Worst Floods in California History

The old song says "it never rains in California" — but that's not necessarily true.

California has a well-earned reputation for its “endless summer” climate, particularly in the southern part of the state. But as we’ve seen in recent years, the Golden State has its share of extreme weather, which will only get more extreme as climate change worsens.

These are the worst floods in California’s history. And scientists believe there are bigger storms on the horizon.

The Flood of 1605

Wikipedia

California is no stranger to megastorms. In fact, they happen in the Golden State every few hundred years. Scientists, after studying sediment, found evidence of these ARkStorms in 212, 440, 603, 1029, 1418 and 1605 AD.

The most recent ARkStorm in 1605 submerged large portions of present-day California.The indigenous peoples of the land were greatly affected. Sediment shows the storm deposited a two-inch thick layer of silt in the Santa Barbara basin alone.

Scientists believe the flood of 1605 to be the worst flood in the state in the past 2,000 years.

The Great Flood of 1862

Wikipedia

The closest California has come to a megaflood in post-Industrial Revolution America was in 1861-1862. The storm started on Christmas Eve and lasted a whopping 43 days. It transformed rivers running down from the Sierra Nevada mountains into raging torrents that swept away entire communities.

The state’s Central Valley became an inland sea that was 300 miles long and 20 miles wide. Tens of thousands of people lost their lives, as did the state’s cattle. California turned from a cattle state to a citrus and agricultural state after the storm.

Downtown Sacramento caught the brunt of it. California’s capital was submerged under 10 feet of debris-filled water. The city was so damaged that its legislature moved to San Francisco for six months. When it was over, the state was bankrupt.

St. Francis Dam Disaster

San Francisquito Canyon after St. Francis Dam collapse

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Not all floods are natural occurrences. Some are man-made, like the St. Francis Dam disaster of 1928.

On March 12 of that year, the concrete dam — located in the San Francisquito Canyon near Los Angeles — failed just before midnight. Over 55 miles of violent flooding killed more than 450 people and caused widespread damage across the city. Debris and bodies were found as far away as Catalina.

The dam’s foundation of weak, unstable rock, and its shoddy design and construction caused its structural failure and eventual collapse. The failure of St. Francis Dam was one of the worst civil engineering disasters in the country during the 20th century. However, the horrific event led to changes in dam design and construction and increased scrutiny of already existing dams around the country.

Remnants of the disaster can still be seen in the San Francisquito Canyon today.

The Crescenta Valley Flood

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Los Angeles County’s Crescenta Valley lies between the San Gabriel Mountains, the Verdugo Mountains and the San Rafael Hills and is home to La Cañada Flintridge, portions of Glendale, Montrose, Sunland, and Tujunga, which are all very populated today.

In 1933 and 1934, heavy rainfall overwhelmed the area’s drainage systems. This flood was particularly severe, causing significant damage to structures and infrastructure and the deaths of dozens of people

The flood was a result of the area’s topography and the lack of a real flood control system. The Crescenta Valley is narrow and surrounded by steep hills and mountains, which makes it particularly susceptible to flooding, even today.

After the disaster, local authorities took steps to mitigate future disasters by building a comprehensive system of dams and levees and improving the county’s drainage systems.

Los Angeles Flood of 1938

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If you’ve ever wondered how the Los Angeles River came to be walled in by concrete, it was primarily due to the Los Angeles flood of 1938, which occurred on March 2-4 of that year and another significant (but smaller) storm the month before.

Even before that, as Los Angeles grew, people built homes closer and closer to the river’s banks, which would often spell danger for those homeowners, as the river would grow into a raging torrent with just a few hours of rainfall.

The 1938 storm caused heavy rainfall and strong winds. This, in turn, caused widespread flooding and landslides. Homes, businesses, and the city’s infrastructure were significantly damaged, and at least 115 people died.

That year, the Army Corps of Engineers began walling in the river to create a flood control channel.

Christmas Flood of 1964

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The Christmas flood of 1964 affected three states — California, Oregon and Nevada. The heavy precipitation it brought to the region quickly overwhelmed drainage systems, causing widespread flooding.

In California, Sacramento and the San Joaquin Valley were the areas most affected. At least 50 people died in the storm. Homes, businesses, and infrastructure were damaged, and it is considered one of the worst natural disasters in the history of all three states.

The Ocotillo Flash Flood

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It’s rare, but even the Pacific Ocean has the occasional hurricane. In September 1976, Hurricane Kathleen dropped nearly a foot of water in the mountains near San Diego overnight.

The next day, a 40-foot wall of water came down the mountain canyon and flooded Ocotillo in California’s Imperial Valley. Nearly 80 percent of Ocotllio was destroyed, and six people drowned.

A quarter mile of Interstate 8 and a 60-foot bridge were also destroyed by the desert flood.

The Merced River Flood

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The January 1997 Merced River Flood was devastating to the Yosemite Valley in Mariposa County’s Yosemite National Park and is said to be one of the park’s worst ever natural disasters.

Over the New Year, the flood stranded 2,100 visitors in the park. When they were finally able to begin leaving the area, all roads out of the park — Highway 120, Highway 41, and Highway 140 —were under water.

While there were no fatalities, much of the area was destroyed, including half of all accommodations.

Los Angeles County Flood of 2005

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The Los Angeles flood of January 2005 was the largest since 1938 and affected many of the communities surrounding the river. It was far-reaching in its damage. Areas ranging from Santa Barbara County to San Diego County, Riverside and San Bernardino were also affected.

Near 40 inches of rain was recorded in downtown Los Angeles for the season — the most rain since 1884. From December 27, 2004, through January 10, 2005, 16.97 inches of rain fell in the area, causing damages to homes and infrastructure.

More than 10 people died as a result of the storm.

2022-2023 California Floods

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The state’s years-long drought isn’t exactly over, but the storms of 2022-2023 have put an unanticipated dent in it. Flooding affected the entire state as a result of multiple atmospheric rivers, which caused extended periods of heavy rainfall.

The floods are said to have been exacerbated by climate change, as weather extremes are becoming increasingly common.

Due to these storms, there have been at least 19 fatalities thus far.