St. Francis Dam - Planning and Design

Planning and Design

In the early days of Los Angeles, the city's water supply was obtained from the Los Angeles River. Water was brought from the river by way of a series of ditches called zanjas. A private water company, the Los Angeles City Water Company, leased the city's waterworks and provided water to the city. Fred Eaton, superintendent of the Water Company, hired William Mulholland in 1878 as a zanjero (ditch tender). Mulholland proved to be a brilliant employee who after doing his day's work would study textbooks on mathematics, hydraulics, geology and taught himself engineering and geology. Mulholland quickly moved up the ranks of the Water Company and was promoted to Superintendent in 1886 after Eaton left the company when he was elected City Engineer. In 1902, the City of Los Angeles took over the city's water supply, and the city council established the Water Department with Mulholland continuing as Superintendent. The city charter was amended in 1911 and The Water Department was renamed the Bureau of Water Works and Supply, again with Mulholland continuing as Superintendent. He was also named as its chief engineer.

William Mulholland had an enormous capacity for innovation, a penchant for thriftiness and the ability to complete difficult projects on time and on budget. These traits aided the now well self-educated civil engineer in designing and supervising the building of the Los Angeles Aqueduct, which at the time was the longest aqueduct in the world and uses gravity alone to bringing the water 233 miles (380 km) from the Owens Valley to the city of Los Angeles. The enormous project was completed in 1913, on time and under budget, despite several setbacks. Excluding incidents of sabotage by Owens Valley residents in the early years, the aqueduct has operated well throughout its history and is still in operation today.

The rapid growth of Los Angeles demanded a larger water supply, so a series of small reservoirs were built in the 1920s to provide the rapidly expanding city with a water supply in the event of a drought or damage to the aqueduct, but the need for larger reservoirs was obvious.

In the process of designing and building the Los Angeles Aqueduct, Mulholland had considered sections of San Francisquito Canyon as a potential dam site in 1911. Conveniently, the Los Angeles Aqueduct ran along the canyon, and two generating stations in the same canyon used aqueduct water to provide power for Los Angeles. To Mulholland, the location appeared ideal—the reservoir would provide ample water for Los Angeles in the event of a drought or if the aqueduct was damaged by an earthquake or sabotage.