Eighty-five years ago, the second worst disaster in California history occurred just minutes from downtown Santa Clarita.

Known as the St. Francis Dam disaster, the failure of the massive dam in the remote San Francisquito Canyon area of Saugus occurred at 11:57:30 p.m. on March 12, 1928, a time pegged to the loss of electricity from the Southern California Edison transmission lines located 90 feet above the dam’s eastern abutment.

Some 12.5 billion gallons of water poured down the narrow canyon in a 140-foot-high wall of water, sweeping more than 500 men, women and children to their deaths on its way to the Pacific Ocean.

In California’s recorded history, only the 1906 San Francisco earthquake killed more people.

The lake behind the dam was three miles long and took an hour to drain after the dam’s collapse. That collapse took just 90 seconds.

As the flood carved out a path to the sea, it lay waste to Castaic Junction, Piru, Fillmore, Santa Paula and Saticoy before emptying into the Pacific Ocean, more than 50 miles away near Ventura.

When the flood reached the ocean, 5 1/2 hours after the dam crumbled, it was reported by observers to be 15 feet high and three-quarters of a mile wide.

The St. Francis Dam was the brainchild of William Mulholland, the manager and chief engineer of the Los Angeles Department of Water and Power.

The St. Francis Dam was built from 1924 to 1926 and was originally designed to tower 185 feet above the canyon floor. However, the dam was raised twice after construction began, giving it a final height of 205 feet. It was filled to capacity on March 7, just five days before it collapsed.

Mulholland had designed the aqueduct from the Owens Valley that brought water to Los Angeles. He built the dam to hold a year’s supply of water for the city of Los Angeles.

In the aftermath of the disaster, Mulholland accepted blame for the failure of the dam.

Many theories have surfaced over the years to account for the dam’s failure.

Some thought Owens Valley farmers blew up the dam in retaliation for “stealing” their water.

Other theories held that the dam was built of inferior building materials and on “slippery rock” — The Pelona schist on the east side of the canyon.

J. David Rogers, a civil engineer, geologist and professor at the Missouri University of Science and Technology, has spent years studying the St. Francis Dam.

He suggests the failure of the dam was the result of its construction at the site of an ancient landslide — information geologists of the 1920s would not have known — coupled with the concept of “hydraulic uplift.”

In a scholarly paper about the dam, Rogers wrote: “Probably the greatest single factor that could be pointed to was the decision to heighten the dam a second time. Aside from the geologic shortcomings, all of the structural analyses predicted overstressed conditions when the reservoir pool rose within seven to 10 feet of crest.

“Had the dam not been heightened that last 10 feet, it might have survived.”

As a result of the St. Francis Dam disaster the California Legislature created a dam safety program in 1929.

Today, visitors to the site often walk right past crumbling pieces of the concrete dam, unaware they can reach out and touch a piece of history.

San Francisquito Canyon Road previously ran directly through the dam site, but it sustained heavy storm damage in 2005 and the road was rebuilt, routing it away from the remains of the dam.

The site of the disaster is registered as California Historical Landmark No. 919.

mbuttelman@signalscv.com
661-287-5590