LAKE MEAD The Story of Boulder Dam

A Significant Prophecy

WHEN the Committee on Irrigation and Reclamation of the United States Senate in March 1928 endorsed the construction of multi-benefit Boulder Dam it made this significant prophecy:

"A mighty river, now a source of destruction, is to be curbed and put to work in the interest of society."

Boulder Dam was built to bring the following major benefits:

First, flood control. Protection for the lives and property of 100,000 people who lived at the mercy of an unbridled river.

Second, water for the irrigation of nearly 2,000,000 acres of rich land, a third of which was already under intensive cultivation and completely dependent on the water supply.

Third, water for domestic, industrial, and municipal use by the rapidly expanding population of the southern California coastal region.

Fourth, elimination of damaging, clogging silt deposits, whose removal was costing more than $1,000,000 annually.

Fifth, improvement of navigation.

Sixth, a national playground and recreational area.

Seventh, a new wildlife and bird refuge.

Eighth (on a last-but-not-least basis), the generation of low-cost power.

On September 30, 1935, less than 5 years after the construction appropriation, in dedicating Boulder Dam, President Franklin D. Roosevelt said:

"This is an engineering victory of the first order—another great achievement of American resourcefulness, skill and determination. This is why I congratulate you who have created Boulder Dam and on behalf of the Nation say to you 'Well done.'"

Volumes have been written of the engineering and physical features of an undertaking that conquered America's most dangerous stream and conserved its vast resources for the good of mankind. The conservation of these resources, the actual work of the dam, is a story in itself.

Flood control is an important chapter of that story. In less than 5 years from the first construction appropriation, Boulder Dam took control over the floods of the Colorado River.

On Lake Mead

Lake Mead Swallows the Floods

Set in the midst of the brown, red and purple mountains and mesas of the Southwest, shining in the bright western sun, a great clear-blue lake has been formed behind Boulder Dam. It is Lake Mead,¹ Boulder Dam's reservoir, the largest artificial lake in the world.

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¹Named for Dr. Elwood Mead, Commissioner, Bureau of Reclamation, 1924-36.

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This useful and beautiful lake now gathers to itself the wild, muddy floods of the Colorado, so destructive and expensive in the years before the building of Boulder Dam. The lake has a storage capacity of 32,359,274 acre-feet—enough to store more than 2 years of the Colorado's average flow—enough to supply every man, woman and child in the United States with 80,000 gallons of water each.

When full, Lake Mead has a depth of 589 feet, a shoreline of 550 miles, and a water surface area of 227 square miles. It extends up stream 115 miles above the dam.

Panoramic perspective of Boulder Dam area. (click on image for a PDF version)

With its great reservoir the dam controls not only the flashy, lesser floods which may occur during any month of the year, but also the great flood-tide run-off occurring in the spring and summer months.

The upper 72 feet of Boulder Dam's reservoir capacity—9,500,000 acre-feet—is reserved for its flood control work. This capacity is not encroached upon for the storage of water except to control the discharge below the dam to the amount that can be carried safely through the lower valleys without the expenditure of excessive amounts of money for protective levee work.

Maximum discharge of Colorado River at Boulder Dam. (click on image for a PDF version)

No longer at the mercy of the Colorado are the homes and highly productive land in the Imperial, Coachella, Yuma, and Palo Verde valleys which pioneers had carved from the desert, representing property values of a quarter of a billion dollars.

With Lake Mead functioning, the large floods passing the dam site are reduced from 200,000 cubic feet per second to 45,000, and the extreme floods from 300,000 cubic feet per second to about 75,000. With this control established, 100,000 residents of the valleys below need no longer fear the Colorado, provided the channels and levees carrying away even the greatly reduced discharges are maintained.

Imperial Valley winter lettuce, row on row>

No More Drought

The second great benefit from Boulder is the provision of an adequate, reliable supply of water for irrigation.

No more does this giant of a western desert stream fluctuate each year through a cycle of a roaring, flood-swollen spring torrent fed by melting northern snows to a sandy-bottomed sluggish creek during long dry summer and autumn months.

No more is the Colorado's water—as precious as the gold that drew the Forty-niners westward nearly a century ago—wasted unused into the sea during flood season. Instead, the Colorado's water is put to use.

