsequently wrote several books and articles on his findings. The Museum of Northern Arizona funded an expedition by William Miller and Helmut Abt, in coordination with the Navajo Nation, to investigate historical artifacts. They discovered a petroglyph in the upper part of the canyon depicting the appearance of the Crab Nebula in 1054.
Glen Canyon Dam | Site preparations
The project itself was the indirect result of a system of agreements signed by the seven U.S. states and two Mexican provinces in the early 20th century dividing the flow of the Colorado River among them. Among the terms stated in the 1922 Colorado River Compact reserved for the Upper Basin states of Wyoming, Colorado, Utah and New Mexico and an equal amount for the Lower Basin states of Arizona, Nevada and California. Due to the Colorado's high year-to-year variations in flow, the upper basin could not fulfill the lower basin's allotments in dry years, and much water was wasted during wet years because of the lack of a means to impound it.
Flaming Gorge Dam | History and location
A number of sites sacred to the Navajo people would later be flooded with the filling of the lake. Other features to be demolished or relocated included the towns of Rosa and Los Arboles, several cemeteries along the Los Pinos River, and sections of the Denver and Rio Grande Western Railroad. The primary construction contract for the dam was awarded to Morrison-Knudsen, Henry J. Kaiser Company, and F&S Contracting Company on June 25, 1958 and work began a month later on July 30. The first facilities to be constructed were the water works allowing for diversion of the San Juan River.
Navajo Dam | History
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 above the Colorado River.
Course of the Colorado River | <a href="Nevada">Nevada</a>/Arizona
The construction of Hoover was a major step towards stabilizing the lower channel of the Colorado River, storing water for irrigation in times of drought, and providing much-needed flood control as part of a program known as the Boulder Canyon Project. Hoover was the tallest dam in the world at the time of construction and also had the world's largest hydroelectric power plant. Flow regulation from Hoover Dam opened the doors for rapid development on the lower Colorado River; Imperial and Parker dams followed in 1938, and Davis Dam was completed in 1950. Completed in 1938 some above Yuma, Imperial Dam diverts nearly all of the Colorado's flow into two irrigation canals.
Colorado River | Lower Basin development, 1930s–1950s
Theodore Roosevelt Dam is a dam on the Salt River located northeast of Phoenix, Arizona. The dam is high and forms Theodore Roosevelt Lake as it impounds the Salt River. Originally built between 1905 and 1911; the dam was renovated and expanded in 1989–1996. The dam is named after President Theodore Roosevelt. Serving mainly for irrigation, water supply, and flood control, the dam also has a hydroelectric generating capacity of 36 megawatts.
Theodore Roosevelt Dam | Introduction
There were 112 deaths reported as associated with the construction of the dam. The first was surveyor John Gregory ("J.G.") Tierney who drowned on December 20, 1922 in a flash flood, while looking for an ideal spot for the dam. The official list's final death occurred on December 20, 1935, when Patrick Tierney, electrician's helper and the son of J.G. Tierney, fell from one of the two Arizona-side intake towers. Included in the fatality list are three workers who took their own lives on site, one in 1932 and two in 1933. Of the 112 fatalities, 91 were Six Companies employees, three were Bureau of Reclamation employees, and one was a visitor to the site; the remainder were employees of various contractors not part of Six Companies.
Hoover Dam | Construction deaths
Electricity from the dam's powerhouse was originally sold pursuant to a fifty-year contract, authorized by Congress in 1934, which ran from 1937 to 1987. In 1984, Congress passed a new statute which set power allocations to southern California, Arizona, and Nevada from the dam from 1987 to 2017. The powerhouse was run under the original authorization by the Los Angeles Department of Water and Power and Southern California Edison; in 1987, the Bureau of Reclamation assumed control. In 2011, Congress enacted legislation extending the current contracts until 2067, after setting aside 5% of Hoover Dam's power for sale to Native American tribes, electric cooperatives, and other entities.
