Nathan Masters: A few minutes before midnight on March 12, 1928, the lights in Los Angeles flickered, a moment of unease that quickly passed, but 50 miles north, life was about to change forever.

When the St. Francis Dam collapsed that night, it unleashed a deadly torrent, carving a path of destruction all the way to the Pacific Ocean, claiming more than 400 lives.

Today the tragedy has largely faded from memory, but its scars remain etched into the landscape, waiting to be uncovered by those who know where to look.

♪ This program was made possible in part by a grant from Anne Ray Foundation, a Margaret A. Cargill philanthropy.

The irony is cruel.

One of California's worst disasters came from an effort to fortify against disaster.

In August 1924, construction began on the St. Francis Dam.

Los Angeles was booming, and William Mulholland, the city's water chief, had a big concern.

The city's water supply depended on the 233-mile Owens Valley Aqueduct.

This lifeline crossed the San Andreas Fault, and Mulholland knew that a single rupture could leave L.A. high and dry.

To make the system more resilient, Mulholland built the St. Francis Dam just north of the city on the safer side of the fault.

Its reservoir was designed to hold enough water to supply L.A. for two years in case disaster struck.

It was a bold plan to secure L.A.'s future, but in a tragic twist, the dam meant to protect the city instead unleashed a catastrophe no one saw coming.

♪ Nearly a century later, its structural twin still stands right in the heart of Los Angeles.

Like the St. Francis, the Hollywood Reservoir Dam is a concrete gravity-arch structure designed by Mulholland himself.

I met up at the dam with friend and architecture writer Geoff Manaugh to explore its ties to the St. Francis disaster.

This was supposed to be a civic monument, right, a civic monument to L.A.'s water infrastructure.

Manaugh: Yeah and important not just culturally, but, you know, for millions of people moving here over the years, you know, all have an immense need for new sources of water and electricity and all of the things that we take for granted, and it was people like William Mulholland operating in the background who actually really had the real power in the city, you know, were able to reform the landscape itself.

Masters: And Mulholland really took that responsibility personally.

He agonized over whether L.A. could meet the water needs of its citizens, and, I mean, that's one of the reasons why this place was built.

Manaugh: It's amazing, actually, if you look out over and you look at some of these distant neighborhoods, and you can imagine just how much of a feature this dam would have been for the city.

Masters: Right.

It's also interesting to think that literally overnight, a dam like this went from being something to celebrate to something you hide.

After the St. Francis Dam collapsed, panic rippled through the communities below the Hollywood Reservoir.

Could the Mulholland Dam be next?

In response, the city quite literally covered up the problem, lowering the reservoir by 31 feet to reduce pressure and blanketing the dam with tons of earth and landscaping.

Trees took root, and the Mulholland Dam quietly disappeared into the Hollywood Hills.

♪ Manaugh: All right, so we're getting on the freeway here, starting off our road trip.

Masters: Cheers.

Manaugh: Cheers, so we're heading up to the Cascades, where the water comes into Los Angeles from the aqueduct... Masters: Since 1913.

Manaugh: where William Mulholland famously said, "There it is.

Take it," referring to all the water that had been stolen from the Sierra Nevada.

Masters: Just a magical line, right?

Manaugh: Yeah, so you can see it from the freeway.

I think most people who drive on the 5 heading up to San Francisco, for example, won't know what it is that they're looking at, but that is actually part of the water supply for the city.

Masters: It's something like half of the water supply for the City of L.A. Manaugh: Yeah.

It's quite a lot... Masters: Yeah.

Manaugh: and it's a historic landmark.

Oh, there it is.

Yeah.

You can see the water.

Oh, yeah.

Look at that.

Masters: Yeah.

♪ After snapping a few photos at the Sylmar Cascades... Manaugh: It wouldn't be a road trip if we weren't covered in documentation.

Masters: we wound our way up San Francisquito Canyon to the enormous penstocks that feed Powerhouse No.

2.

Wow, so this is L.A.'s water supply... Manaugh: Yeah.

