Hard to imagine today — with climate change and record drought in California — but 77 years ago, two massive storm systems broke annual rainfall records — in the course of 5 days — killing 115 people, and destroying anything in the path of the untamed LA river.

Countless lives lost, thousands of homes destroyed, entire roads and bridges wiped out. As Los Angeles developed and population grew along the banks of the LA River, controlling the flood waters became a necessity. After the historic floods of 1914, 1934 — and the catastrophic flood of 1938, public outcry for flood control reached fever pitch. Without the technology to study the environmental impact of entombing the natural riverbed in cement, plans were laid by the Army Corps of Engineers to channelize the unpredictable LA river.

The new channel was put to the test in 1969 with 13 inches of rain in 9 days. A success, by flood control standards, but the devastating effects to the ecology wouldn’t be recognized for dozens of years. By 1985, environmentalists were calling for restoration. In 2014, the Army Corps of Engineers reversed course and recommended the most expensive and comprehensive plan studied to restore 11 miles of the LA River. 

LA River Channelization Facts:

• 20 years to complete
• 20 million cubic yards of earth moved
• 3.5 million barrels of cement poured
• 147 million pounds of reinforced steel
• More than 300 bridges constructed

Relevent links:

Los Angeles Flood of 1938: Cementing the River’s Future

Los Angeles River: From Concrete Ditch to Urban Oasis