The St. Francis dam failed 90 years ago this March, spilling 13 billion gallons of water. Matilija Dam in Ojai has for years been scheduled for removal. Montecito had no physical dam, but the release of torrential rain and mud acted like one had burst. It is water that inexorably links these places together. Water is no respecter of persons, animals, geography or economic status, yet it is a force that defines us, and what occasionally defeats us.

Failure at St. Francis

Thursday, March 12, 1928. William Mulholland, director of the powerful Los Angeles Department of Water and Power, was asleep in his Hollywood home. Throughout Santa Paula, Newhall, Piru and Fillmore in Ventura County, residents were also asleep in their beds. At three minutes to midnight, hell was unleashed as the St. Francis Dam failed and nearly 500 people would be dead in a matter of a few hours. The event was the single worst engineering disaster of the 20th century in the United States. Though it has become a footnote in Ventura County’s history, the St. Francis is a tragedy of epic proportions. Why the dam was built and why it failed is a complex story of greed, noble intent and dreams of the future. Primarily, however, it’s about water.

Author Michael Cervin at the remains of the St. Francis dam near Magic Mountain.

Early Los Angeles needed two things to prosper: people and water. Therefore, construction of the St. Francis Dam, a water retention facility for Los Angeles, began in April 1924. Three months later the original height of the dam — 184 feet — was extended 10 vertical feet in order to expand its capacity. One year later another 10 vertical feet was added. Raising the dam 20 feet allowed more storage capacity but what was disregarded was widening its base to be commensurate with its new height. Known as “hydraulic uplift,” the base of the dam raised up about .13 feet prior to its collapse, according to J. David Rogers, Ph. D., professor at Missouri University of Science & Technology, who spent three decades researching the dam for his book The St. Francis Dam Failure and Its Impact on American Civil Engineering. In laymen’s terms the dam was top-heavy.

“It was a seriously overstressed structure,” Rogers told the VCReporter. Additionally, the rock the dam was anchored to, a flaky metamorphic rock, was part of an ancient landslide and was consequently inherently unstable. The technology did not exist in the 1920s to know that the rock was faulty — it was becoming saturated with water.

Ironically, on March 11, the day before the failure, Mulholland himself inspected the dam at about 10:30 in the morning, looking specifically at a large crack — visible after the collapse — which was pouring out two cubic feet of water per second. When someone asked him about the water his reply was, “Typical of concrete dams,” then pronounced it secure.

“St. Francis had so many shortcomings,” Rogers said. “The hydrostatic pressure was the most likely culprit in the dam’s demise.”

At 11:57 p.m., the St. Francis collapsed, the left side giving way first, unable to support the weight of 13 billion gallons of water pushing against it. The route of destruction would be 54 miles long. The initial wall of water was 200 feet high and instantly killed 67 of the 70 people who lived just below the dam. By the time the water hit Castaic Junction, near present-day Magic Mountain, the water was 75 feet high. Santa Paula faced a torrent 25 feet high, with trees and broken houses acting like battering rams to obliterating everything in its path. Five and a half hours after the dam collapsed the muddy water lapped the Pacific Ocean near Ventura Harbor. If you drive Highway 126 today, you retrace nearly the exact route the water took.

Colorized image of the remaining portion of the dam — colorized by
Pony Horton of Tehachapi

The numbers were, and still 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 damaged. Three thousand volunteers searched for bodies. The reality is that the St. Francis Dam should never have been built where it was. Ninety years later there are barely any signs left of the once mighty St. Francis.

“Most people grow up experiencing history vicariously through a book or movie,” said local historian and dam expert Frank Rock, who leads tours of the dam site. “Being able to walk through the ruins of the St. Francis and experience tangible history of what is left of the dam, you experience a true sense of history, an understanding that this disaster happened on a day much like today and affected people very much like us.”

I sat down with Catherine Mulholland, granddaughter of William Mulholland, a few years before she passed away at her Chatsworth home. She was taken to the dam the day after it failed. “It’s one of my first childhood memories,” she said. “By now we know that homo sapiens have plundered the earth. We’ve dislodged, displaced and removed forests and oceans. We’ve flourished and we’ve also suffered. When you move water, things get destroyed in the process.”

Montecito Mud

It was water that destroyed parts of Montecito: water, mud, rocks, splintered houses, broken trees and mangled cars, to be precise. On Monday, Jan. 8, at 3:30 a.m. a torrential downpour destabilized the charred hills above Montecito after the Thomas Fire.