Masters: and there are 3 of these things, too.

Manaugh: Yeah.

Masters: You can see those are giant pipes.

Manaugh: Yeah, coming out of the mountain, obviously blasted tunnels all the way through, reinforced with concrete, and then they plunge down over the edge here down to Power Station 2.

♪ Masters: So these maps are from right around the time of the disaster, roughly 1928.

We started here, Lake Hollywood, and we drove.

Actually, when you look at this map, of course, what's missing here?

Freeways.

There are no freeways.

This is the prefreeway map.

It's not marked here, but the Sylmar Cascades are right around here... Manaugh: Mm-hmm.

Masters: and then we drove up San Francisquito Canyon.

Manaugh: Yep.

Masters: I see St. Francis Dam is on here.

Manaugh: Yeah.

It's amazing.

Masters: Yeah, and actually, the aqueduct is on here, too.

Manaugh: Oh, yeah.

You can see it.

Masters: Wow.

Manaugh: Wow.

Masters: It's not every day you stand atop the city's water supply.

Manaugh: No, not at all, yeah, but it's incredible to see these things coming out of the mountain.

Masters: So we're here atop Powerhouse No.

2.

Dam site's a mile and a half up canyon that way, so let's go check it out.

Manaugh: Yeah.

Let's go up and see it.

Masters: Let's take a look.

Manaugh: So how many road trips have you taken visiting sites of infrastructure around L.A.?

Masters: Ha ha ha!

I mean, I've taken quite a few, actually.

Manaugh: In terms of Mulholland himself, you know, some people think he's a hero.

Some people think he's a villain.

Masters: I mean, he's a complicated guy... Manaugh: Yeah.

Masters: but I think he gets a bad rap overall, largely because of "Chinatown," right, the film that shapes everybody's thinking about L.A.'s water wars... Noah: It's all taken care of.

See, Mr. Gittes, either you bring the water to L.A. or you bring L.A. to the water.

Masters: but in terms of his personal character, there's really nothing evil about William Mulholland.

In terms of the effects that he had on the ecosystem, on the Owens Valley, and then, of course, his role in the St. Francis Dam collapse, sure, you can knock him for those things, but he's the man who made the modern metropolis of L.A. possible.

To me, it seems like L.A. is often singled out for opprobrium.

Manaugh: Well, people love hating Los Angeles.

Masters: Yeah.

Yeah.

Though a coroner's inquest cleared Mulholland of criminal liability, the collapse destroyed him both professionally and personally.

"On occasions like this," he told the inquest, "I envy the dead."

As Geoff and I continued our journey, we met with archeologist Ann Stansell and seismologist Lucy Jones at the dam site to uncover what really happened that fateful night in 1928.

There really are very little visual hints that this is the site of one of the greatest civil engineering disasters in American history.

I mean, there are no road markers.

There's no signs.

Stansell: No.

It's very much on a bypassed road.

Most people aren't able to find their way here, and when they get here, sometimes they don't even know what they're looking for.

It's only more recently that they're actually teaching it in the local elementary schools.

The tombstone stood for a year and was dynamited in the summer of 1929.

That was a visual reminder of the disaster but also a huge source of vulnerability and not a good look for the city or the water department.

Masters: Now, when we're talking about this dam collapse, I hear there are a lot of different explanations for what might have happened.

Stansell: I think if you asked a handful of different engineers, they might all have different theories as to why it failed.

The most recent explanation that's been well studied is by J. David Rogers, a forensic engineer out of the University of Missouri at Rolla, and he believes that there was an ancient landslide that reactivated on the roadway just behind the dam shortly before it failed.

He also has found that some of those include raising the height twice during the construction without increasing the width, and it leads to excess hydrostatic pressure of pushing the dam forward.

Other folks, especially at the coroner's inquest, they looked at this material and thought that it was not good-quality concrete, and, in fact, at the inquest, they put a piece of the concrete in a glass of water while the folks were testifying and saw that it did start to break apart quite easily... Masters: Oh, wow.

