Inside Hoover Dam

A motorist parked his car on the roadway atop Hoover Dam hopped out rushed to the wall and looked over the downstream side of the giant concrete barrier to the Colorado River 600 feet below. “Wow!” he exclaimed jumped back into his car and drove on.

Perhaps “wow!” best describes this pioneer Reclamation multipurpose dam which straddles the mighty river between Nevada and Arizona. If the hurried motorist had spared the short time it takes to go through the dam, he would have been “wowed” even more.

This word and picture tour of Hoover Dam is for that hurried motorist and others who have yet to see the inside of Hoover Dam one of the American Society of Civil Engineers' Seven Modern Civil Engineering Wonders. And those millions who have been inside Hoover Dam will recall pleasant memories of their tour on these pages.

The Bureau of Reclamation has built larger but not higher dams since 726-foot tall Hoover Dam corralled the Colorado River nearly three decades ago. But it has not constructed a more popular dam. On the average summer day atop Hoover Dam you can count cars from every one of the nation's fifty states, and from many foreign countries. About three times more people tour Hoover Dam than this country's next most popular dam.

Commissioner of Reclamation Floyd E. Dominy thinks Hoover Dam will likely continue to be Reclamation's most visited project. He proudly points it out as a Reclamation showplace an example of what happens in multipurpose water benefits when man harnesses a mighty river.

Glen Canyon Dam 370 miles upstream on the Colorado River in northern Arizona promises to give Hoover Dam a close race in the number of visitors when it is opened to the public after the powerplant has been completed.

Since guided tours of Hoover Dam were begun January 1, 1937, 91/2 million visitors have seen the wonders inside the dam and powerplant. And just how many are 91/2 million people? Well, if they all joined hands they would form a circle within the continental United States which would touch the Pacific and Atlantic coasts and the Canadian and Mexican borders.

Late this summer, Boulder Canyon Project Manager Dee O. Towne, who supervises Hoover Dam for the Bureau of Reclamation, will greet the ten millionth visitor on the guided tour. You could be this ten millionth visitor if you are there at the right time.

Imagine it is a sunny day in late summer atop Hoover Dam a week day a Saturday or perhaps a Sunday. You have bought your ticket and are awaiting in line under the concrete canopy at the Nevada elevator tower where tours begin. The tower supervisor has announced over the public address system that the next tour will be going down the elevator within a few minutes. The Project Manager walks up to you and introduces himself. "Welcome to Hoover Dam! You are our ten millionth visitor."

You will be just as surprised as were the other nine people who toured Hoover Dam on previous millionth milestones. Each had little idea he or she would be historically recorded on the dam's guest register and in the Boulder Canyon Project reports.

The one millionth visitor toured Hoover Dam in 1940 without special recognition. But each million mark has been noted since resumption of tours in 1945 after World War II.

Each millionth visitor is counted about every two years. John Sheridan of San Francisco toured Hoover Dam October 13, 1962, as the nine millionth visitor. Others included Miss Maria Krusoff, Oak Park, Illinois, September 29, 1946, two millionth; Mrs. K. E. Jung, Newport, Rhode Island, May 25, 1949, three millionth; Mrs. William C. Carr, Los Angeles, October 16, 1951, four millionth; Mrs. Henry Victor, Santa Rosa, California, April 2, 1954, five millionth; Miss Clara Hoffman, Bell, California, June 30, 1956, six millionth; Leonard Goff, Morrill, Nebraska, August 7, 1958, seven millionth; and Wayne Hawke, Albany Oregon, September 13, 1960, eight millionth.

The number of people taking the guided tour of Hoover Dam each year has jumped from 298,553 in 1937 to approximately 600,000 in 1963. The numberof visitors increases every year. The National Park Service has recorded approximately fifty million visitors to its Lake Mead National Recreation Area since it was established in 1936, nearly a fifth of whom toured Hoover Dam.

The tour requiring thirty-five minutes is one of America's biggest values for thirty cents. This fee defrays the cost of the guides' salaries and other tour expenses. Children under twelve, military personnel in uniform, school and youth groups organized under adult supervision are admitted free. Tour hours are from 7:00 a.m. to 8:00 p.m. from Memorial Day through Labor Day, and 8:00 a.m. to 5:00 p.m. the remainder of the year.