Mud and even boulders swept through Montecito during a rain storm a month after the Thomas Fire.
Photo Mike Eiason

“The sky was alight, you could hear this pulsating sound, flames shooting up 500 feet in the air, bright as day and it was raining — it looked apocalyptic,” said Montecito resident Lisa Cullen, owner of Montecito Landscape.

“We call it debris flow,” said Francis Rengers, a geologist at the U.S. Geological Survey. “What happened was a debris flow that moved like a wall and ended up being very destructive.” As the water moved downhill it flowed into streams and rivers, down streets, whatever the lowest and most pragmatic path was.

“Mud came in an instant, like a dam breaking,” said resident Ben Hyatt.

“A debris flow is a mud flow on steroids,” said Jon Frye, engineering manager for Santa Barbara County Flood Control District. He says that gravity pulls the mud down from the hillside to the lower levels, accelerating and accumulating anything in its path, eventually running into man-made structures; and it either has enough force to plow through them – taking that debris with it — or be diverted elsewhere, like onto streets, which is what happened on Olive Mill and Hot Springs roads, causing such devastation. “The area will be at risk for another three to five years,” he said.

When it was over, 21 were dead, two people still missing, and 127 homes were destroyed. The Army Corps of Engineers removed more than 450,000 cubic yards of debris. A boil-water alert lasted a month. This is reminiscent of the 2005 rains that precipitated the La Conchita landslide, which killed 10 people and buried a dozen homes.

What, if anything, can be done to mitigate the effects of rains like these? I visited Cullen, who along with her husband Chris, is a landscape design/build contractor. Though they experienced the entire drama of being evacuated from the Thomas Fire, and then the mudslides, their home was physically unscathed. Being in the landscape business they understood the topography of their property and knew that heavy rains filled part of their lot with several feet of water.

“We constructed a culvert, an informal seasonal creek that outlets large amounts of water,” she said. “Ideally what you want to do with water is slow it down. It’s always going to take the path of least resistance, so observe your property. You can control it with V-ditches, berms and swales,” she advised. Also, often existing large boulders and mature trees on a property can often help to determine a natural conduit. Granted, the Montecito debris flow was a freak occurrence, but it nonetheless should serve as a graphic reminder that water has a will of its own.

Matilija Removal

In the St. Francis and Montecito scenarios, water went where it wanted. With Ojai’s Matijila Dam, water is kept in place. In 1947 when Matilija Dam was constructed it could only hold 7,000 acre-feet of water. By contrast Lake Casitas brims with 254,000 acre-feet. (An acre foot is the equivalent of an acre of land holding 1 foot of water.) So why was Matilija ever constructed?

The effects of alkali-silica reaction are seen on the face of Matilija dam, breaking a buckled look. Photo Michael Cervin

“When the dam was installed it was a different era,” says Peter Sheydayi, deputy director of the Design and Construction Division of the Ventura County Watershed Protection District. “It was built for both water supply and flood control but it never had the capacity to weather drought like we’re in now. It has no benefit currently,” Sheydayi said, which is why plans for physically removing the dam have been ongoing for years. Well, that and the fact that the concrete monolith is becoming unstable. “The dam is in a state of alkali-silica reaction whereby the concrete weakens over time,” Sheydayi said. “The dam is safe currently, but we continually monitor it and take appropriate action to keep it safe.”

The simple view would be to remove it, restore the creek, allowing fish to once again move freely, and let everything return to a state of pristine beauty. It doesn’t work, however, as simply as that. For starters, the dam is filled with sediment that if released en masse, along with the water, would literally cover Matilija creek with dirt and debris, suffocating plants and stream life and physically altering the landscape.

“Work downstream has to be completed prior to physical removal, to protect infrastructure and property owners,” Sheydayi said, which accounts for two-thirds of the entire project.

In early February of this year the County Board of Supervisors approved a contract for technical studies on Matilija Dam removal. This is the first phase of the work, funded through a $3.3 million California Department of Fish and Wildlife grant, meaning that no local tax dollars are associated with this. The work is scheduled to begin in early July. But as fast as water pours forth from a dam, removal is the exact opposite — glacial.

And then there is the issue of what to do with 60,000 cubic yards of old cement. “It will be sent to a recycler,” Sheydayi said.

The projected cost? Somewhere between $111 million and 148 million.

“I think everyone is excited to not only remove the dam, which we know is weakening, but also to provide access for steelhead to gain entry to their ancestral headwaters, which they really need so they can eventually head back to the ocean,” Sheydayi said. That means a better ecosystem downstream, better balance of the Ventura coast, and more fish on our plates, eventually restoring what nature originally intended.