Fifty for 150: 20-foot wall of water crashes down the Big Thompson Canyon in 1976

Big Thompson Canyon embodies the stark beauty of the Colorado mountains. A river rushes through the scenic channel, enclosed on both sides by tree-adorned hills and rock formations. There’s nowhere to go but up on either side.

This story is part of Colorado at 150. Each Fifty for 150 story focuses on an event that helped define Colorado over 150 years of statehood. Newsline is publishing one Fifty for 150 story every weekday in reverse chronological order until the sesquicentennial, Aug. 1, when the final of 50 stories, about the declaration of statehood, will appear.

That’s what made the rains on July 31, 1976, so deadly.

On that day, up to 3,500 visitors had traveled into the canyon as the state prepared to celebrate its centennial the next day. At about 6:30 p.m., the first signs of trouble arose as a thunderstorm gathered overhead.

Atmospheric conditions aligned so that the storm, 60,000 feet high, parked itself near Hague’s Peak over the canyon, and more than a foot of rain is estimated to have collected in just six hours in a stretch of the canyon between Estes Park and Drake. Almost as much rain fell that night as typically would be seen all year in the region.

That massive amount of precipitation raced downhill at about 15 miles an hour in the form of a 20-foot wall of water. For many people in its path, there was no time to get out of the way.

The Big Thompson River flood killed 144 people, making it one of the deadliest natural disasters in state history. Some bodies were recovered 25 miles away. The flood injured 150 people, destroyed hundreds of homes and businesses on the river banks, and washed out U.S. 34.

Community members maintain a Big Thompson Flood memorial, which includes a website.

“Each newscast about floodwaters rising and the brave efforts of emergency responders echoes in the memories of those who survived the catastrophic Big Thompson flood of 1976,” the site says. “For many, these stories serve as a poignant reminder of the night our canyon changed forever — a night that claimed lives, shattered families, and transformed landscapes. While nearly half a century has passed, the legacy of resilience, remembrance, and community remains strong.”

The Loveland Museum plans a 50th anniversary exhibition on the flood. It’s scheduled to open July 31.