Stansell: and break down.

However, J. David Rogers didn't feel that it was the concrete individually that caused the issue.

Jones: There's a quite beautiful-looking exposure of a fault down here.

Now when you build a dam or explore a site, you check out preexisting landslides because we know that the excess water pressure that is created by just the weight of the water in the reservoir seeps down and will tend to activate.

If you have an existing slide surface, you can activate it just because of the weight of the water.

Masters: There is a cruel irony, though, that Mulholland built this as preparedness, disaster preparedness in the event of an earthquake, and yet it was a disaster in its own right.

Jones: Well, and I think that fundamental thing that natural disasters aren't natural, right?

We have natural hazards, but the disasters are how humans get ready for it, and you've got to think ahead.

You know, it's that multiple cascading idea again.

You got to consider a lot of different things to cover it.

Masters: So we're talking about this dam collapse and the ensuing flood as being a disaster, but a lot of environmentalists consider dams themselves to be disasters, right?

Jones: Protecting people from floods was considered a really high calling.

Engineers were proud of the work they did because we had numerous floods that were killing lots of Southern Californians, and we built our flood-control system.

It's very interesting to talk about naturalization with the flood-control people.

Masters: Mm.

Jones: A lot of them are really opposed to naturalizing these things because we'll go back to a time of increased risk, so we got to figure out what the balance is.

[Camera shutter clicks] Masters: Just down the canyon is the site of dam keeper Tony Harnischfeger's house, now shaded by a majestic live oak.

On the day of the disaster, he noticed muddy water seeping from the dam's west abutment and raised the alarm.

Mulholland personally inspected the dam and declared it safe.

Hours later, the dam gave way, sending a 10-story wall of water surging down the canyon.

Harnischfeger was its first victim.

His body was never recovered.

So I think this is what's called the Pyramid, and, of course, from the highway, it looks just like a rock, right... Manaugh: Yeah.

Masters: but it is actually a massive piece of the face of the dam that was carried by the floodwaters about a quarter-mile up there quarter-mile down here.

Manaugh: Yeah.

Masters: Just--concrete doesn't float, right?

Manaugh: No.

Yeah.

It's unimaginable, the force and the power of the water that would have dragged this thing all the way down here.

Masters: Up close, you can see that it really is concrete.

It has... Manaugh: Yeah.

Masters: these little, smaller stones embedded in it, and actually, there's--there's rebar sticking up out of it... Manaugh: Oh, yeah.

That's interesting.

Masters: right here.

Manaugh: Yeah.

You can even see some of the facets of the old steps.

Masters: This was the face of the dam... Manaugh: Yeah.

It's incredible.

Masters: from all the way over there.

Manaugh: Yeah.

Masters: Wow.

Wow.

Seeing these traces of history still hiding in plain sight was both sobering and fascinating.

Geoff and I jumped back in the Jeep and continued west, following the flood's path through the Santa Clara River Valley toward the ocean.

♪ Here we are, Fillmore, 19 miles, so this highway takes 45 miles to get to Ventura.

That's the flood.

Manaugh: Yeah.

Masters: It went another 44 miles, lost some steam, but still packed a wallop all the way to the coast.

Manaugh: Yeah.

Masters: Wow.

Manaugh: Yeah.

That's so much water.

♪ Yeah.

For the people who aren't in the car with us, it's a really beautiful landscape.

The hills are just these beautiful, rolling hills covered in vegetation.

You know, one of the tragic aspects of what happened is that the people most affected were people who didn't benefit from the thing that collapsed.

Masters: Oh, right.

Manaugh: You know, like, the dam and the water that it held back didn't necessarily benefit people in this community.

Masters: In that way, it's analogous to the Owens Valley, right, although... Manaugh: Yeah.

Masters: we're talking about a sudden disaster here.

There, you have a slow, incremental disaster.

About 40 minutes later, we rolled into Fillmore.

♪ Manaugh: Here we are, looking at a lovely downtown Fillmore.