Hoover Dam | Power distribution
Bureau of Reclamation (USBR)'s Pacific Southwest Water Plan in the 1940s for its Central Arizona component. Together with Bridge Canyon Dam, located at the lower end of the Grand Canyon, it would have provided the hydroelectric power necessary to lift Colorado River water from Lake Havasu to central Arizona's farms and cities, including Phoenix and Tucson. The two dams would have operated as "cash register" facilities to provide funds for future reclamation projects through the sale of cheap hydropower. After a series of studies and site investigations, the dam was abandoned as a project in order to facilitate legislation creating the Central Arizona Project.
Marble Canyon Dam | Introduction
The 1927 Mississippi flood made Midwestern and Southern congressmen and senators more sympathetic toward the dam project. On March 12, 1928, the failure of the St. Francis Dam, constructed by the city of Los Angeles, caused a disastrous flood that killed up to 600 people. As that dam was a curved-gravity type, similar in design to the arch-gravity as was proposed for the Black Canyon dam, opponents claimed that the Black Canyon dam's safety could not be guaranteed. Congress authorized a board of engineers to review plans for the proposed dam. The Colorado River Board found the project feasible, but warned that should the dam fail, every downstream Colorado River community would be destroyed, and that the river might change course and empty into the Salton Sea.
Hoover Dam | Planning and agreements
The dam site has an active earthquake fault nearby, and the original 1925 dam was seismically vulnerable. If the dam had collapsed when full, it would have flooded parts of Fremont, California with a wall of water high. Dam regulators for the state of California restricted the capacity of the original dam in 2001, to mitigate the seismic threat. The capacity of the original dam was limited to about one-third of the nominal 100,000 acre-feet (120 million cubic meters). To restore lost capacity, the San Francisco Public Utilities Commission constructed a replacement dam located downstream from the original 1925 dam.
Calaveras Reservoir | Dam replacement
The lake appears again intact with that name on a September 1911 reprint of a U. S. Geological Survey, Reconnaissance Map, Arizona, Nevada, California, Camp Mohave Sheet, Edition of March 1892, reprinted. The lake has since dried up, after being cut off from the spring flooding of the river, following the construction of the Hoover Dam.
Beaver Lake (Nevada) | History
With this technique, Crowe built some of the largest dams in the American west, including the Hoover Dam, Parker Dam downstream from Hoover; Copper Basin and Gene Wash Dams on the Colorado Aqueduct system; and Shasta Dam in Northern California. All these dams were important but none approached the mythic scale or mystique of Hoover Dam.
Frank Crowe | Introduction
The outlet works, located at the base of the dam, are fed by sixteen diameter conduits capable of discharging . The emergency spillway is located to the northwest of the dam and comprises a concrete overflow weir with a capacity of .
Santa Fe Dam | Statistics
Because of the new roads and bridge built for use during construction, it has become the gateway to the Glen Canyon National Recreation Area and Lake Powell, attracting more than 3 million visitors per year. Page is also the home of two of the largest electrical generation units in the western United States. Glen Canyon Dam has a 1,288,000-kilowatt capacity when fully online. The other power plant to the southeast is the Navajo Generating Station, which ceased operations in 2019. It was a coal-fired steam plant with an output capability of 2,250,000 kilowatts.
Page, Arizona | History
The dam eliminated the natural flooding, threatening many species adapted to the flooding, including both plants and animals. The construction of the dam devastated the populations of native fish in the river downstream from the dam. Four species of fish native to the Colorado River, the Bonytail chub, Colorado pikeminnow, Humpback chub, and Razorback sucker, are listed as endangered.
Hoover Dam | Environmental impact
In the 1940s and early 1950s, the United States Bureau of Reclamation planned to construct a series of Colorado River dams in the rugged Colorado Plateau province of Colorado, Utah, and Arizona. Glen Canyon Dam was born of a controversial damsite the Bureau selected in Echo Park, in what is now Dinosaur National Monument in Colorado. A small but politically effective group of objectors, led by David Brower of the Sierra Club, succeeded in defeating the Bureau's bid, citing Echo Park's natural and scenic qualities as too valuable to submerge. By agreeing to a relocated damsite near Lee's Ferry between Glen and Grand Canyons, however, Brower did not realize what he had gambled away.