The irrigated Southwest is the all-year vegetable and fruit basket of the United States. With an adequate supply of water for artificial application, the rich soil and warm climate make the Imperial and other valleys veritable Gardens of Eden. From farms under irrigation in the Southwest come in the dead of winter quantities of healthful green vegetables, citrus fruits essential to the varied American diet, figs and dates, grapes and raisins, olives, avocados, walnuts, almonds, and other exotic fruits and nuts once entirely imported from tropical lands.

It is estimated that about 1,900,000 acres of irrigable lands are located below Boulder Dam, in the United States. At present there are about 660,000 acres under cultivation, of which 450,000 lie in the Imperial and Coachella Valleys.

Without Boulder Dam the extension of irrigation in these lands was out of the question. The natural flow of the river was already overtaxed during the peak of the irrigation season. During a year such as 1934, when the Colorado River discharge was a little over 4,000,000 acre-feet, about one-quarter of the expected normal, there was serious shortage. Crops valued at $10,000,000 were lost. Entire communities were jeopardized.

Today the supply of irrigation water stored by Boulder Dam is adequate for all irrigation use. Lake Mead impounds more than five years' full irrigation supply for the irrigated farm lands below. Southwestern irrigation farmers need no longer dread the specter of drought, of a river running dry.

One of the 600,000 visitors during 1940 gazing at the dam

A Vital Metropolitan Water Supply

At the same time, opportunity for a new home and decent livelihood can be opened to 20,000 or more families on irrigated farms claimed from the desert. Communities and towns will also arise among these farms and offer a means of living to thousands of other families.

A third important benefit derived from Boulder Dam's construction is the provision of a metropolitan water supply vital to the economic welfare and growth of southern California and 13 of its coastal cities—Anaheim, Beverly Hills, Burbank, Compton, Fullerton, Glendale, Long Beach, Los Angeles, Pasadena, San Marino, Santa Ana, Santa Monica, and Torrance.

Southern California is a semiarid region. Average rainfall near the coast is 15 inches annually, far less than that required for dependable agricultural development, to say nothing of the needs of modern industrial cities. In other areas the average annual rainfall shades down to 3 inches.

For many years the people of the southern California coastal plain had been pumping out of underground reserves 200,000,000 gallons a day more than Nature or man replaced. The result was a dangerous depletion of local water resources.

A large supply of additional water was urgently required to sustain the 13 cities and their growing industries. In these cities and their suburban and rural sections resided nearly 3,000,000 people. Property values were assessed at $2,800,000,000.

The destiny of all this area depended on an additional supply of water.

The only available source of supply large enough was the Colorado River. Without regulation the Colorado was useless.

By regulating the Colorado River, Boulder Dam assured this supply and opened the river to this vital use.

Storage in Lake Mead. (click on image for a PDF version)

With Boulder Dam in control of the Colorado it was possible to construct Parker Dam 155 miles below to form a forebay from which an aqueduct could draw off the water needed.

The 13 cities combined to incorporate the Metropolitan Water District of southern California which floated a $220,000,000 bond issue to pay for the dam and aqueduct. The Bureau of Reclamation built the dam with funds advanced by the District and the District built the aqueduct.

Today the Colorado River Aqueduct carries Colorado River water over mountain and desert for 242 miles, through tunnels, conduits, canals, and siphons, to distribute it to the homes and industries of southern California.

It is the largest single domestic water supply system in the world. It has a capacity of 1,500 cubic feet per second or approximately a billion gallons daily.

Motorboating up through the canyons, Lake Mead

The Metropolitan Water District has a contract with the Government permitting it to draw 1,050,000 acre-feet of water annually from the Colorado River, water released at Boulder Dam. The charge for Lake Mead's water is nominal, 25 cents per acre-foot of 325,851 gallons.

According to the chief engineer and general manager of the Metropolitan Water District, Boulder and the aqueduct provide a supply of water "sufficient to meet the requirements of a population in excess of 7 millions"—more than twice the present population.

The soil of southern California is rich and fruitful, and the people energetic. It has been outstanding in the production of tangible wealth for the State and the Nation. The value of crops produced in Los Angeles County in 1930 exceeded that of any other county in the United States.

The new supply of water from Lake Mead has released for agricultural purposes much of the remaining underground reserves of the southern California coastal area. Boulder has made it possible for the entire region to grow and develop, industrially as well as agriculturally, and to continue to pour its contribution into the lifestream of the Nation.