Masters: Yeah, but a lot bigger than it used to be.

All these homes are definitely in the flood path.

♪ The Fillmore Historical Museum keeps the memory of the flood alive, preserving the story of how it forever changed this town.

We sat down with Martha Gentry, a third-generation Fillmore resident and the museum's executive director.

Where does the St. Francis Dam disaster fit into the history of Fillmore to a local?

Gentry: Uh, well, to the current locals, it's very important.

I did not know anything about the St. Francis Dam till long after I was out of high school and gone from Fillmore and then came back and we started studying it here, but it always amazed me that none of my family who were here during the event ever said anything about it.

Masters: You'd think it would be part of the family lore.

Gentry: You would think it was, and my mother's very best friend when the water hit, her name was Thelma McCauley Shaw in her married life, and her family woke up in the middle of the night, and they were standing there.

The house is moving, and what do you do?

Well, she survived.

Her family did not.

Masters: Oh, wow.

Manaugh: Wow.

Gentry: It was very much happenstance.

McCauley Shaw: Mother woke me up.

I was home with the measles at the time from school, and she woke me up and put a coat on me, and she thought that it was raining hard because it was making a noise in the trees, and she dressed me, and I said, "I'm going to get out," and she said, "Oh, you foolish child, you can't," and I emphatically said, "I am going to get out," and I went out the back door of the house and went right where the flow of the water over to the main channel--we were across the river--and went right into the main channel, and my family--which consisted of my father and brother, 17, and my dad--they went out the other door right into the flow of the water that pushed them, I'm sure, right into the tumbling house, and that's what happened with them.

Gentry: Those were items that were sold by photographers after the fact.

Masters: For 35 cents, I see.

Gentry: 35 cents.

Masters: Wow, so people-- Gentry: People did want to keep some memories of it, so they did that.

Manaugh: Yeah.

You can see the-- Masters: The tombstone, yeah.

Manaugh: the tombstone, yeah, where we were standing earlier today.

Masters: That's right.

We were standing right on top of that.

Wow.

Gentry: They took photos after the fact, acts of heroism, the people walking down the river trying to find the deceased, find the survivors, like Thelma.

Manaugh: And what was done with most of the debris?

You know, you don't have a lot of artifacts from the flood.

Gentry: It was burned.

There are a lot of videos of the gathering of the debris, whether it was wood debris or whatever, but they had to make sure that they had found everybody, and they did not want to necessarily burn animals, either.

♪ Masters: So I heard that some people after the flood relocated their houses.

Gentry: There were a lot of houses that were damaged because the water went really to the south.

Once it left, basically, the Fillmore city limits, it went south into Bardsdale, and several of those houses were floated off of their foundations.

One of these houses belonged to the Gage family, and they were trapped in the house and couldn't get out, so Mr. Gage got his shotgun out, and he shot a hole in the ceiling and then shot a hole in the roof so he could get the family into the attic and then onto the roof of the house.

Masters: Oh, wow.

I've noticed when you're referring to the victims and the survivors, for that matter, you're referring to them by name.

I feel like you've grown to know these people.

Gentry: Some of these people-- Well, I knew the Gage family, the family that's closer to my age, so yes, and we've done enough of these stories to become quite familiar with some of these families.

Margaret Rudkin, her story was that they couldn't get out, and her mom got them all dressed in their Sunday best, and they stood on a bed and waited for it to pass or waited to die, and they all survived, of course.

♪ Masters: This is a truly large folder.

Here we are.

Gentry: Yes.

It is.

Manaugh: These are amazing.

Gentry: They are amazing.

Masters: You can see how these hillsides have been scoured of any soil or vegetation.

That's just down to the bedrock there.

Gentry: Yeah, and in several places along the river, it went clear to the clay layers below, which is one of the reasons the early agriculturalists didn't think anything would ever come.

Masters: Oh, this is the actual dam and reservoir.

Manaugh: Yeah.

It's the water.

Gentry: Yeah, before it collapsed.

My property would have been right about in there.