Lake Powell | History
In the latter half of 1936, water levels in Lake Mead were high enough to permit power generation, and the first three Allis Chalmers built Francis turbine-generators, all on the Nevada side, began operating. In March 1937, one more Nevada generator went online and the first Arizona generator by August. By September 1939, four more generators were operating, and the dam's power plant became the largest hydroelectricity facility in the world. The final generator was not placed in service until 1961, bringing the maximum generating capacity to 1,345 megawatts at the time. Original plans called for 16 large generators, eight on each side of the river, but two smaller generators were installed instead of one large one on the Arizona side for a total of 17.
Hoover Dam | Power plant and water demands
A total of of concrete was used in the dam before concrete pouring ceased on May 29, 1935. In addition, were used in the power plant and other works. More than of cooling pipes were placed within the concrete. Overall, there is enough concrete in the dam to pave a two-lane highway from San Francisco to New York. Concrete cores were removed from the dam for testing in 1995; they showed that "Hoover Dam's concrete has continued to slowly gain strength" and the dam is composed of a "durable concrete having a compressive strength exceeding the range typically found in normal mass concrete".
Hoover Dam | Concrete
Owyhee's construction served as a prototype for the larger Hoover Dam on the Colorado River, including the use of refrigeration to cool the concrete. The dam cost $6,000,000, with the total reclamation project costing $18,000,000. Owyhee was designed by Frank A. Banks, who also designed other dams such as the Grand Coulee Dam on the Columbia River. In the 1980s, electricity-generating capabilities were added to the dam. From 1990 to 1993, the dam was remodeled. Since the height of the dam made a fish ladder impractical, the dam closed off the Owyhee Chinook salmon runs that used to swim as far upstream as Nevada.
Owyhee Dam | History
The Hells Canyon Dam powerhouse contains three generating units, with a total nameplate capacity of . Power generation began with two units in 1967, the third came on line the following year. Lacking passage for migrating salmon, the three dams of the Hells Canyon Project blocked access by anadromous salmonids to a stretch of the Snake River drainage basin from Hells Canyon Dam up to Shoshone Falls, which naturally prevents any upstream fish passage to the upper Snake River basin.
Hells Canyon Dam | Introduction
The total, , was based on only thirty years of streamflow records starting in the late 1890s. It was believed to represent the annual flow as measured at Lee's Ferry, Arizona (the official dividing point of the upper and lower basins), downstream of present-day Glen Canyon Dam. As it turned out, the early 20th century was one of the wettest periods in the last 800 years. The dependable natural flow past Lees Ferry is now believed to be about . The general consensus among inhabitants of the Colorado River basin and government officials was that a high dam had to be built on the Colorado to control floods and provide carry-over water storage for times of drought.
Glen Canyon Dam | The need for a dam
In August 1927, the US Congress authorized the building of a dam in the canyon of the Owyhee River. Construction of the dam began in 1928 to provide water for irrigation projects. It was built on a foundation of massive rhyolite, massive pitchstone, and associated unmassive pitchstone agglomerate geologic formations adjacent to the Owyhee Mountains. A project of the Bureau of Reclamation, they hired General Construction Company from Seattle to build the dam. Former Oregonian and then United States President Herbert Hoover dedicated what was the highest dam of its type in the world on July 17, 1932. Secretary of the Interior Ray Lyman Wilbur delivered Hoover's message at the dam.
Owyhee Dam | History
The work at the lower site at river mile 39.5 left two drifts measuring about by and about deep in the cliffs on either side of the river, together with 32 drill holes in the river bed. At the upper site, about upstream at river mile 32.8, there were a total of 35 drill holes and two drifts and deep. The work sites were accessed by an aerial tram from the rim. Although the lower site was preferred due to an additional of hydraulic head and potentially 45% larger reservoir than was possible at the upper site, it required more work to remediate weak rock joints.
Marble Canyon Dam | Exploration
Increased security concerns by the government have led to most of the interior structure being inaccessible to tourists. As a result, few of True's decorations can now be seen by visitors. Visitors can only purchase tickets on-site and have the options of a guided tour of the whole facility or only the power plant area. The only self-guided tour option is for the visitor center itself, where visitors can view various exhibits and enjoy a 360-degree view of the dam.
