Lives, Life Styles Lost to Floodwater --Until the Dam

The Sepulveda Dam was built to end or ameliorate the floods that periodically ravaged the San Fernando Valley. There were 17 serious floods between 1815 and 1938, according to Anthony F. Turhollow, historian for the Corps of Engineers Los Angeles District.

Because it is almost completely surrounded by mountains, “it is possible for the San Fernando Valley to become a lake,” Turhollow said. “In fact, in 1861 and 1862 it did become a lake, a real lake, roughly from where Ventura Boulevard is today to Northridge. There were only a few hundred people in the Valley then, a few ranchos, some cattle, and as long as the population was small there was no big problem.”

But as Los Angeles expanded, there was a big problem.

“There were very severe floods after the real estate boom of 1884,” Turhollow said. In that year, a flood washed away 50 homes in the Valley.

“Flood-control planning started in 1914, after a major flood that year in which there was tremendous damage and some loss of life,” he said.

Much of the damage was from fast-flowing floodwaters racing down the steep hillsides surrounding the Valley and rampaging through streets and roads and railroad bridges. Huge boulders, some nine feet high, rolled along in the floodwaters, crashing through bridge supports and pounding roadbeds.

Planning for what became the Sepulveda Basin was already well under way, and debris dams and catch basins had been built on some mountain slopes by 1938. Nevertheless, in March of that year, a disastrous flood struck the Valley and the rest of Los Angeles, doing more than $40 million in damage and taking 49 lives.

“The floodwaters tore up highways and railroad lines, and all of Los Angeles was isolated, cut off from the rest of the world for two days,” Turhollow said.

A major problem was the Los Angeles River, which then flowed freely through the Valley and across the Los Angeles Basin to the ocean. Since the river came and went with the rains, drying up most of the time, it tended to carve new loops and channels with each reappearance, leaving one channel without warning and flowing through what had become populated areas.

By the time work began on the Sepulveda Dam, it had been decided that the river had to be fixed in place by lining a channel with concrete.

The Corps of Engineers has calculated that the dam and the related flood-control system have kept damage in the Los Angeles area to only 10% of what it would be without them.