That's where my family was.

Manaugh: I can't believe that the water was still 40 feet high when it got here.

Gentry: Once it left Fillmore, it spread south, and by the time it got to Santa Paula, it was back in the channel, and then it spread north, so Santa Paula had more damage in town along Harvard Street than we had here.

You're never truly safe when it comes to water.

Masters: It's a little unnerving to hear that.

Manaugh: Sobering thought.

Gentry: If you have a major earthquake and it's one of the dams involved, head for the hills.

Manaugh: Yeah.

Gentry: Ha!

♪ Masters: Agriculture still defines the Santa Clara River Valley today, much as it did when the floodwaters tore through in 1928.

Francisco's Fruit Stand, which opened in 1983, specializes in local oranges, avocados, and other produce grown right here on the floodplain.

Before leaving Fillmore the next morning, we made sure to stock up on snacks for the road.

I mean, these pineapples look amazing, but these are not road-trip food.

Manaugh: That would be pretty hard to eat in the-- Masters: Yeah.

Mandarin.

We'll try that.

Yeah.

Manaugh: Sweet.

Masters: Good.

We have quite a haul here.

All right.

Thank you very much.

The flood path was home to many migrant workers, most of whom spoke Spanish.

That made it difficult when emergency calls spread across the valley warning of the disaster.

Professor Jose Alamillo, whose family worked in the lemon industry, has been collecting and preserving the stories of the Mexican American families who survived the flood.

So this building has been here for a long time.

Alamillo: Oh, yeah.

Masters: More than 100 years.

Alamillo: Definitely over 100 years.

Manaugh: Mm.

Alamillo: Yeah.

It's the original location of the newspaper right here.

Manaugh: Oh, wow.

Alamillo: So this is the newspaper "La Voz de la Colonia," a Spanish-language newspaper published from 1923 to about 1932.

Masters: What does that mean, "The Voice of the--" Alamillo: "The Voice of the Colony," the voice of the people, and this was published by Manuel Reyes, the editor, in this building here that we're in.

This is where they had the printing press.

The night of the disaster, Manuel Reyes hears sirens outside, and he goes to find out that there's a flood coming down towards Santa Paula.

He hitches a ride to rescue his family, who's located in the south side where his house is.

Masters: In the flood path.

Alamillo: In the flood path, yeah, so he rescues his family.

He comes back to the printing press here... Masters: Right here.

Alamillo: and he starts working on the next issue of "La Voz de la Colonia."

Masters: Which is what we're looking at.

Alamillo: That's right.

Look at the headlines-- "Luto.

Desolacion.

Muerte, Heridos!"

"Mourning.

Desolation.

Death, Injured!"

Masters: Wow.

That's a screaming headline.

Alamillo: It's a screaming headline.

Masters: It's appropriate, given the circumstances.

Alamillo: Yeah.

It's like you cannot miss it.

Here, I want to show you this, too--"The Mexicans Who Did Their Duty," the Mexican heroic efforts of the residents themselves.

I mean, these are the stories that were never told in the writing of the St. Francis Dam disaster that we only know because of this newspaper that was found years later, several years ago, in fact.

This was in a basement of the E.P.

Foster Library in Downtown Ventura.

We had no idea that newspaper existed.

Manaugh: And were there special editions that the newspaper put out in the days after and the weeks?

Alamillo: Yes, so if you continue on, we see that there are special editions like this one here.

Manaugh: Oh, wow.

Yeah.

Alamillo: It also talks about the role of the Mexican Blue Cross, right?

This was a charitable organization led by women across the United States.

You had Mexican charitable organizations, like, mutual-aid societies that would assist the afflicted, the poor, and the Mexican Blue Cross from L.A. came to Santa Paula to help and assist in the rescue effort, and the most important service they provided was the translation and interpretation for the American Red Cross officials, so if we flip over to the next few pages, here you have, "Aviso--register your claims, your injury claims, from the flood," and it talks about where to go, so it provided an important service.

Masters: It's critical information for the community.

