The Collapse of the St. Francis Dam: Killer Water

(NOTE: This is an excerpt. To read my full account of the St. Francis disaster - including Lake Hollywood, the sister to St. Francis located in Hollywood – I invite you to get a copy of my book, “Our World of Water.”)

St. Francis before its collapse. Colorized image.

At five minutes to midnight, on Thursday, March 12th, 1928, the towns of Santa Paula, Newhall, Piru and Fillmore, located in Ventura County, north of Los Angeles, were sequestered from harm, residents asleep in their warm beds. Less than three minutes later, all hell would break loose and more than 600 people would be dead from the single worst engineering disaster of the 20th Century in the United States. Though it has become a footnote in California history, the St. Francis Dam disaster is a tragedy of unparalleled proportions. Why the dam was built and why it failed is a complex story of greed, vision, money, and dreams of the future. But fundamentally it’s about water.

William Mulholland. Photo Water & Power Assoc

When Los Angeles began to grow, William Mulholland, the chief engineer of the Department of Water and Power (DWP), envisioned Los Angeles as a utopia for millions of people. But Los Angeles would soon run out of the one thing that made its existence possible in the first place - water. So where does one find vast quantities of water when one lives in a semi-dessert environment? The Owens Valley is a rural farming community, 250 miles north of Los Angeles and it held massive amounts of water, fresh from the snow packs of the Sierra Nevada Mountain range, which could provide the burgeoning metropolis with every drop it needed. Los Angeles began to surreptitiously buy water and land rights in the Owens Valley and, even today, L. A. is the largest landowner in the area.

In 1910 Mulholland designed and constructed an aqueduct 230 miles long, using gravity flow over mountains and across desserts, one of the great engineering achievements of the early 20th Century. Owens Valley farmers, angered at being lied to saw their water levels decrease dramatically. Many farmers were wiped out. I have been to Owens and it is an incredibly sad sight. What was once a fertile valley is a dry ghost town.

Mulholland believed that a series of dams and reservoirs, closer to L.A. would be the safe bet in case emergency water was needed. The 13 billion gallon capacity St. Francis Dam was constructed in a narrow canyon north of Santa Clarita near present day Magic Mountain. Since Los Angeles continued to grow much faster than anyone anticipated, when the Owens Valley began to run dry within a few years, L.A. secured water from Mono Lake, north of Owens Valley; then the Colorado River in Nevada; then the Feather River near Sacramento. It’s thirst was, and still is, insatiable.

After the failure.

Construction of the St. Francis began in April 1924. In July of that year, the original dam height of 184 feet was extended 10 vertical feet in order to expand its holding capacity. One year later another ten vertical feet was added. Raising the dam 20 feet allowed more storage capacity, but what was overlooked was widening its base to be commensurate with its new height. Known as “hydraulic uplift,” the base of the dam actually raised up slightly prior to its demise due to its inherent instability. Additionally the rock the dam was anchored to, a flaky metamorphic rock, was not fully understood by the engineers at the time, nor did they know the mountain was part of an ancient landslide and was also inherently unstable - it was becoming saturated with water.

Only the main section of the dam remained. Notice the two people, lower right

At 11:57 p.m., the St. Francis Dam collapsed. What was once a life-giving force turned into death itself and made worse when it merged with the Santa Clara River. The initial wall of water was 200 feet high. Of the 70 people that lived just below the dam, only three survived. By the time the water hit Castaic Junction, near present day Six Flags Magic Mountain off Interstate 5, the water was 75 feet high, and Santa Paula faced a torrent still 25 feet high with trees and broken houses acting like battering rams obliterating anything in its way. The path of destruction was 54 miles long. Five and a half hours after the dam collapsed, the water merged with the Pacific Ocean near Ventura Harbor.

600 people died, many of them Mexican farm workers living at camps located near the river. Poor immigrant workers don’t land on the front page of major newspapers, not in 1928. But they died - by the hundreds, cattle too. Livestock, cars, roads, power lines, bridges, rail track, farms, all were washed to the ocean or covered in a blanket of mud, debris and wreckage nearly 30 feet thick. Some bodies were found weeks later in isolated canyons along the Santa Clara River. There were bodies recovered 200 miles away near San Diego, and some bodies have never been found. Men, women and children were obliterated in the middle of the night, in their beds. Some fought the torrent of water, only to drown or be crushed by the fast moving debris. Perhaps mercifully so, some families died instantaneously, family pets being the only survivors; mute witnesses to the unthinkable. 

The numbers are staggering: 1,200 homes demolished, 24,000 acres of fertile land destroyed, 11,000 acres of crops laid waste, 140,000 trees uprooted or badly damaged. 3,000 volunteers searched for bodies.

After inquires and reports, dam safety legislation changed. Prior to the St. Francis, there was little dam construction oversight. Two days after St. Francis failed the federal government required all dams to be inspected. California mandated professional registration for engineers, soil compaction tests and a greater understanding of hydraulic uplift, which became the model for the rest of the country, but this was a painful lesson.

Catherine Mulholland

I interviewed Catherine Mulholland, granddaughter of William Mulholland who built the St. Francis, shortly before her death. Her words were profound and have resonated with me to this day, and sum up water and power. “By now we know that Homo sapiens have plundered the earth. We've dislodged, displaced and removed forests and oceans. We've flourished and also suffered. When you move water, things get destroyed in the process."

WATCH my short video on location at the St. Francis Dam site:

"The St. Francis Dam Collapse: A Visit To The Dam Site"

Portions of the dam still exist today: this piece being part of the front face of the dam.