The Forgotten New Year’s Flood of 1934 Reshaped Los Angeles
A forgotten New Year’s disaster killed dozens, swept hundreds of homes off their foundations in the foothills, and forced California to invent the modern playbook for flood control.
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New Year’s Eve floodwaters. (LA Times)
Just after midnight on New Year’s Day, 1934, a wall of mud, boulders and water came roaring out of the San Gabriel Mountains into the foothill towns of La Crescenta and Montrose. By morning, more than 400 homes were destroyed and dozens of people were dead. The Los Angeles flood of 1934, also called the Crescenta Valley flood, is mostly forgotten now outside the area it hit. But it was one of the deadliest floods in Los Angeles history, and it helped create the concrete flood-control system that still defines the city.
It started with rain, a lot of it, in the last days of 1933. The storms were probably what we’d now call an atmospheric river, a long plume of moisture from the Pacific aimed straight at Southern California. The rain hammered the steep front of the San Gabriel Mountains.
Nearly 12 inches fell on the foothills in just a few days. And the slopes above La Crescenta were especially vulnerable, because a wildfire had burned off the chaparral just weeks earlier, in November 1933. Burned hillsides can’t soak up water or hold soil in place. That’s still the recipe for disaster in Southern California: fire in the fall, heavy rain in the winter. When the ground finally gave way, mud, rock and water poured down the canyons and straight into the neighborhoods below.
A worker digs out a car and the remains of a home on Glenada Ave. in Montrose. (LA Times)
La Crescenta and Montrose took the worst of it. Houses were knocked off their foundations. Boulders the size of cars rolled down residential streets, crushing whatever was in the way. Mud piled up several feet deep, burying cars and filling homes, and power lines and bridges went down, leaving the towns cut off and in the dark. Some families were swept right out of their houses. More than 400 homes were destroyed, and dozens of people were killed.
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The worst single tragedy was at American Legion Post 288, where about a dozen people had taken shelter, thinking it was safe. The hall sat right in the path of a debris flow coming out of Pickens Canyon. It smashed through the walls and filled the building with mud, killing the people inside. Today, a small memorial overlooks the site, which is now part of the flood control system.
American Legion Hall damaged by flood and mudslide, La Crescenta-Montrose, 1934 (LA Times)
The disaster was a wake-up call. Los Angeles was spreading fast, with new neighborhoods climbing right up to the base of the mountains. Then, in 1938, an even bigger flood hit the whole region. Together, the two floods convinced the public and the government that the region needed serious flood control. Los Angeles County built debris basins at the mouths of foothill canyons, including Pickens Canyon, to catch mud and boulders before they reached homes. Dams and basins went up in the mountains, and the Army Corps of Engineers lined the Los Angeles River with concrete, turning a wandering, unpredictable river into the giant concrete channel you see today, built to rush storm water out to the ocean. The Arroyo Seco and other streams got the same treatment.
People survey the damage to their cars and roads in the aftermath of the flood. (LA Times)
It mostly worked. Nothing like the 1934 disaster has happened there since. But critics say all that concrete cut Los Angeles off from its rivers, wiped out wildlife habitat and sent rain that could have recharged groundwater straight out to sea. Lately, the thinking has shifted toward softer approaches, like restoring stretches of the Los Angeles River with parks and habitat and building basins that hold storm water while doubling as green space.
Mud, rocks, and wrecked cars littered Montrose Avenue in Montrose after the New Year’s flooding. (LA Times)
With climate change bringing bigger storms, Los Angeles is rethinking its flood system again. City and county plans for the Los Angeles River aim to turn parts of the concrete channel back into something more like a living river, with parks, trails and wildlife habitat along its 51 miles. The hard part is doing it without making flooding worse, and it’ll cost billions.
Rendering of a section of the LA River part of the Los Angeles River Revitalization Master Plan (Wenk Associates)
The lesson of 1934 still applies. Fire, then heavy rain, then debris flows: it happened in Montecito in 2018, when mudslides after the Thomas Fire killed 23 people, and it will happen again. Every time a big fire burns the hills above a Southern California town, people who know this history start watching the winter forecast.
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