Hoover Dam | Roadway and tourism
A retaining wall was poured on the upstream side to prevent water seepage into the foundation hole, and the granite was scoured and artificially roughened to prepare for receiving concrete. The concrete for the dam was processed in a plant located shortly upstream from the construction site, with sand and rock excavated from abundant alluvial deposits in the Hetch Hetchy valley. This was mixed with cement shipped in on the Hetch Hetchy Railroad and local boulders ranging from to several yards (metres) in diameter to produce a cyclopean construction material for the dam. Beginning in September 1921, the concrete was hoisted up a tower on the south side of the gorge, from which it could flow down movable chutes by gravity to the construction site.
O'Shaughnessy Dam (California) | Construction
The Flaming Gorge Unit consists of the Flaming Gorge Dam and the Flaming Gorge Reservoir, and the dam's powerplant. The dam impounds the Green River near Dutch John, Utah. Portions of the reservoir spill over into Southern Wyoming Near the City of Green River. Completed in 1964, the dam provides water storage and hydroelectric generation, as well as flood control on the Green River, the primary tributary to the Colorado. The powerplant in the dam has a capacity of 153 megawatts or about 8.5% of the entire system.
Colorado River Storage Project | Flaming Gorge Unit
The Virgin River Gorge is located just to the east of Beaver Dam.
Beaver Dam, Arizona | Contemporary Beaver Dam
The dam forms Apache Lake as it impounds the Salt River. The dam and reservoir are located downstream from the Theodore Roosevelt Dam, and upstream from the Mormon Flat Dam.
Horse Mesa Dam | Reservoir
The inner tunnels' outlets are equipped with gates that can be closed to drain the tunnels for maintenance.
Hoover Dam | River diversion
Because of the isolated location, acquiring the land at the dam and reservoir sites was not particularly difficult, but there were a few disputes with ranchers and miners in the area (many of the Navajo Nation). Much of the land acquired for the dam was through an exchange with the Navajo, in which the tribe ceded Manson Mesa south of the dam site for a similar-sized chunk of land near Aneth, Utah, which the Navajo had long coveted. In the early stages of construction, the only way to cross Glen Canyon was a suspension footbridge made of chicken wire and metal grates.
Glen Canyon Dam | Site preparations
In the late 1940s, crews led by Bureau engineer Bert Lucas began to survey Marble Canyon and identified at least two suitable dam sites, one below Lee's Ferry and the second at . A road had to be built to connect the nearest highway to "one of the most inaccessible damsites ever explored by Bureau of Reclamation engineers". In 1949 the Bureau opened bids for the construction of a cableway to transport workers and materials down into the remote canyon at Mile 32.8. Once the cableway was completed, a temporary camp was set up on the bottom of the gorge, and exploratory drilling work commenced in 1951.
Marble Canyon Dam | Exploration
The dam is a tall concrete gravity type and has a length of . The crest of the dam is while the base is . The dam structure compromises a total of of concrete. The dam's spillway is located on its central portion and is controlled by four radial gates. It has a maximum discharge of . Adjacent to the spillway is the dam's power plant which contains three 16.5 MW Francis turbine generators for an installed capacity of 50 MW. Each turbine is fed with water by a diameter penstock. At a normal elevation of , the reservoir contains of water.
Canyon Ferry Dam | Design
As a result, the proposed dams were abandoned in favor of the Navajo Power Project, consisting of the Navajo Generating Station (NGS) along with the Kayenta mine, Black Mesa & Lake Powell (BM&LP) Railroad, and of 500 kV transmission lines. The site selected for the new power plant was about six miles (10 km) east of Glen Canyon Dam and three miles (5 km) south of Lake Powell on of land leased from the Navajo Nation. The site was close to a source of competitively priced fuel and a reliable source of surface water for cooling. The nearby city of Page and U.S.
