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Fatal failures on America’s rivers

Thousands of dams are thought to be at risk of bursting in the United States – threatening to add to the country’s long list of tragic collapses. Joan Bien looks back 80 years to one of the worst.

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The 56-metre concrete gravity arch structure called St Francis Dam, located 70 kilometres north of Los Angeles, catastrophically failed at three minutes to midnight on March 12, 1928. The dam collapse unleashed a wall of water 38 metres high which bore down on the San Francisquito Valley. When it arrived at the ocean some 87 kilometres away, the dam break wave was still six metres tall.

As the flood rampaged through the canyons and down the Santa Clara River bed, everything in its path was obliterated. The exact number of casualties will never be known, but today’s assessment places the body count at more than 600. Bodies deposited in the sea continued to wash ashore for 30 years. The towns of Castaic, Fillmore, Bardsdale and Santa Paula were destroyed. Tens of thousands of acres of farmland in neighboring Ventura County were rendered unusable.

In 1928, dam failures and floods were nothing new in the United States. However, it was this catastrophe in southern California, and the enormous toll it took in human lives and property damage, that first grabbed the attention of government officials. 

The primary cause of the disaster was human error: mistakes were made in design and construction, which was overseen by one man – William Mulholland, head of Los Angeles Department of Water and Power (DWP). Just hours before the collapse and flood, Mulholland, had been told about a small leak and personally inspected the structure. He declared it to be safe. Mulholland was not only in charge of construction, but he was also the main engineer for the project. St Francis was his twentieth dam.

This disaster – in terms of lives lost, the second worst tragedy in California’s history after the 1906 San Francisco earthquake – was one of the worst US dam collapses, but it was by no means the last of them. A long trail of preventable catastrophic dam failures threads its way through modern American history. As recently as 2006, seven people were killed in a Hawaii dam burst.

In February this year, the Association of State Dam Safety Officials (a national organisation created in 1984 in a bid to reconcile the fragmented dam policies of different states) declared that 4,400 of the country’s dams were susceptible to failure – around 5% of the nation’s total. St Francis may have happened 80 years ago, but its relevance is still strong.

Mulholland, one of the most prominent and influential figures at the time, was financially and emotionally ruined by the dam’s collapse. At the coroner’s inquest immediately following the disaster, he did not try to place responsibility elsewhere. The San Jose News reported on March 22, 1928, “In his face and figure was reflected the great tragedy of the little valley. ‘I envy only those who are dead,’ he said. ‘We must have overlooked something.’” An important geological fact was uncovered more than 60 years later, San Francisquito Canyon had been the site of ancient landslides and the foundation was porous and unstable. Geologists now say there was no way for Mulholland to have known about those ancient slides back when the dam was being built.

Mulholland, an eighth grade drop-out and self-taught engineer, was propelled to fame after designing and building the 233-mile aqueduct that brought municipal water to Los Angeles in 1913, a project that initiated a struggle over water rights known as California’s “Water Wars”. Los Angeles is a semi-arid desert and its growth was limited by a lack of water. But some 200 miles north in the Owens Valley was a source – Owens Lake. After the aqueduct was completed in 1913, so much water was demanded by Los Angeles that the entire Owens Lake dried up. In 1924, a group of farmers and ranchers rebelled and blew up parts of the aqueduct, but the sabotage did not stop the flow of water south to Los Angeles.

When it came to decisions about water in the city, no one had authority over Mulholland. The St Francis Dam was intended to hold a year's supply of water for Los Angeles, and construction commenced quietly in a bid to avoid the wrath of local farmers who depended on the water being diverted for the reservoir.

During the construction phase, Mulholland unilaterally decided to raise the height of the dam by three metres on two different occasions. His unconventional building methods went unquestioned. However, his failure to widen the base after extending the height of the concrete dam another six metres may have contributed significantly to its catastrophic failure.

Some lessons were learned from the disaster. For the first time, dam-safety laws were passed in California and some of the surrounding states. And never again would only one person be allowed to make all of the decisions on engineering and safety, construction and maintenance.

However, most of the dams in the United States remained completely unregulated. And the disasters continued. In December 1963, five were killed in the collapse of the Baldwin Hills Dam in Los Angeles, which had knowingly been built on a major fault line. The cause of the collapse was believed to be foundation subsidence due to nearby oil-drilling. In 1972, a dam failure at Buffalo Creek, West Virginia, caused 500,000 cubic metres of black waste-water to pour into a populated area, killing 125. The dam had been built in 1968 on top of coal slurry sediment instead of bedrock, and the coal company was convicted of murder. The same year, more than 238 people died in the Black Hills Flood in South Dakota after heavy rainfall caused a dam to fail because the outlets had not been cleared of leaves. There are many other examples.

The flurry of fatal dam failures around the country in the 1970s finally prompted the federal government to issue voluntary safety guidelines. The federal government owns or regulates only 14% of the country’s dams, while the remainder is regulated by individual states. Even at federal level, oversight is hugely fragmented: responsibility is divided among 14 different agencies including the Army Corps of Engineers, the Department of Homeland Security, the Department of Defense and the Department of the Interior.

But these guidelines have not extinguished the problem – if the Association of State Dam Safety Officials’ figures on vulnerable dams are correct, the risks are still there. And the consequences can be still be severe: seven people were killed on the Hawaiian island of Kaui in March 2006, when the Ka Loko Reservoir failed after its private owner performed illegal grading operations on land near the dam. The state of Hawaii had failed to inspect the site. Seven people were killed in the flood and many more homes and farms were destroyed. The owner agreed to a US$25 million (162 million yuan) settlement to be shared among the victims. More than five years later, he is still awaiting trial for manslaughter.

Human error has been identified as the cause of a long list of catastrophic dam failures in the United States. Shoddy construction, greed, negligence and failure of government agencies to adequately oversee safety issues have all been preventable causes of such catastrophes. The Aspen Institute, an environmental think-tank that has studied the problem of ageing and decaying dams across the United States, has recommended that some existing structures be dismantled – with community input, recognition of the rights of private dam-owners and timely inspections of structures – before problems can turn into disasters.


Joan Bien is a freelance journalist based in California.

Homepage image from US Geological Survey Photographic Library shows the remains of the collapsed St Francis dam. 

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