Theodore Roosevelt Dam: A Century of Power
Completed one year before Arizona’s statehood, the Theodore Roosevelt Dam helped grow the Phoenix area. Not only did it ensure a steady, manageable water supply for an emerging agricultural zone, it supplied power to rural households nearly ten years before the National Rural Electrification Act brought power to the rest of rural America. As the dam tamed the waters of the Salt River, it electrified Phoenix as a modern city with a bright future. The dam’s promise is immortalized by its appearance on the Arizona State Seal.
Started in 1905, the Theodore Roosevelt Dam was the first project undertaken by the U.S. Reclamation Service (now called the Bureau of Reclamation). It was Reclamation’s first hydroelectric project and last masonry dam. Standing 280 feet high and spanning 723 feet across the Salt River Canyon, it was the tallest masonry dam in the world when it was completed in 1911.
The story of Phoenix begins with water—about 2,000 years ago. The Hohokam Indians farmed the Salt River Valley for almost 1,500 years, building an advanced network of irrigation canals. In 1867, 400 years after the Hohokam left, a prospector named Jack Swilling opened an irrigation and canal company based on the ruins of the Hohokam canals. “Swilling’s Ditch” irrigated crops which went to feed the gold prospectors at the Vulture Mine in Wickenburg. Irrigation canals quickly became popular, and over the next 40 years the Salt River Valley blossomed into an agricultural community.
The 200-mile Salt River is one of Arizona’s key riparian areas. Like many waterways, its levels would swell and recede, sometimes flooding and sometimes running low. Growers wished to dam the river to regulate water flow and to create a reservoir for water storage. But dams are an expensive operation. The federal government offered a brand-new solution.
President Theodore Roosevelt, a naturalist and advocate for the conservation of soil and water, signed the National Reclamation Act and created the U.S. Reclamation Service in 1902 to facilitate water management across the country. Known today as the Bureau of Reclamation, the agency’s projects, including the Yuma Project in 1903, were integral to the settlement of the American west. Read more about the history of Reclamation in Arizona.
The Roosevelt Dam was the first major project of this newly formed agency. Growers in the Phoenix area formed the Salt River Valley Water Users’ Association and offered their land as collateral to finance the project. In 1905, dam construction began at narrow canyon 76 miles east of Phoenix.
The path to completion was arduous. Floods would knock out construction and wash away materials. Initially estimated at two years, construction dragged three times longer than originally proposed. After 344,000 cubic yards of masonry stone and a sub-equal volume of cement assured the dam’s sturdiness, the structure created Roosevelt Lake, at the time the world’s largest human-made lake. President Roosevelt himself made it over the Apache Trail to dedicate the dam on March 18, 1911.
Hydroelectric Power at Roosevelt Dam
By the turn of the century, hydroelectricity was fairly common in dams in the northeast. Members of the Salt River Valley Water Users’ Association saw hydroelectric power as a way to offset costs of the dam. Dam plans included a hydroelectric power plant, and several small hydroelectric generators installed prior to construction to run equipment and lift the masonry to build the dam. The 4,500 kW power plant was one of the first large power facilities constructed by the federal government.
On August 1, 1909—over a year before the dam was completed and three years before Arizona’s statehood—hydroelectric power generated at the dam was delivered to Phoenix by way of a brand new transmission line. Three months later, a brand new substation for Pacific Gas and Electric Company was receiving the hydroelectric energy.
Rural electricity was still so rare that transmission lines were a true novelty. Children made a game out of climbing the poles and grabbing the wires. When the line was about to be energized, Reclamation warned, "The Reclamation Service gives warning to everybody between here and Theodore Roosevelt, that the power is likely to be turned on. The warning is now given that there is danger and plenty of it, and if the warning is not heeded somebody may be killed. Parents will do well to impress these facts on their children."
At first, surplus power generated by the dam’s hydroelectric plant only served about half a dozen customers, but that number quickly grew. In 1912, the dam supplied power to a copper company in Miami, Arizona. By 1928, hydroelectric dams built on the Salt River at Horse Mesa, Mormon Flat and Stewart Mountain helped energize the Valley’s rural areas nearly 10 years before the passage of the National Rural Electrification Act.
In 1950, the Salt River Valley Water Users’ Association merged with the Salt River Power District to become the Salt River Project (SRP). Today the Salt River Project supplies power to about 930,000 customers. Generation capacity at Theodore Roosevelt Dam has increased to 36 mW. Hydropower from the Salt River generators are still part of SRP’s renewable energy portfolio.