Skip to main content
U.S. flag

An official website of the United States government

St Francis Dam Disaster

March 2024 (approx.)

Detailed Description

Image courtesy of Los Angeles Times public archives. Acquired 3/2024


The St. Francis Dam Disaster, which occurred on March 12-13, 1928, was one of the worst civil engineering failures in American history. The St. Francis Dam was a concrete gravity-arch dam built to create a reservoir in San Francisquito Canyon, northwest of Los Angeles, California. It was designed and built by William Mulholland, the chief engineer of the Los Angeles Department of Water and Power.

The disaster happened when the dam collapsed, sending approximately 12.4 billion gallons of water rushing down the canyon. The wall of water traveled at speeds of up to 18 miles per hour and reached a height of 140 feet in some places. The floodwaters devastated the communities downstream, including the towns of Santa Paula, Fillmore, and parts of Ventura. The flood caused the deaths of at least 431 people, although the exact number is unknown due to the difficulty of counting victims in the aftermath.

The exact cause of the dam's failure is still debated. Some theories suggest that the dam's design or construction flaws played a role, while others point to the geology of the canyon or the high levels of water in the reservoir at the time of the collapse. Regardless of the cause, the St. Francis Dam Disaster remains a tragic event in American history, highlighting the importance of proper engineering and oversight in infrastructure projects.


Public Domain.