Four happy fishermen and their Lake Mead catch

The Silt Menace Subdued

A fourth benefit of Boulder Dam is the elimination of hundreds of millions of tons of silt from the waters released at Boulder Dam.

The Colorado gets its name from its reddish-brown color, and the reddish-brown color comes from the silt carried in its turbulent waters. Engineers have estimated that the average flow of the river carries 330 tons of silt and sand past a given point every single minute of the day and night.

This silt not only obstructs the diversion works, canals, and ditches of those who wish to use the water, but its deposition is dangerous. Silt deposits result in the gradual building up of the ground elevation. A committee of the United States Senate in 1928 reported as follows:

The most powerful powerhouse in the world

"The river has an annual discharge at Yuma of more than 100,000 acre-feet of silt. This silt greatly aggravates the flood menace. No temporary works can be built to hold it. It was the silt deposit that built the deltaic ridge on which the river now flows. It was the silt deposit that filled the Bee River and Volcano Lake, so that the river could no longer be held at that point, and the same silt deposit will quickly fill the depression where the river now flows.

"The gradient to the north into Imperial Valley is much greater than that to the south into the Gulf, and when the depression is filled there is no means known which, at any cost within reason, can prevent the river from again flowing into the Imperial Valley.

"The dam proposed in this bill will catch and hold the silt. Most of the silt finding its way onto the delta is from and above the canyon section. If no other dams were provided on the river, the one proposed in this bill would retain all of the silt finding its way into the reservoir for a period of 300 years, and for more than 100 years before its storage capacity and usefulness would be seriously interfered with. As other dams are constructed on the river they will catch and retain the silt, thereby further extending the usefulness of the Boulder Canyon Reservoir."

Plan of power house

Reclamation engineers set aside 5 to 8 million acre-feet of Boulder Dam's reservoir capacity for the job of settling out the silt. The deep reservoir forms a natural trap for the silt swept down the river. The flow slackens as it enters the lake and the silt, heavier than the water, sinks to the bottom of the reservoir, leaving the water above clear. As the silt drops down into the deep and capacious bottom of Boulder Dam's reservoir, blue Lake Mead bears witness that the task is well performed.

Navigation on the Colorado

A fifth benefit from Boulder Dam's construction is the improvement of navigation on Lake Mead and on the river between Boulder Dam and Imperial Dam, the point of diversion for the new All-American Canal which leads Colorado River water to the Imperial Valley.

Technically, before the construction of Boulder Dam, the Colorado was considered a navigable stream, but under conditions of unregulated flow navigation was impracticable. The flow of the river at Black Canyon ordinarily varied from 3,000 cubic feet per second to 150,000. Sometimes the variation in flow was still more severe. In August 1934 the river dropped to 1,780 cubic feet per second, and in 1884 the flood is estimated to have been between 300,000 and 350,000 cubic feet per second. At low flow, the river channel shifted daily and made navigation out of the question except for very small boats. At flood stage, on the other hand, the river was unnavigable because of its high velocity.

With the river regulated by Boulder Dam the steady flow ranges from 12,000 to 20,000 cubic feet per second. The maximum flow to be expected is about 45,000 cubic feet per second, to control the usual seasonal floods. This may reach 75,000 cubic feet per second once in about 100 years. The Colorado can now actually be navigated.

A Nation's New Playground

A sixth and truly symbolical benefit resulting from Boulder Dam—a national instrument for the use and enjoyment of the people—is the creation of a new national playground.

Visitors to the lake come from all parts of the United States by every mode of transportation—train, plane, auto, bus, bicycle, and even boat.

The tourists numbered 600,000 during 1940. They used nearly 200,000 automobiles and more than 2,000 large sightseeing buses and nearly 1,500 airplanes, mostly large transports.

Lake Mead is considered worth traveling hundreds of miles to see. The 115-mile lake stretches past Fortification Hill, through narrow Boulder Canyon, through Virgin Canyon, Iceberg Canyon, past the white Grand Wash cliffs, and far into the Lower Granite Gorge amid high coloring and spectacular geological formations. The lake reaches up into the lower end of the Grand Canyon itself, opening up hitherto unseen scenic beauty. Previously these vistas were utterly inaccessible.

The lake has 550 miles of shoreline for camping, bathing, boating, and fishing. Although hot during the summer months the climate during the remainder of the year is ideal for outdoor enjoyment. The winter is especially delightful.