During the busy vacation season from Memorial Day week through Labor Day week, Reclamation tour leaders conduct up to 3,600 visitors a day through the dam and powerplant. Steady streams of visitors in groups up to sixty-eight for each tour travel up and down the Hoover Dam elevators continuously each group on the heels of another. The average tour group, however, is about forty-four people, or two elevator loads.

In the fall, winter, and spring months, when schools are in session, the flow of visitors slows to a daily average of about 1,089. Tour groups normally go through the dam and powerplant at twenty minute intervals.

Eighteen tour leaders, several of whom helped build the dam, including supervisors and a ticket cashier, work regularly on the Hoover Dam guide staff. During the heavy summer months, nine temporary tour leaders, usually teachers and college students, are added to the staff to take care of the seasonal surge of visitors.

As time for each tour rolls around, the guide supervisor on duty admits an elevator load of twenty-two people through the tower. He introduces them to their guide and they are on their way. The elevator, after depositing the guide and the first half of his party in the ceramic-tiled inspection gallery or tunnel in the heart of the dam, returns to the top for the remainder. With his full party in tow, the guide begins his tour of the dam and powerplant.

These guides tell the same Reclamation story 365 days a year, including Sundays and holidays, to Hoover Dam visitors. But each tells it in his own refreshing style - in his own words. His is a thrilling story with authentic answers to the thousands of visitors' questions.

Some questions bring smiles to the guides' faces. Tour leaders are often asked: "Where do you store the coal for the powerplant?" "Where do you store the electricity?" "Why is the water higher on one side of the dam than on the other?" "Which way does the water flow in the river?" "Was there always a lake there?" "How many buckets of water does it take to fill the lake?" and so on.

Two women were watching a boat on Lake Mead from atop the dam. Moments later, they walked to the downstream side of the dam and saw a similar boat on the river. "Well, can you beat that!" one exclaimed. "That boat we saw on the lake has gone through one of the tunnels and is now down there on the river."

A guide was attempting to explain to a woman why the water is higher on one side of the dam than on the other. She interrupted him, "Young man," she said, "Don't try to confuse me. I know that water seeks its own level. The water should be the same height on both sides."

But, all joking aside, let us return to our makebelieve world on this projected day late in the summer of 1964. Mr. Towne will conduct you, the ten millionth visitor, on a red-carpet tour of Hoover Dam. Your party, including members of your family, and the reception committee of Reclamation, National Park Service, and Chamber of Commerce officials will accompany you.

In the lobby of the elevator tower you sign the guest register in which the names of other millionth visitors, Presidents, Kings, princes and other dignitaries appear. Then you enter the elevator and drop into the heart of Hoover Dam. The recorded voice of Mack Townsend now a retired Hoover Dam guide tells you in the elevator that you are descending 528 feet into the dam a distance equal to forty-four stories in an office building. The elevator makes the trip in one minute and fifteen seconds. You pass doors to inspection tunnels inside the dam, numbered from one at the top of the dam to six at the end of the elevator shaft. When you step off the elevator, you are still 199 feet above the base of the dam and about 190 feet below the low water level of Lake Mead. The dam 660 feet thick at its base is 457 feet thick at this point. The water in Lake Mead is only 107 feet from you on the opposite side of the concrete wall which you face upon leaving the elevator.

As your Reclamation host leads you through the beautiful ceramic-tiled tunnel over terrazzo floors to the powerhouse, he tells you more about Hoover Dam and the Reclamation program which was established by the Congress in 1902.

Hoover Dam is the key structure of the Boulder Canyon Project, authorized by the Congress in 1928, and constructed during the first half of the 1930's. Hoover Dam first of the great Reclamation multipurpose developments controlled the Colorado River for the first time. The project also includes the AllAmerican Canal System in southern California.

You are informed that Hoover Dam is fulfilling the multipurposes for which it was designed and constructed. These are flood control, water storage and regulation for irrigation, domestic and industrial uses, and generation of hydroelectric energy. Other benefits include recreation, fish and wildlife, and silt control.

As you walk along the tunnel, Mr. Towne describes to you the Indian basketry and pottery designs inlaid in the terrazzo floor.Next, you go by elevator from the balcony on the fifth floor of the powerhouse to the third or generator floor. Visitors on the regular guided tours walk down a flight of steps to this floor instead of taking the elevator, which is too small to accommodate a large number of people. Those unable to walk down or up the steps due to health and other reasons, of course, are invited to ride the elevator. But you are the mythical ten millionth visitor, so you will ride the elevator, good health or bad.