Navajo Generating Station | History
The dam is protected against over-topping by two spillways. The spillway entrances are located behind each dam abutment, running roughly parallel to the canyon walls. The spillway entrance arrangement forms a classic side-flow weir with each spillway containing four and steel-drum gates. Each gate weighs and can be operated manually or automatically. Gates are raised and lowered depending on water levels in the reservoir and flood conditions. The gates cannot entirely prevent water from entering the spillways but can maintain an extra of lake level. Water flowing over the spillways falls dramatically into , spillway tunnels before connecting to the outer diversion tunnels, and reentering the main river channel below the dam.
Hoover Dam | Spillways
One of the first federal projects undertaken by the National Reclamation Act was the construction of the Theodore Roosevelt Dam in Arizona, which would provide the vital water supply and hydroelectric power to promote the growth of the Phoenix metropolitan area. Although the remote site of this future dam proved to be a logistical nightmare, the solution to this problem was the construction of the Apache Trail. Thus, the Apache Trail served as the critical supply road, facilitating the transport of materials and equipment to the dam site.
Apache Trail | The Theodore Roosevelt Dam
Nine main access points to the lake are available. On the west are three roads from the Las Vegas metropolitan area. Access from the northwest from Interstate 15 is through the Valley of Fire State Park and the Moapa River Indian Reservation to the Overton Arm of the lake. The lake is divided into several bodies. The large body closest to the Hoover Dam is Boulder Basin. The narrow channel, which was once known as Boulder Canyon and is now known as The Narrows, connects Boulder Basin to Virgin Basin to the east. The Virgin River and Muddy River empty into the Overton Arm, which is connected to the northern part of the Virgin Basin.
Lake Mead | Geography
Treshow was hired as a designer of construction tools, to work on the Hoover Dam. During the construction of the Boulder (now Hoover) Dam between 1930 and 1936 he designed and supervised the installation of the equipment that pumped concrete - more than 8 million tons of it - from where it was mixed to the dam site. "Something over a mile as I recall," says his son, Ken. Treshow switched to nuclear reactor design and engineering after World War II.
Mike Treshow | Hoover Dam
Mammoth Pool Dam is a hydroelectric dam located on the San Joaquin River in the southern Sierra Nevada mountain range of California, about northeast of Fresno. It forms Mammoth Pool Reservoir and lies within the Sierra National Forest. The dam and reservoir were named after a large natural pool in the river that was once located above the present dam site.
Mammoth Pool Dam | Introduction
Together, the two dams would utilize most of the elevation drop between Lee's Ferry and Lake Mead, which represents one of the biggest untapped hydroelectric potentials in the United States. A number of accessory lakes or pools were projected in the adjacent Deer Creek drainage, or possibly at a dam on Kanab Creek. The power station at Deer Creek would have been at the head of the reservoir backed up by the never-built Bridge Canyon Dam. By the 1960s the tunnel project had been dropped in favor of a 600 MW power station at the dam's base, reducing the project's costs considerably.
Marble Canyon Dam | Project description
Rollins Dam (National ID # CA00255) is a dam on the border of Nevada and Placer counties in northern California, in the United States. The earthen dam was constructed in 1965 by the Nevada Irrigation District, with a height of , and a length of at its crest. It impounds the Bear River, a tributary of the Feather River, for hydropower, flood control, irrigation water storage, and municipal water use. The dam is one of the ten facilities owned and operated by the Nevada Irrigation District. The dam is part of the Yuba-Bear Hydroelectric Project. The reservoir it creates, Rollins Reservoir, has a normal water surface of , and a maximum capacity of 66,000 acre-feet.
Rollins Dam | Introduction
Normal storage is about one tenth that volume. Recreation is limited. There is no access to the water. All land surrounding the reservoir, except a small day-use area with picnic facilities and a scenic overlook, is the property of Santa Ana Pueblo, with restricted access.
Jemez Canyon Dam | Introduction
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. The delta's estuary, which once had a freshwater-saltwater mixing zone stretching south of the river's mouth, was turned into an inverse estuary where the level of salinity was higher close to the river's mouth. The Colorado River had experienced natural flooding before the construction of the Hoover Dam.
