On This Day 47 Years Ago Colorado Experienced One of Its Worst Natural Disasters, The Big Thompson Flood

By Shawn Patrick on August 1, 2023
Denver Post via Getty Images

August 1st is normally thought of as a pretty happy day in Colorado. After all, it is the day we celebrate our state’s birthday, the day we earned our statehood. However, it’s also one of the saddest days in our state’s history too. 

According to the United States Geological Survey, the Big Thompson flood became one of the state‚Äôs deadliest and costliest disasters.

It was supposed to be a year of monument for the state that was celebrating it’s 100th birthday, instead 1976 will be forever tied to one of the worst natural disasters in Colorado’s history. The Big Thompson Canyon was the site of a devastating flash flood that swept down the steep and narrow canyon, claiming the lives of 144 people, 5 of whom were never found. This flood was triggered by a nearly stationary thunderstorm near the upper section of the canyon that dumped 12 inches of rain in less than 4 hours (more than 3/4 of the average annual rainfall for the area). Little rain fell over the lower section of the canyon, where many of the victims were.

Around 9 p.m., a wall of water more than 20 feet high raced down the canyon at about 14 miles per hour, destroying 418 homes, 52 businesses, numerous bridges, paved and unpaved roads and power and telephone lines. U.S. 34 was washed out as 10-foot-wide boulders were carried down the river.

Damages cost an estimated $39 million.

A memorial was installed in 2001 to mark the 25th anniversary of the flood. It’s about 10 minutes west of Loveland, about one mile from Drake.


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