Dam Difficult Work

Building dams during the race to electrify America was not easy. Many of the best dam sites were situated in remote, virtually inaccessible locations. Site topography, available materials, and foundation conditions all presented challenges. Transportation of workers, equipment, and materials to the work site was a daunting task. Motor-powered vehicles did not come into common use until the 1930s.

In the early days of hydroelectricity, when facilities typically were relatively small, teams of draft animals often transported materials and equipment to dam construction sites. For example, shown here are a turbine and generator unit being delivered in 1908 by horse-drawn wagon to the powerhouse of the Bureau of Reclamation’s first hydroelectric project to deliver power commercially, the Strawberry Valley Project in Utah. As the years passed and hydroelectric facilities became larger and larger, this became increasingly difficult.

Strawberry Valley Project Delivery
Source: Library of Congress
Whenever possible, specially constructed rail lines were used to reach construction locations. This often was not practical for remote, mountainous sites. Nonetheless, one railroad constructed to access a dam construction site stands out. In 1912, for the Big Creek project built in California at 5,000-foot elevation in the High Sierras to supply power to Los Angeles 240 miles away, a 56-mile-long supply railroad was built in 157 days. It had 1,100 sharp curves (with curvature up to 60 degrees) and 43 wooden trestles as it wound up the mountain sides to connect with an incline railroad for the final ascent.
Big Creek Project Railroad
Source: Calisphere
Although attempts always were made to utilize materials that were readily available near a construction site, this was not always possible. An extreme example was the San Mateo Canyon Dam, the first dam in the world to be made of concrete. It was completed in 1890 to impound a reservoir to meet San Francisco’s water needs. There was no cement industry in California then, so Portland cement was imported by sea from England and mixed into concrete on site. The dam remains in operation today.
San Mateo Canyon Dam
Source: Library of Congress

Dam construction was very labor intensive, grueling work. Well into the twentieth century, the hand shovel remained the primary earthmoving machine, and construction materials were moved at the construction site by draft animals or human power. The full-swing, 360° revolving steam shovel was developed in 1884, eventually becoming a workhorse for dam construction and easing the load for laborers and draft animals. As previously mentioned, trucks and other motor-powered heavy equipment did not come into common use until the 1930s.

Due to the remote location of most dam construction projects, workers almost never could commute to the work site daily. Construction villages were erected on site by construction contractors, often surrounded by unplanned tent encampments. Thousands of workers toiled on some of these projects and lived in construction villages that were, in effect, full-fledged towns, complete with dormitories and houses for workers, police and fire departments, water treatment and sewage disposal systems, cafeterias, medical treatment facilities, schools, community centers, and recreation facilities. For the construction of Conowingo Dam on the lower Susquehanna River, a construction village was built in 1926 to house a labor force of 3,800 men. When completed, the Conowingo powerplant was the second largest in the world and supplied much needed electricity to nearby Philadelphia. Here is a partial view of the Conowingo Dam construction village:

Conowingo Dam Construction Village
Source: Stone & Webster

Feeding the labor force at these construction villages was a gargantuan task. For example, as the TVA was constructing Fontana Dam in the wilderness of the Great Smoky Mountains, peak employment reached about 5,000 workers. The cafeteria, which seated approximately 1,000 people at one time, served 7,000 meals and packed 2,000 lunches per day during this period.

In these pre-OSHA days, dam construction was exceedingly dangerous work (the Occupational Safety and Health Administration was not formed until 1971). The prevailing working conditions would be unthinkable today. Early versions of hard hats were introduced just after World War I, but the first construction project requiring workers to wear hard hats was the building of Hoover Dam in 1931.

Shown here are workers building Conowingo Dam. Note the crowded conditions, men standing below heavy timbers dangling over their heads, and the complete lack of protective gear. Although no official records were kept of injuries or deaths during construction, the deaths of sixteen laborers have been confirmed.

Conowingo Dam Construction
Source: Stone & Webster
America’s most widely recognized hydroelectric facility, the colossal Hoover Dam, presented colossal construction difficulties. What at the time would be the world’s tallest dam (at 726 feet) was to be shoe-horned into a narrow, nearly vertical canyon situated in an area where summer temperatures regularly reached 120 degrees. The nearest town, Las Vegas, was about 35 miles away. Four diversion tunnels 56 feet in diameter were to be bored through the solid rock canyon walls. Huge amounts of concrete had to be poured to form the dam and powerhouse.

Building Hoover Dam was exceedingly complex. Construction superintendent Frank Crowe observed, “We had 5,000 men in a 4,000-foot canyon. The problem was to set up the sequence of jobs so the workers wouldn’t kill each other off.” To groom the tall canyon walls abutting the dam, high scalers suspended from long ropes brandished 44-pound jackhammers to clear the walls of debris. 98 high scalers were killed doing this treacherous work. Overall, at least 200 men died during the dam’s construction, including a number from heat prostration and carbon monoxide poisoning while the diversion tunnels were being bored.

Hoover High Scalers
Source: Bureau of Reclamation
The rush to completion further increased the difficulty of dam construction projects. Construction crews fought nature and raced the clock before seasonal floods could wash the fruits of their labor downstream. Shown here is a major flash flood as Baker Dam was being built high in the Cascades of Washington State. You can see the flood overrunning the entire construction site and ripping construction materials loose.
Baker Dam Flash Flood
Source: Stone & Webster
Similarly, in northern regions where rivers froze over in the winter, ice floes posed a threat. During the construction of Keokuk Dam across the Mississippi River in Iowa, the river froze during the winter, with ice that was 2 to 3 feet thick. As the ice broke up in March 1912, huge floes careened downstream and battered the partially completed dam.
Keokuk Dam Ice Jam
Source: Mississippi River Power Company
Another factor creating immense pressure to rush the completion of hydroelectric dam construction projects was the call to begin generating revenue from the sale of electricity as soon as possible to offset the large cost of these projects. The Keokuk project manager frequently pointed out that interest expense alone on that project’s financing was more than three thousand dollars a day (over $100,000 a day in today’s dollars).

All in all, building the dams that restructured our landscape and electrified America was an amazing feat. The work was difficult and dangerous, but men flocked to the opportunity, wanting to be part of something big, something that mattered. The engineers crafting various hydroelectric projects often received little public attention. Also lacking public attention were the hundreds of thousands of workers who actually built the dams and toiled namelessly. Most of them remain faceless in the pages of history. Yet the public has long marveled at their achievements.

Robert L. Underwood
May 14, 2026