From the day the St. Francis Dam opened in 1926, it leaked. The folks in the farm towns downstream used to joke that they'd see you later "if the dam don't break."

Built by William Mulholland, known as the father of Los Angeles' municipal water system, the 1,300-foot span of concrete in San Francisquito Canyon held more than 12 billion gallons — a year's supply for the entire city about 50 miles to the south.

Mulholland had built his 19th and final dam because he wanted a little insurance for the booming metropolis. Southern California rainfall was, as always, capricious. His California Aqueduct had been built over a rift zone of the San Andreas fault, and he knew it was vulnerable. To make matters worse, Owens Valley farmers kept vandalizing the aqueduct.

The dam wasn't even 2 years old when it sprang new, muddy leaks on the morning of March 12, 1928. The dam keeper, Tony Harnischfeger, summoned Mulholland and Mulholland's chief assistant, Harvey Van Norman, who inspected the dam and vouched for its safety.

Twelve hours later, Harnischfeger and his 6-year-old son, Coder, were among the first to die — followed by more than 450 others.

A new documentary by Los Angeles historians and filmmakers Jon and Nancy Wilkman tells the tale of the dam and many of its forgotten victims. The Wilkmans use photo-realistic computer graphics and 3-D animation to re-create the structure and its collapse, showing how water saturated abutments and how an enormous landslide contributed to the tragedy.

Their technological detective work also tells the stories of many survivors, including the poor and powerless Mexican workers who were hit the hardest and yet often ignored by journalists and historians.

It was three minutes before midnight when the dam broke, freeing a 10-story-high avalanche of water to sweep 54 miles west to the ocean. It would take 5 1/2 hours to get there, but no official warning would be sounded for considerably more than an hour after the rupture.

Water engulfed whole towns, dozens of ranches, an Edison construction camp, the Harry Carey Indian reservation and trading post, and DWP Powerhouse No. 2. It swept into Castaic Junction and along the Santa Clara River bed to Piru, Fillmore, Santa Paula, Saticoy and, finally, the sea.

It demolished 1,200 houses, washed out 10 bridges and knocked out power lines. Bodies would wash ashore as far south as San Diego.

At midnight Lillian Curtis Eilers sat up in her bed at Powerhouse No. 2, just below the dam. She told the filmmakers that she saw "a haze over everything." Instantly she knew the dam had broken. Her husband lifted her and their 3-year-old son through a window and told her to run while he got their two girls. She and the boy survived; her husband and daughters did not.

Eilers heard someone calling. It was Ray Rising, a Department of Water and Power employee who had lost his entire family and owed his life to a floating rooftop. Together, she, her son and Rising — sole survivors in the community of 70 — waited until dawn for rescue, crying on a hilltop. Downstream, word spread of the flood. Neighbors knocked on doors, warning friends to get to higher ground. Some didn't budge because there had been no hard rains. But when little Thelma McCrawley Shaw's house started moving, she told the filmmakers, she knew it was time to get out. " 'Oh, you foolish child, you can't,' my mother told me," but out she went. She was found nine miles downriver, perched on a pile of debris.

Records indicate that the first official warning was issued at 1:20 a.m. By then, the water had traveled almost 18 miles and crested more than 40 feet, pouring over tents of 150 men at the Edison camp and killing 84.

Courageous telephone operators, including Santa Paula's night operator, Louise Gipe, stayed at their perilous posts, calling frantically ahead, trying to outrace the flood by telephone. They became known as the "Hello Girls."

Cliff Corwin of Fillmore was trying to flee in his car along Chambersberg Road when the water engulfed his Chrysler. "As I was making the turn onto the highway, crash goes the house, the barn and the windmill and — bing! — we were in it," he recalled in a 1978 Times interview.

Corwin survived, but his passenger, George Basolo, got out of the car and was hit by debris, dying instantly. "Georgie yelled to me, 'I won't be caught like a rat in a trap! I'm going out!' That was the last I saw of him."

As Corwin's car filled with water, he struggled out and hung onto the hood as the water pushed him along like a wave carrying a surfer. He said he could hear the crest of the water above him but was unable to see anything. "There was a high fog, no stars, no moon, and all the lights were out in the valley. It was as dark as a closet," he said.

When the wall of water slammed into Fillmore, a California Highway Patrol motorcycle officer, Thorton Edwards, raced ahead, siren wailing, through the streets of Santa Paula, 42 miles from the dam, to warn residents.

His action is said to have saved hundreds of lives, and the state awarded him a gold medal for bravery. Dubbed the "Paul Revere of Santa Paula," he was hired the next year as the town's police chief.

The acclaim also won him a bit part in "The Grapes of Wrath," playing a motorcycle cop who stopped the Joad family at the California border.

As the 75th anniversary of the disaster approached, and Santa Paula decided to pay tribute to the victims and the heroes, an unsavory part of Edwards' background came to light.

A Santa Paula cobbler, Jess Victoria, 84, who survived the disaster, remembers growing up in the town when Edwards was chief.

"He was an arrogant man who abused his power," Victoria said in a recent interview. "He walked into stores, grabbed a tie, a ham off the Hormel truck or whatever he wanted and walked away without paying for anything. Whenever he walked down the sidewalk, we had to get out of his way or he'd push us," .

Recalled Bob Procter, 81, who is on the board of directors of several local water companies: "He caused a lot of trouble. My uncle, former Mayor Guy L. Hardison, ran him out of town. When one of my uncle's Mexican farm workers showed up for work with his face all beat up by Edwards, Uncle Guy swore" he was going to fire Edwards. "With the full support of the City Council, he did just that."

As a result, the sculpture that had been intended to pay tribute to Edwards and another officer was called simply "The Warning," said Mary Alice Henderson, the president of the Santa Paula Historical Society. When the 3-ton bronze by Santa Paula artist Eric Richards is dedicated March 16, it will depict two generic officers — not Edwards.

Mulholland's legacy was also tarnished. An investigative panel reported its findings just 12 days after the collapse. It blamed Mulholland's design and said the construction of a great dam "should never be left to the sole judgment of one man, no matter how eminent ... for no one is free from error."

In 1995, a new book changed perceptions. It was based on a 1963 book called "Man-Made Disaster," by a Santa Paula journalist, Charles Outland, and on a research paper by a retired Stanford University professor named Bailey Willis.

In the new work, "The St. Francis Dam Revisited," geological engineer J. David Rogers concluded that there had been many problems with the design and placement of the dam that contributed to its failure. But the disaster's primary cause, he said, was unstable geology: The dam's eastern edge sat on an ancient landslide that shifted and plowed into the structure "like a bulldozer blade."

"Mulholland prided himself on getting the job done with a single-minded efficiency and at or below budget," Jon Wilkman said. "These same characteristics made him a hero to many in the construction of the aqueduct, yet they also ultimately led to the failure of the St. Francis Dam."

Today, the dam site is a stark, lonely hollow where a few chunks of the base lie scattered like headstones in a giant graveyard.

An excerpt from the documentary "The St. Francis Dam Disaster" will be shown at the Taper Auditorium in Los Angeles' Central Library on March 10, the Ventura County Museum of History and Art on March 12, and the Santa Paula Union Oil Museum on March 16.