"This is the driest dam I've ever seen." These words were said by William Mulholland in response to warnings that the Saint Francis Dam was leaking and may collapse. Twenty-four hours later, the reservoir was empty, the water was in the Pacific Ocean 54 miles away, large pieces of the dam lay scattered for over a half mile down river, perhaps six hundred people or more were dead, and over two thousand homes and other buildings were damaged or swept away. William Mulholland had been celebrated as instrumental in bringing water to the City of Los Angeles allowing it to grow into a major city. The Saint Francis Dam disaster signaled the end of his distinguished career.|
For thousands of years, water flowed harmlessly through San Francisquito Creek, when there was any water. Sometime in the past there had been a large landslide, but it was not detectable when William Mulholland, chief engineer and general manager of the Los Angeles Department of
Water and Power (then called the Bureau of Water Works and Supply) decided this was a good location for a reservoir. There had been attacks on the Los Angeles Aqueduct and this new reservoir would hold a year's supply of water. Between 1924 and 1926, under the supervision of
Mulholland, the Saint Francis Dam was constructed across San Francisquito Canyon.
Immediately after construction begun in 1924, Mulholland decided to raise the height of the dam by 10 feet to increase the capacity of the reservoir from 30,000 to 32,000 acre-feet of water. In July 1925, when the dam was about half-completed, he again added another 10 feet. This brought
the total height of the dam to 195 feet and the capacity to over 38,000 acre-feet. Because of the increased height, a "wing dike" had to be added along the top of a ridge near the western abutment to prevent water from spilling over the ridge. No major changes were made to the design of the dam to accommodate the additional load.
St. Francis Dam was formally dedication in May of 1926 and for almost two years, the dam did it's job slowly filling. During this time, several temperature and contraction cracks appeared in the dam and its abutments. Mulholland and his assistant Harvey Van Norman inspected the dam
several times and concluded that the cracks were normal for a concrete dam this size. As a side note, the Van Normal Dam in Granada Hills came close to suffering a collapse after the 1971 Sylmar Earthquake and was replaced.
The reservoir had reached full capacity by March 7, 1928 and filling ended. In the same week, cracks and sagging in the road along the east shore were reported. By the morning of March 12th, the roadbed had sagged almost 1 foot and dam keeper Tony Harnischfeger discovered a new leak
in the dam. Mulholland and Van Norman inspected the new leak and pronounced the dam safe.
That night, at three minutes before midnight on March 12, 1928, the dam catastrophically failed. A motorist had just pasted the dam and heard a rumble behind him. The break was relatively sudden and a 135 foot high wall of twelve billion gallons of water, the floodwave (also called
dam break wave), began surging down the quiet canyon at 18 miles per hour. The dam keeper's cottage (1/4 mile below) was the first to go followed quickly by a power plant. Large pieces of the dam were later found a half mile downstream.
The wave lost height and slowed as it went, but grew wider as it entered flatter ground. It serged through present-day Valencia and turned west toward Ventura County following the Santa Clara River bed. Past the future site of Magic Mountain and the site of the long abandoned Mission Estancia San Francisco Xavier through Castaic Junction. It continued flowing west, slowing to about 12 miles per hour as it went, dragging tons of mud, debris, houses, and people with it through Fillmore, Bardsdale, and Santa Paula. Downstream, everything possible was being done to alert people and
evacuate the areas around the river.
Finally about 5:30 a.m the flood reached the Pacific Ocean at Montalvo, 54 miles and five and a half hours from the dam site. By this time is was only traveling about 5 miles per hour, but in a flood almost two miles wide.
The true death toll is unknown. Bodies were swept out to sea to wash ashore as far south as Mexico. Bodies may yet be buried in debris and some were still being found in the 1950s. The official death toll in August 1928 was 385, the current death toll is estimated to be over 600, and
this doesn't include an unknown number of itinerant farm workers camped in San Francisquito Canyon. Ten bridges were washed out, 909 homes were totally destroyed and 1,200 were damaged, and power was out and communities disrupted over a wide area.
Following the disaster, an inquest was held. Mulholland was cleared of any charges since technology at the time could not have detected the instability of the rock from that ancient landslide on which the dam was built. Mulholland was quoted as saying he "envied those who were killed" and continued, "Don't blame anyone else, you just fasten it on me. If there was an error in human judgment, I was the human, and I won't try to fasten it on anyone else." Soon after, Mulholland retired and retreated into isolation. He died in 1935 at the age of 79, as broken
as his dam.
Informative video on the disaster.