Manaugh: And we've seen a lot of text.

I'm curious.

You seem to also have a lot of-- a really strong photo archive.

Alamillo: I do, and I want to show you some of those photos.

The "L.A. Times" photographer made their way out to Santa Paula the day after, and they took a lot of amazing photographs of the tent colony, which they called the relief tent colony, that was located on the east side of town.

It was a segregated part of the city, and here, their photo of the children is reprinted and published in newspapers, the "L.A. Times," but also in the Spanish-language press.

Here, I want to show you this one here particularly because it shows the relief camp, right, but look where it's located, next to the oil tanks... Masters: Yeah.

Wow.

Alamillo: because there was oil tanks.

I mean, this was an oil town, as well, right?

Masters: Sure, and I feel like the story of the relief effort often gets lost in the larger narrative.

I mean, we can focus, but this is the aftermath that people had to deal with for months and years, and actually some repercussions continue to this day.

Alamillo: Yeah.

Yeah.

I mean, you have families who still talk about it within their own family story, so this is Genevieve Luna.

She's 102 years old here.

I got a chance to interview her.

She tells about, you know, how she survived.

Her dad essentially got her and her siblings out quickly before the waters entered the home, and all she remembers is running fast up the hill, and then you have another family, the Irene Chavez Luna family, and so this story is interesting because her mom is one of the survivors.

Her mom was Soledad Luna.

She was 11 years old.

She was basically one of the survivors who floated down the mattress with her mom and her siblings... Masters: Oh, wow.

Alamillo: and she talks about how that traumatic episode haunted her for years.

Masters: Wow.

Alamillo: Yeah, so there was definitely intergenerational trauma, and it's hard to talk about, you know, and it's not easy to get them to open up about it, too, so it's taken me years to gain their trust.

Masters: It's easy to reduce this disaster to cold numbers-- 12.4 billion gallons of water, 1,200 homes destroyed, 431 lives lost--but--thanks to the work of people like Jose, Martha, and Ann--the human stories behind those statistics come to life.

Through their efforts, the pain and resilience of those who faced the floodwaters are remembered and preserved.

Manaugh: All right.

We're beachward.

Masters: Beachward.

Manaugh: Yeah.

I think it's incredible, though, you know, the things that we've learned and heard about, especially stories of survival, you know, how people got out of their houses, you know, all of the panicked ingenuity that comes with being trapped and realizing that you have to get your family out of a house that's drifting downriver.

Masters: Yeah.

Panicked ingenuity is a good way to put it.

Manaugh: Yeah.

Masters: So we've reached the end... Manaugh: Yeah.

Masters: the end of the road trip.

OK, so this is the one that we started with, right, because this shows the Hollywood Dam.

Manaugh: Yeah, so we started off here at the dam.

We got--not only got to see the ruins, but just realized just the unbelievable extent of all the water that was drained out of that reservoir, you know, 80 feet of water.

Masters: That's a lot of water.

Here's Santa Paula and then the last little bit of today down to here.

Manaugh: Well, why don't we see where the river hits the sea?

Masters: Yeah.

It's right over there.

♪ So it's easy to fall in the trap of saying that the disaster site is where the dam collapsed, but if you think about it, in actuality, this was one 54-mile-long disaster site that ends right here, and what's astounding about that is, of course, if you look around here, this landscape couldn't be any more different from San Francisquito Canyon... Manaugh: Mm, but I really like that way of thinking about it, that, you know, it's a 54-mile-long disaster site.

You know, it's something that begins in the mountains and forms this huge scar that comes all the way down, you know, goes through communities.

It goes through people's lives, and then it ends right here where we've driven.

Masters: And a scar, as we've learned, not just in physical terms, but also human terms.

Manaugh: Yeah, on people, their experience, on-- You know, it affected individual members of the families, all the loss and mourning that was a part of that, as well.

[Camera shutter clicking] ♪ Masters: This program was made possible in part by a grant from Anne Ray Foundation, a Margaret A. Cargill philanthropy.