At the end of the passageway, you enter the fifth floor of the U-shaped powerplant at the foot of the dam and walk onto the balcony overlooking the Nevada wing of the powerplant. Here, you look out over the long row of eight giant hydroelectric generators. Those lighted on top are in operation at the moment. The generators are called into service during the day and night as the demand rises in southern Nevada, southern California and Arizona. The Hoover Powerplant is used to supply the peak loads in the various market areas.

The Hoover Powerplant has twin wings, one in Nevada and the other in Arizona. The Nevada wing has seven units rated at 82,500 kilowatts, and one at 95,000 kilowatts, while the Arizona wing has seven 82,500 kilowatt units, one 40,000 kilowatt unit, and one 50,000 kilowatt unit. Each wing has a Pelton horizontal water wheel station service generator rated at 2,400 kilowatts. These supply electrical power for the dam and powerplant. The plant's seventeen large generating units are vertical with reaction turbines.

On the balcony, the Project Manager describes the powerplant to you over a public address system from a booth. Several small speakers mounted above the hand safety railing make it possible for you to hear his voice above the roar of the generating units. Guides use this public address system in lecturing to their groups.

Mr. Towne leads you past one of the station service generators along the row of large generators to the end of the Nevada powerhouse wing. Each of the plant's two wings could accommodate two football fields laid end to end. You pause at several generators and learn how the units work, and what those various dials and meters on the front mean.

At the end of the generator room, you pass through a door to the outside ramp. There you are deep in Black Canyon dwarfed by the tremendous size of the dam and gorge. You look up hundreds of feet to the top of the dam from which the hurried motorist gazed down upon the structure and the river and said “wow.” On the ramp, you see the canyon wall access tunnels, the 150-ton overhead cableway which lowered much of the material and equipment for Hoover Dam and its powerplant, the canyon wall outlet needle valves and other features of the dam and powerplant. You peer over the protective wall into the 40-foot deep emerald green water in the tailrace or river. The water gushes and bubbles up in white and green foam as it comes from the turbine discharge or draft tubes after it has spun the turbines and their generators to produce electrical energy. This water under the powerful pressure of 225 pounds per square inch flows from Lake Mead above through the powerplant's four 30-foot diameter penstocks to the turbines.

At the downstream end of the ramp, you are fascinated by the large rainbow trout in the shallow water on the canyon wall rocks. These fish thrive in the cold water released from deep in Lake Mead through the penstock system to the river below the dam. They test the angler's skill in the headwaters of Lake Mohave accessible to fishermen from Willow Beach, twelve miles below the dam on the Arizona side.

Next, your Reclamation host leads you down the outside ramp along the row of huge transformers. These transformers step up the electrical energy from 16,500 volts as it comes from each of the large generators to as high as 287,500 volts for transmission to Los Angeles and other southwest markets.

Crossing the ramp over the tailrace at the bottom of the U-shaped powerhouse, you enter the Arizona wing of the powerplant. Here you see virtually the same that you saw on the Nevada side. You cross the Arizona wing past the second small station service generator and enter an unlined rock tunnel in the canyon wall, which is perpendicular to the river. The passageway takes you to the lower penstock or one of the four original diversion tunnels, which generally run parallel to the river. Drilled and blasted out of the hard volcanic rock of the canyon, the access tunnel needs no artificial support. Along the tunnel walls you see the drill marks and grout holes through which liquid concrete under high pressure was pumped to seal off the cracks and stop seepage from springs.

Aided by diagrams and pictures of Hoover Dam and Powerplant, the Project Manager takes you step by step through the various phases of construction. He cites interesting facts about the penstock system that the boiler plate from which the big pipes were rolled is 23/4 inches thick, and that the rivets weigh 13 pounds each. These pipes are larger than the Holland Tunnel under the Hudson River at New York City, and can easily carry a railroad train or two lanes of highway traffic. There are almost four miles of these pipes in the canyon walls.