The recreational area created by Boulder Dam is a day's drive by automobile from Salt Lake City, Phoenix, Los Angeles, and other cities in the Southwest.

Precautions have been taken by the Bureau of Reclamation for the comfort and enjoyment of visitors. Roadways to the dam itself have been widened, protective safety walls built, and special guides provided for a tour of the dam and powerhouse. Motor boats are available for lake trips. A special visitors' building contains a large, elaborate model of the dam area, complete in every detail.

Fishing is one of the prime attractions. Lake Mead abounds in black bass, bluegill perch, crappies, and catfish. Fishermen are not confined the deep recesses of Lake Mead creates a perfect habitat for the beauties. For 45 miles downstream, with deep inviting pools along the way, the river water is as fresh and invigorating as a mountain rill.

Boulder Dam and Power Plant. (click on image for a PDF version)

Haven for Wildlife

Other wildlife flourishes in the Boulder Dam area also. This—the formation of a wildlife and waterfowl refuge—is a seventh beneficial result of building Boulder Dam.

The area has been officially designated as a wildlife refuge, with hunting forbidden. Nearly 650,000 acres of mountain and mesa surrounding Lake Mead offer haven to animals and birds. They are fostered and protected. Mountain sheep and Gambel quail thrive in the uplands.

Lake Mead and Lake Havasu (the Metropolitan Water District reservoir formed by Parker Dam 155 miles below Boulder) offer sanctuaries of considerable value in waterfowl conservation. The pintail and the mallard, the Canadian goose, the snowy egret, the sandpiper and other birds frequent the refuges.

Lake Havasu, located on the main flyway, is ideal. Ducks, geese, and other birds on their long annual migrations south and back find Lake Havasu's shallow waters a harbor of rest.

A huge generator—capable of supplying an entire city with electric light

Power and the Strength of the West

The eighth and one of the major benefits to the Southwest from the construction of Boulder Damn is the generation of low cost electric power.

The West has ever been the elbow room of our expanding Nation. Population increase has been faster, development has been surer. The population of Los Angeles increased from 50,000 in 1900 to more than 500,000 by 1920, to more than 1,200,000 by 1930, becoming the fifth largest city in the United States. Other cities in southern California were expanding proportionately.

This progress could continue only so long as water and power for expansion could be obtained.

The intensive agriculture in the southern California metropolitan area was developed by irrigation with underground water. This underground water was also drawn upon for domestic and manufacturing use by the growing cities and towns. The supply was endangered by continual overdrafts.

Power was needed, also, as well as water. During the decade and a half preceding passage of the Boulder Canyon Project Act, use of electric energy in southern California increased three times as rapidly as in the rest of the United States.

Both water and power were within reach and obtainable, being wasted in the roaring floods of the Colorado River. Instead of dealing death and destruction these floods could be transformed to an inexhaustible source of comfort and convenience for mankind.

The disastrous consequences of neglecting the conservation of a great natural resource like the waters of the Colorado River had been recognized for a quarter of a century. But the question was: How could this conservation be achieved? It would cost a hundred million dollars and more. Who would pay for it?

When plans for Boulder Dam were under consideration, the volume of power it could produce and the revenue it could return to the Treasury were adjudged large enough to make the construction pay for itself.

Power, then, made it possible to build Boulder Dam.

Generating unit cross-section

The Endless Tune of Untold Wealth

Boulder's gigantic hydroelectric plant is the largest now operating in the world. It is capable of supplying whole cities with light and power. High tension transmission lines radiate from Boulder Dam carrying electric energy for homes and farms, stores and factories, pumping plants, and mines and smelters. Nine giant generators today hum am endless tune of untold wealth—the myriad, creative wealth of hydroelectric power. More are being added yearly.

Boulder's installed capacity in 1940 was larger than that of the Russian Dnieprostroy development, larger even than that of Niagara Falls and Muscle Shoals combined. It totaled 704,800 kilowatts.

When all its 17 generators are installed, Boulder will have an installed capacity of 1,322,300 kilowatts and be able to generate nearly 6 billion kilowatt-hours of electricity annually.

With only 9 of its 17 generators installed and operating, Boulder Dam in 1940 generated 3 billion kilowatt-hours, about half the total power consumption of southern California, Arizona, and Nevada within transmission distance of Boulder.

