Mulholland’s St. Francis Dam Collapse Tragedy Claims Over 400 Lives, Sparks Reform

William Mulholland, the self-taught head of Los Angeles’s water department, had pushed the St. Francis Dam into service in 1926 without independent geological review, building it on a known landslide of mica schist and raising its height during construction. After a supervisor reported muddy seepage on March 12, 1928, the dam collapsed at 11:57 p.m., sending a ten-story wall of water down the Santa Clara River, destroying cabins, a hydroelectric plant, and a bridge, and killing more than 400 people, including the man who first warned Mulholland.

The disaster’s aftermath saw Mulholland testify that he had never imagined the dam to be unsafe, while the coroner’s jury attributed the failure to the poor rock foundation and cleared him of criminal liability. The tragedy led to tighter state dam-construction laws and the eventual removal of the dam’s remnants. Mulholland resigned seven months later and died in 1935, his legacy largely remembered for the aqueduct rather than the dam collapse.