Forgotten structures (pt. 1) — St. Francis Dam

‘St. Francis Dam under construction in 1925’ — L.M. Mystone

In this blog — titled ‘forgotten structures’ — abandoned developments of the 20th century, littered across the globe, are brought back to life. With the aid of photography collections and archival memoirs, we explore the legacy of intriguing structural ruins which time has slowly left behind. Each week, a new case is introduced and added to the list. Ultimately, the blog will construct a comprehensive collection of structural gems which deserve to be remembered. In doing so, we debate the general question of ‘what should be done with abandoned structures?’

Where there is ruin, there is hope for a treasure Rumi

This week, we explore the tragedy of the St. Francis Dam, CA. It’s never nice to start on a sad note, but, as the 90th anniversary of one of California’s most deadly disasters passes, it is important to pay homage to the incident and the remarkable structure it involved. Ultimately, on March 12th 1928, barely two-year’s after construction, the St. Francis Dam collapsed and slid into obscurity, taking over 400 lives with it.

The dam, a curved concrete wall in the middle of the San Francisquito Canyon, was built to create a large regulating and storage reservoir for the city of Los Angeles. The reservoir was an integral part of the city’s water supply infrastructure. Located about 40 miles northwest of downtown Los Angeles, the dam was designed and built between 1924 and 1926 by the Los Angeles Bureau of Water Works and Supply. The department was under the direction of its General Manager and Chief Engineer, William Mulholland.

Mulholland, a self-taught engineer, and his assistant inspected the dam in the morning of the 12th of March. The dam had already begun to show signs of stress, and there were a number of temperature and contraction cracks appearing, with a small amount of seeping occurring under the abutments. While he appeared concerned, Mulholland deemed the cracks to be of average depth for a dam of its size and took no further action. 12 hours later, he was proven horribly wrong.

Two minutes before midnight, on the very day that Mulholland decided it was safe, the St. Francis Dam collapsed. As transformers blew and 12.4 billion gallons of water barrelled down the canyon, no one between the eastern canyon’s drought-ridden hills and the Pacific Ocean had any idea that an inland tsunami was about to wash them away. Collapsing from the bottom, the enormous concrete walls crumbled and the intimidating structure disappeared within minutes.

The dam keeper’s cottage was first to go. Then the waters destroyed Powerhouse 2 and everyone inside. Emptying into the Santa Clara riverbed, the deadly wall of water headed for more populated ground, wiping out parts of modern-day Valencia and Newhall, crossing what is now Interstate 5 and completely washing away the town of Castaic Junction. The flood then laid devastation to three more communities: Fillmore, Santa Paula, and Bardsdale. Incredibly, the flood waters travelled over 57 miles in just 5 hours and 27 minutes. Unsurprisingly, the collapse of the dam remains one of the worst American civil engineering disasters. Worse still, it remains the second-greatest loss of life in Californian history, only eclipsed by the 1906 San Francisco earthquake and fire.

In response to the disaster, the California legislature created an updated dam safety program and eliminated the municipal exemption. Before this was added, a municipality having its own engineering department was completely exempt from regulation. On August 14, 1929, the Department of Public Works, under the administrative oversight of the State Engineer, was given authority to review all non-federal dams over 25 feet high or which would hold more than 50 acre-feet of water. Additionally, the state was given full authority to supervise the maintenance and operation of all non-federal dams.

Needless to say, Mulholland resigned, taking full responsibility, and the dam was never rebuilt. The concrete ruins which survived included the remains of the centre of the structure, which earned the title of the “Tombstone.” A few months after the catastrophe, due to increasing concerns regarding safety, the Tombstone was demolished. While further ruins survived, the only visible remains of the St. Francis Dam are weathered, broken chunks of grey concrete and the rusted remnants of the handrails that lined the top of the dike. The scar from the ancient landslide can still be seen from San Francisquito Canyon Road and, while not quite representing a tourist hotspot, passersby regularly trek through the desert to view the site.

The severity of the disaster, as well as Roman Polanksi’s neo-noir film ‘Chinatown’ — which delves into issues of municipal power and deceit, while appearing to be loosely based on the St. Francis incident — ensures the memory of the tragedy remains. As for the enormous concrete structure of the dam itself, only rubble serves as a memory of its existence. Perhaps, in respect of the disaster’s victims, this is the way it should remain.

Research assistant at Queen's University Belfast

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