Single-line diagram of power plant outlets. (click on image for a PDF version)

Increasing Power Generation

The income from Boulder's power plant has shown steady increase as the nine giant generators have been installed one after the other to meet the demand for electric energy. During 1936-37 Boulder income under temporary interim contracts (which disposed of power at secondary rates) totaled a quarter of a million dollars. The following fiscal year, 1937-38—the first under regular 50-year contracts for firm power—the gross income rose to nearly 3 million dollars. In 1938-39 it rose to nearly 4 million; in 1939-40, to 4-1/2 million.

The first big customer for Boulder power was the city of Los Angeles, to which energy was transmitted October 9, 1936. The city celebrated the event with a "Pageant of Light." Huge arc lights on the city hail blazed with electricity sent from Boulder 266 miles away. Regular service to Los Angeles started 2 weeks later on October 22, and as soon as possible three more generators for the city were installed.

The four generators created power for other municipalities in southern California as well. The city of Los Angeles operated them for Los Angeles, Pasadena, Burbank, and Glendale; Las Vegas and Boulder City, Nev., also obtained energy.

The following year, 1937, a generator went into operation for the Nevada-California Electric Corporation, a private utility supplying customers in southernmost California.

Two more generators went into operation in 1938, bringing the total to seven. They were destined for use by the Metropolitan Water District of southern California to pump Colorado River water to the 13 coastal cities. The construction of the Colorado River Aqueduct had not kept pace with Boulder Dam which was completed 2 years before schedule, however, so part of the power generated by the Metropolitan Water District units was sold to the Needles Gas & Electric Co. of Needles, Calif., and the Citizens' Utility Co. of Kingman, Ariz.

Power—over the hills and far away

The Southern California Edison Co., which serves consumers in seven counties of southern California, had a contract with the Government to take power beginning June 1, 1940, but at the company's request the Bureau's forces speeded up installation. Two generators for the company went into operation at Boulder months before schedule, in the summer and fall of 1939. They were hurried into service under a full load 24 hours a day as soon as they had been tested. A power shortage made it necessary. They brought the total number of generators in operation at Boulder to nine.

As new generators have been added, the generation of power at Boulder has increased year by year: In 1936 the plant generated 124 million kilowatt-hours; in 1937, 1,180 million kilowatt-hours; in 1938, 1,523 million kilowatt-hours; in 1939, 2,508 million kilowatt-hours; and in 1940, more than 3,000 million kilowatt-hours.

Boulder has 11 high-tension transmission lines extending from its power plant to customers hundreds of miles away. Three lines extend to Los Angeles 266 miles away. Another line extends 233 miles to Chino, Calif. A fifth line goes to San Bernardino, Calif., 222 miles distant. Other lines go to Hayfield, Calif.; Parker, Ariz.; Kingman, Ariz.; Needles, Calif.; Pioche, Nev.; Las Vegas, Nev.; and Boulder City, Nev.

Output and revenue of Boulder Dam Power Plant. (click on image for a PDF version)

Parker Dam, on the Colorado River 155 miles below Boulder, will aid in generating power for the Southwest. A capacity of 120,000 kilowatts will help supply the needs of Arizona. High-tension transmission lines already have been built from Parker Dam to Phoenix, Ariz., and to Blaisdell, Ariz.

Pending the installation of generating equipment at Parker, Boulder is filling the deficiency through the transmission line built to Parker Dam for construction power. Boulder energy is being relayed at Parker Dam deep into central Arizona where a power shortage had threatened the intensive agricultural development of the Salt River Valley.

Area benefitted by control of Colorado River. (click on image for a PDF version)

The Ramified Benefits

This distribution of low cost power from Boulder Dam throughout the Southwest is already showing material effect. In the midst of its ramified benefits, bound to multiply and become even more widespread through the years, certain significant facts already appear.

The introduction of Boulder power in 1936-37 was followed by a general lowering of rates. As of August 1, 1937, it was estimated that consumers in the city of Los Angeles were being saved $1,320,000 annually. Subsequent expansion of the city's municipal operations increased these savings still further.

Rotary International is welcomed by the Boulder City school band

Rates in Las Vegas, Nev., have been reduced from a maximum of 8 cents a kilowatt-hour to 3 cents. Schedules for commercial and industrial uses in Nevada have also been reduced. The Lincoln County Power District No. 1 delivers Boulder power in its area, 156 miles from the dam, at 8.5 mills.

