If you’ve ever wondered what compelled Southern California to so thoroughly re-engineer its hydrology – why it dammed its mountain streams, buried its flatland creeks as storm drains, and paved its rivers into concrete channels – the photographs below provide a succinct and sobering answer. Though the floodwaters of 1938 were not the highest in the region’s recorded history (those came with the truly Noachian deluge of 1861-62), they were by far the most destructive, coming as they did after decades of questionable development on flood plains had put lives and property in jeopardy.

On Feb. 27, 1938, the rain started falling and did not stop for five days. Eleven inches fell on downtown Los Angeles and up to 32 inches in the San Gabriel Mountains, swelling the normally tame streams of the Los Angeles Basin into foaming torrents. Five people died in North Hollywood when the Lankershim Boulevard bridge collapsed into the Los Angeles River. Ten more perished in Long Beach when a pedestrian bridge near the river’s mouth gave way. At several points along Foothill Boulevard (Route 66) in the San Gabriel and Pomona valleys, creeks issuing from the mountains washed away pieces of the national highway.

Many watercourses made quick work of the flood control structures that, against the streams' natural inclination to wander across flood plains, sought to confine them to a narrow channel. In the southeastern San Fernando Valley, for instance, the Los Angeles River overtopped its levee and cut new bends near Griffith Park, destroying several buildings on the Warner Bros. studio lot. And even where the flood control structures held, they tended to exacerbate the flooding; as rain fell on newly developed and hence recently paved land, the levees blocked runoff from reaching their outlet to the sea, inundating residential neighborhoods and industrial areas adjacent to the rivers.

Anaheim houses surrounded by floodwaters from the Santa Ana River on March 3, 1938. Photo by Watson Airfotos, courtesy of the Anaheim Public Library photograph collection on Anaheim local history.

No watercourse became so enraged as the Santa Ana River, which drained the largest watershed of all the Los Angeles Basin's rivers. On the morning of March 3, the river overtopped a levee at the Yorba Bridge near Santa Ana Canyon. As the dike fell, an eight-foot wall of water roared downstream, smashing railroad bridges and carrying houses off their foundations and into orange groves. The greatest loss of life came in the Anaheim-area barrios of Atwood and La Jolla, where 43 perished. La Jolla resident Eddie Castro, who took refuge with his family in the community’s brick schoolhouse, listened as the raging waters tore apart his neighbors’ houses. “It sounded like real large squeaks and scratches, cracks, and booms,” he recalled in oral history now preserved at the Center for Oral and Public History at Cal State Fullerton. “All was very quiet. It seemed like we were just waiting to hear the next crash.”

Similarly apocalyptic scenery abounded. Two of the Los Angeles Alligator Farm’s namesake animals escaped into the flood waters. Storm waters snapped the transmission lines from Hoover Dam, triggering blackouts. At Ninth Street, a gas main ruptured beneath the Los Angeles River and ignited, and for a time it appeared that the river itself was burning. In the midst of this chaos, Los Angeles found itself isolated as swollen streams severed all its connections to the outside world: highway, railroad, telephone, telegraph.

When the waters finally receded, 87 people had died, property losses topped $1.3 billion (in 2017 dollars), and Southern California resolved to prevent another cataclysm. Within a few years, and with the backing of local leaders, the U.S. Army Corps of Engineers had shackled the untrustworthy Santa Ana and San Gabriel rivers with dams and slipped the Los Angeles River into its concrete straitjacket.

Anaheim & Vicinity

Anaheim during the flood of 1938. Photo by Watson Airfotos, courtesy of the ​​Anaheim Public Library photograph collection on Anaheim local history.

Aerial view looking west of the Santa Ana River on March 10, 1938, a few days after the flood. The town of Anaheim is visible at top-left. Photo by Watson Airfotos, courtesy of the Anaheim Public Library photograph collection on Anaheim local history.

Downtown Anaheim on March 3, 1938. Photo courtesy of the Anaheim Public Library photograph collection on Anaheim local history.

A flooded Grand Avenue in Buena Park. Photo courtesy of the Orange County Archives.

In Orange County, the Santa Ana River claimed nearly all the bridges that crossed it. Photo courtesy of the USC Libraries – California Historical Society Collection.

Highway 14 crossing the Santa Ana River. Photo courtesy of the USC Libraries – California Historical Society Collection.

North Hollywood & Burbank

Aerial view of rushing flood waters in North Hollywood, courtesy of the Los Angeles Times Photographic Archive. Department of Special Collections, Charles E. Young Research Library, UCLA.

Houses caught in a flooded Tujunga Wash. Photo courtesy of the USC Libraries – California Historical Society Collection.

Flooded houses and farms in North Hollywood. Photo courtesy of the Los Angeles Times Photographic Archive. Department of Special Collections, Charles E. Young Research Library, UCLA.

Aerial view of the confluence of the Los Angeles River and Tujunga Wash after the flood, courtesy of the San Fernando Valley History Digital Library, California State University, Northridge University Library.

Aerial view of the Los Angeles River at Victory Blvd., courtesy of the San Fernando Valley History Digital Library, California State University, Northridge University Library.

The swollen Los Angeles River claimed the Barham Bridge and several structures on the Warner Bros. studio lot in Burbank. Photo courtesy of the USC Libraries – California Historical Society Collection.

A person walks in the riverbed near a collapsed bridge in North Hollywood. Photo courtesy of the Herman J. Schultheis Collection – Los Angeles Public Library.

San Gabriel and Pomona Valleys

A flooded San Gabriel River in Azusa, showing the collapsed San Gabriel Railroad Bridge. Photo courtesy of the USC Libraries – California Historical Society Collection.

A swollen Big Santa Anita Creek in Monrovia. Photo courtesy of the USC Libraries – California Historical Society Collection.

Elsewhere

The Bardsdale Bridge over the Santa Clara River during the flood of 1938. Photo courtesy of the California State Library.

An "over-flooded" Dominguez Slough. Photo courtesy of the Rancho San Pedro Collection, CSUDH Archives.

The collapsed Dayton Avenue Bridge in Los Angeles. Photo courtesy of the Herman J. Schultheis Collection – Los Angeles Public Library.