CityDig: A Faulty Dam Led to the Deadliest Disaster in L.A. History

This 1963 map details the path of floodwater that resulted from the collapse of William Mulholland’s St. Francis Dam
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Route of the St. Francis Dam Flood From the book by Charles F. Outland and Arthur H. Clark, cartographer D.H. Baker
Route of the St. Francis Dam Flood From the book by Charles F. Outland and Arthur H. Clark, cartographer D.H. Baker, 1963

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This meticulously hand-drawn map quietly depicts the devastation of the worst civil engineering failure of the Twentieth Century. On the morning of March 13, 1928, the front page of the Los Angeles Times declared “200 DEAD, 300 MISSING, $7 MILLION LOSS.” The St. Francis Dam in San Francisquito Canyon had failed, and the resulting flood ultimately took the lives of 400 to 600 people and destroyed over 1,200 homes. It also wrecked the sterling reputation of the dam’s chief engineer, William Mulholland, who, until that fateful night, was as beloved an Angeleno as ever lived.

The St. Francis reservoir was one of a string of reservoirs built to supply Los Angeles with water if the aqueduct system failed. Behind the largest arch-supported dam in the world, it held 12 billion gallons of water—enough to sustain the city for an entire year. As with the Titanic, the engineers who designed the magnificent dam assumed their grand feat was immune to problems. On May 13, 1926, Mulholland opened the gate to release the first 70 million gallons of water into the reservoir, and for two years, the dam held.

Mulholland was called back to the site on March 12, 1928, after dam keeper Tony Harnischfeger detected a leak on the west abutment.  The structure, however, seemed sound to Mulholland, who returned to Los Angeles confident that the supposed leak was just muddy water from a nearby construction project. At 11:58 that night, the middle of the dam collapsed. The reservoir’s 12 billion gallons of water rushed down the canyon at 18 miles an hour, knocking out power along the way. The flood swept through Castaic, Saugus, Fillmore, Santa Paula, and Saticoy. By the time sleeping communities got warning of the flood, it was 1:20 a.m.—too late for the hundreds already drowned in the rushing waters. The force of the deluge was so great that debris and bodies were washed 55 miles clear out to the sea. Some victims were found as far away as Oxnard in Ventura County. It was the second greatest loss of life in California history, after the 1906 San Francisco fire.

The heartbroken William Mulholland willingly took the heat for the catastrophe. “Don’t blame anyone else, you just fasten it on me,” he said at the hearing. “If there was an error in human judgment, I was the human, and I won’t try to fasten it on anyone else. On occasion like this, I envy the dead.” The citizens of Los Angeles who had worshipped Mulholland when he brought water to the desperate city in 1913 now turned on him with a fury. The story of the St. Francis dam and its ill-fated placement at San Francisquito is discussed to this day, but it seems its lessons are lost on the current generation. Estimates suggest that as many as 4,400 dams today are inadequately maintained and in extremely poor condition. With big earthquakes ahead, that should be cause for concern.


Los Angeles Public Library map librarian Glen Creason shares a map from the Central Library’s collection at CityThink each week.

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