The number of electric customers of the three major contractors for Boulder power—the city of Los Angeles, the Southern California Edison Co., and the Nevada-California Electric Corporation—increased nearly 30 percent from 1935 to 1940. In the 10 years ending 1945, the number is expected to double with approximately 1,300,000 residential, industrial and commercial consumers dependent on Boulder for 75 percent of their supply.

The population of the metropolitan area of southern California increased 27 percent from 1930 to 1940, while the estimated growth for the country at large in the same period was only 7 percent. By 1950 a population of 5-1/4 million is expected to reside in the region served with water and power by Boulder Dam, as compared with 3,800,000 in 1940.

Low-cost power is already directly contributing new opportunities for livelihood for the rapidly increasing population of the region. It is bringing about a revival of mining operations in Nevada, for example, with the probability that many new developments will be undertaken both in that State and Arizona. (Thirty-six percent of Boulder's power was reserved for the use of these two States.)

Boulder Dam's canyon wall outlets discharging a Niagara of water

Five mining districts in Nevada were without electric service before Boulder power became available. Hundreds of men have been put to work in reopened mines and negotiations are in progress looking to the opening of other workings. The Colorado River Commission of Nevada anticipates that by 1950, mineral and commercial developments in the area will require 60,000 kilowatts or more than five times the present consumption.

At the Boulder City pilot plant of the United States Bureau of Mines, extensive experiments have been made on the use of low-cost power in the reduction of minerals. Manganese deposits in the vicinity of Boulder have been studied with a view to the development of this important strategic mineral held essential to the national defense. Other minerals produced in the district include silver, copper, lead and zinc, platinum, molybdenum, and vanadium. Copper-nickel deposits in the Copper King District are also under investigation.

Harnessing of the Colorado for production of power also is conserving annually in California fields about 10,000,000 barrels of oil, which otherwise would have to be used in electric generation. These examples of the effect of the introduction and distribution of low-cost hydroelectric power generated at Boulder Dam illustrate the importance of this great dam to the Southwest.

Boulder Dam, night

The Benefits Multiplied

In the future remain the incalculable gains to be obtained from the further development of the Colorado River Basin—more water conservation, and more power. Boulder Dam's power revenues are expected to make available under a new law $500,000 annually for the investigation and construction of such projects. The profits to the Southwest and the Nation brought by Boulder Dam will be multiplied, and the horizon of usefulness of Boulder Dam widened still further.

The elimination of destructive floods, the provision of an abundant water supply for irrigation and domestic use, the reduction of damaging silt deposits, the improvement of navigation, the creation of a national playground and a valuable wildlife refuge, the generation of electric energy, the further development of unused resources in the Colorado River Valley—all tell the story of Boulder Dam.

Countless American families know that story first-hand. They have a personal acquaintance with its meaning, and in 1940 they silently joined in the celebration as their radios, powered with Boulder current, brought them the news of Boulder's fourth birthday party. The Columbia Broadcasting System's announcer introduced the ceremony with these words:

"Here's the first stop on our birthday visit to Boulder Dam. We're speaking to you from the visitors' gallery on the Nevada side. Within these walls the spirit and the power of Boulder Damn are almost a living force. Standing here in this room, as long as two city blocks and as high as a 5-story building, we can realize the workings of this project as never before. Behind my back are the waters of Lake Mead . . . 115 miles long and 590 feet deep . . . the largest man-made lake in the world. That tremendous body of water has been tamed . . . turned from its age-old destructive force by those 6-1/2 million tons of concrete that rise above us from our location on the floor of Black Canyon. That water lies smoothly in its man-made bed . . . waiting its chance to take part in the magic of this powerhouse in which we stand, and at the same time serving as a great new recreational paradise which features boating, fishing, swimming, and thousands of square miles of scenic wilderness. . . .

"Perpetual motion may be as impossible as the scientists insist, but here in this generator room, we're watching something which for sheer efficiency and scientific achievement is probably as close to eternal power as anything we'll ever see. Even thousands of words couldn't begin to complete the picture of the vital part which Boulder Dam power, and the water which creates it, play in the life of Southwestern America . . . but here is an impression in sound of one of man's greatest and most complex achievements . . . the sound of the generators of Boulder Dam !"