Structures in the Acton area are lost as the banks of the Santa Clara River crumble,
probably in the flood of March 2, 1938.
Surpassing the St. Francis Flood of 1928 in scope — if not in deaths — the Great Flood (aka Los Angeles Flood) of 1938 hit the greater Los Angeles area hardest overnight on March 1-2. By the time the water receded, 5,601 buildings had been destroyed and 113 to 115 Southland residents were killed.
Considered a 50-year flood, it started Feb. 27, 1938, when a storm system moved in from the Pacific Ocean and hit the San Gabriel Mountains. The region was soaked with continual rainfall that caused only routine flooding until a second storm came on the heels of the first. Driven by gale-force winds, it hit March 1 at about 8:45 p.m., dumping 10 inches of rain in the lowlands and at least 32 inches in the mountains. Almost every vacation resort in the San Gabriels washed away; most were never rebuilt (see Robinson 1977).
The Santa Clarita Valley wasn't spared. The Santa Clara River overflowed. Roads and bridges were wiped out and ranch buildings situated along the riverbank floated away. (Note to current residents: The Santa Clara River might look dry most of the year, but watch out when it rains. It's prone to flash flooding. Stay away.)
As hard as Los Angeles County got hit, Orange and Riverside counties actually sustained more damage because they lacked the kind of flood-control system L.A. had with the Santa Ana River system. (The Santa Ana, Los Angeles and San Gabriel rivers overflowed, too.) But Los Angeles was far more populated; Orange and Riverside counties were largely agricultural.
In response to the 1938 flood, Congress passed the Flood Control Act of 1941, which authorized the U.S. Army Corps of Engineers to channelize the Los Angeles River and parts of the Santa Ana.
And that's why the L.A. River is a concrete flood-control channel instead of the wild-flowing river it once was.
— Leon Worden 2013