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Remembering the 1976 Big Thompson Canyon flood

Posted: 2:48 PM, Jul 31, 2022
Updated: 2023-11-08 11:24:42-05
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DENVER — Sunday marks the 46th anniversary of the Big Thompson Canyon flood, which claimed the lives of 144 people and earned the unfortunate title of the one of the deadliest flash floods in Colorado history.

On July 31, 1976, an estimated 2,500 – 3,500 people were inside homes, cars or enjoying the outdoors in Big Thompson Canyon in Larimer County when the skies opened up that evening, dropping large volumes of water down the slopes and the canyon floor.

Many had little to no warning when a 20-foot “wall” of water swept through the canyon that evening. Of the 144 people who lost lives that day, it is estimated five were never found.

One of those five was friends with Tina Anderson, who had just turned nine when the flood hit. After finding high ground, she said her parents did everything they could to protect their children from what was happening around them.

The deadliest flash flood in Colorado history

“They kept talking to us to keep us from hearing what they were hearing. And later realizing those were cries of people in vehicles going down the river," Tina recalled. "The only way that I can explain it was as a child, my visual of a war zone. Nothing was where it was supposed to be.”

Tina's mother Barbara was instrumental in constructing a memorial for the lives lost outside of Drake.

“It'll always be part of our lives," said Barbara. “If you can't remember the past, the future hasn't got much for you.”

Deborah Watts survived the flood, but her three year old son was killed by the waters. Watts was also injured badly in the chaos and did not think she would survive.

“It's honestly, it's amazing that I survived it," Watts said.

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When the water receded, Mother Nature’s destructive power was on full display. The flood destroyed more than 400 homes and businesses. Four hundred cars were also destroyed, and US 34 was nearly completely washed out.

According to the National Weather Service, around 6:30 p.m. that day, a storm front stalled over the central portion of the Big Thompson River watershed. Very heavy rain began falling over the area and didn’t let up until around 11 p.m.


During the 4 ½ hour long deluge, more than 12 inches fell in some parts, causing Big Thompson River to run at an estimated 31,200 cubic feet per second at the mouth of the canyon, according to a National Oceanic and Atmospheric report.

That report was commissioned to assess the effectiveness of the warning system. The NOAA report commended the actions of a radar operator stationed in Limon for the information he conveyed to operators in Denver. However, it found several failings in the system due to equipment issues, radar discrepancies, and staff shortages.

Do you remember the 1976 Big Thompson Canyon flood?

The flash flood warning was issued too late, at 11 p.m. The report blames the uncertainty as to what was actually happening on the ground due to ground observers not answering phone calls, among other issues, because phone service was knocked out in the canyon.

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Figure 13. Enlargement of enhanced infrared imagery over Colorado for 7:00 p.m. on July 31, 1976 with enhancement curve CB. Note the explosive growth that has occurred in Area A during the past half hour over the Big Thompson Basin.

Since then, several flash floods have impacted the area, but none as tragic as the 1976 flood. In September 2013, a massive flooding event tore through the canyon and many other parts of the Front Range and Eastern Plains.

The 2013 flood affected 14 counties, killed 10 people, damaged 26,000 homes, and entirely destroyed 2,000 homes, according to the United States Department of Agriculture.

Every year, survivors of the 1976 Big Thompson Flood gather at a memorial plaque near Drake to remember those who lost their lives. However, this year was modified because of Barbara's health.