Hoover Dam | Environmental impact
Flaming Gorge Dam is a concrete thin-arch dam on the Green River, a major tributary of the Colorado River, in northern Utah in the United States. Flaming Gorge Dam forms the Flaming Gorge Reservoir, which extends into southern Wyoming, submerging four distinct gorges of the Green River. The dam is a major component of the Colorado River Storage Project, which stores and distributes upper Colorado River Basin water. The dam takes its name from a nearby section of the Green River canyon, named by John Wesley Powell in 1869. It was built by the U.S. Bureau of Reclamation between 1958 and 1964.
Flaming Gorge Dam | Introduction
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, downstream of Lee's Ferry and at the uppermost end of Lake Mead. First proposed in the 1920s, the project was seriously considered by the U.S. Bureau of Reclamation for a period of over twenty years from the early 1950s to 1968. If built, the dam would have stood high, forming a reservoir stretching more than upstream, including along the border of Grand Canyon National Park.
Bridge Canyon Dam | Introduction
Pardee Dam is a -high structure across the Mokelumne River which marks the boundary between Amador and Calaveras Counties, located in the foothills of the Sierra Nevada approximately northeast of Stockton.
Pardee Dam | Introduction
The force of the water at the left tunnel eroded concrete near the diversion plug, a device that blocked the diversion tunnel used during construction. The Bureau of Reclamation was concerned that the water would eventually erode the diversion plug altogether, creating a connection to the reservoir floor. This uncontrolled spillage would cause the reservoir to drain, creating a catastrophe. As the discharges from Glen Canyon Dam reached almost per second, with per second racing through the left spillway, the of flood storage space behind Hoover Dam downstream was exhausted.
Risks to the Glen Canyon Dam | Diversion tunnel threatened
"Mongolian" (Chinese) labor was prevented by the construction contract, while the number of blacks employed by Six Companies never exceeded thirty, mostly lowest-pay-scale laborers in a segregated crew, who were issued separate water buckets. As part of the contract, Six Companies, Inc. was to build Boulder City to house the workers. The original timetable called for Boulder City to be built before the dam project began, but President Hoover ordered work on the dam to begin in March 1931 rather than in October. The company built bunkhouses, attached to the canyon wall, to house 480 single men at what became known as River Camp.
Hoover Dam | Labor force
Navajo Dam was authorized by Congress in the Colorado River Storage Project Act of April 11, 1956, which also authorized Glen Canyon Dam and numerous irrigation and power projects along the Green River, Gunnison River and other tributaries. The initial authorization for Navajo Dam did not include the Navajo irrigation project, which was authorized much later, in June 1962, along with the San Juan-Chama diversion project. Preparatory work at the Navajo Dam site started on October 8, 1956 with archaeological excavations of Native American sites along the canyons and bottom lands of the San Juan River; however, these investigations were limited in scope and only preserved a handful of artifacts from the area.
Navajo Dam | History
The eastern Snake River Plain is almost entirely underlain by basalt erupted from large shield volcanos on top of rhyolitic ash-flow tuff and ignimbrites. The tuff, a late-Cenozoic volcanic rock is 1.9 million years old. The dam site is composed of basalt and rhyolite, both of which are considered unsuitable for dam construction because of their high permeability. This was confirmed by long-term pump-in tests at rates of per minute. Test cores, drilled by engineers and geologists employed by the Bureau of Reclamation, showed that the canyon rock at the dam site is highly fissured and unstable, particularly on the right side (as one faces the direction of flow).
Teton Dam | History and geology
Explosive charges were placed in the crest of the main dam, to be used if the overflow occurred, thus keeping the lowest point at the dam. The dike held and the charges were not needed, but did have to be removed by explosives experts in 1949. An auxiliary dike was built at the location in 1910 to develop the reservoir's full capacity. The potential overtopping gave rise to sensational stories in Denver newspapers and caused annual nervousness in Casper downstream for a number of years thereafter. The Fremont Canyon Powerplant was built between 1958 and 1961, part of the Glendo Unit of the Pick–Sloan Missouri Basin Project.
Pathfinder Dam | History