Topography of area explained

Hoover Dam has far-reaching impact upon life in the Pacific Southwest, you are told. After leaving Hoover Dam, water is reused at other Reclamation hydroelectric powerplants downstream to generate hydroelectric power. This water which has already served several purposes -is diverted to farms, homes and factories in the Pacific Southwest. Flood waters stored and regulated by Reclamation dams in the lower Colorado River basin last year supplied part of the domestic and industrial needs of 10 million residents in the Pacific Southwest; irrigated nearly 900,000 acres of land in this country, which produced crops valued at about $291 million with a per acre average of $348.50; and generated over five billion kilowatthours of hydroelectric energy for a gross power revenue to the Federal Government of $17-1/3 million.

Hoover Dam and Powerplant cost approximately $175 million. To date, the project has returned $127 million in interest and principal to the Federal Treasury. The cost of the project less $25 million allocated to flood control will have been substantially repaid to the Federal Treasury at three percent interest largely through the sale of hydroelectric energy by the year 1987. The flood control allocation will be repaid after 1987 at the discretion of the Congress.

Back in the Arizona wing of the powerplant, you go down the elevator to the second floor or the turbine gallery to view the bright shiny spinning steel shafts of the generating units. These are sixty-five feet long, thirtyeight inches in diameter, and turn at a rate of 180 revolutions per minute. They connect the turbine wheel with the moving part or the rotor of the generator above to produce electricity. The rotating weight of each generating unit is about 800 tons.

As you step back onto the elevator, Mr. Towne takes you to the eighth floor, where you pass through control rooms of the Southern California Edison Company and the City of Los Angeles, Department of Water and Power. The City of Los Angeles and Southern California Edison Company operate and maintain the generating units as agents of the Federal Government for the nine Hoover Dam power allottees or contractors. You observe panel boards of colored lights and diagrams indicating to the operators where the transmission lines and switchyards are located, which switches are opened and closed, and other information. Operators are reading the many meters along the upright panels and marking their recordings on sheets of paper attached to clipboards. The control rooms are the "brain" of the Hoover Power-plant and its transmission and interconnecting systems. The generating units and transmission system switches may be be remotely operated from the control room manually. These facilities also are controlled by automatic devices. For example, last summer a storm damaged a substation in southern California. The generating units in the Hoover Dam which supply power to the transmission lines were automatically disconnected.

This ends your special tour of Hoover Dam and its powerplant, and you go back down the powerhouse elevator to the fifth floor. You walk along the balcony overlooking the Arizona generators. Your view here is similar to that on the Nevada side of the river. You return to the top of the dam via another ceramic-tiled tunnel like the one on the Nevada side, and up another elevator which is a twin to the other side. On the Arizona elevator going up, a recorded voice invites you to visit the Lake Mead National Recreation Area administered by the National Park Service, a Department of the Interior sister agency to the Bureau of Reclamation. The recording points out some of the interesting places around the lake such as Boulder Beach on the Nevada side, Willow Beach and Katherine Wash on the Arizona shore of Lake Mohave below Hoover Dam. Lake Mohave was created by Davis Dam, an earth and rockfill structure on the Colorado River sixtyseven miles downstream.

One of the most important stops on the Hoover Dam tour is the Exhibit Building against the canyon wall at the Nevada end of the dam. This building, open without charge to the public, contains a scale model of one of the generating units, and a large topographic model of the Colorado River basin. The basin topographic or relief model is in a small auditorium with elevated seats. Visitors view the model as they listen to a recorded eight-minute lecture. Spotlights automatically highlight each feature on the model as the lecturer discusses it. When your visit to the exhibit building has been completed, your party will leave the dam for a National Park Service boat trip trip on Lake Mead, with Superintendent Charles Richey as host, and other festivities planned for you by the southern Nevada reception committee. These include a night of free lodging, a dinner, and souvenirs for you and your party.

The pictures taken by a Bureau of Reclamation photographer showing you all along the tour route will be placed in an album with your name imprinted in gold. This album will be presented to you later by Mr. Towne as a memento of your visit to Hoover Dam.

Before you leave the area, you will see the Department of the Interior's official film, THE STORY OF HOOVER DAM, shown continuously daily, free of charge, at the Visitors Bureau, a private business firm, in downtown Boulder City. This film is a "must" for all visitors to the area.

Now, you see what a fine time you would have if you are actually Hoover Dam's ten millionth visitor. But even if you are not the lucky person, a grand tour of this Bureau of Reclamation marvel in Black Canyon on the Colorado River awaits you.