A year’s worth of rain in about four hours caused what is normally a year’s worth of deaths nationally from flooding in one night.
But what is even more striking about the July 31, 1976, disaster is how community members and leaders applied their creativity to rebuild the Big Thompson Canyon.
Long after the helicopters left, the water subsided and crews picked up the major debris, those involved forged ahead. It took years before officials rebuilt the highway, water distribution systems, bridges and the city’s hydroelectric plant.
Still today, the county is working to sort out future ownership and maintenance on some of the properties hit hardest by the flood.
The force of the flood washed away or destroyed most of U.S. 34 from below Estes Park to the canyon’s mouth.
Mindy Crane, Colorado Department of Transportation spokeswoman, said in the aftermath workers carved out a temporary road for emergency traffic in 48 days. By Oct. 25, U.S. 34 was opened to the public.
But it would take nearly four years before the winding highway was completely rebuilt.
Using federal highway emergency relief funds, state officials commissioned multiple projects to finish the effort.
Crane said to safeguard against future disasters, contractors raised the highway as much as 15 feet in some areas above the original road. They anchored bridges and precast concrete panels for the retaining wall with steel supports that are deeply embedded in the canyon walls.
To keep floodwaters off the highway, officials also widened the river and added concrete panels in some areas to direct storm waters downstream.
At the entrance of the canyon, the flood tore critical water pipes into inoperable pieces.
The Northern Colorado Water Conservancy District’s steel siphon lay a quarter of a mile downstream from its original position. The 9-foot-wide siphon supplies Western Slope water to Horsetooth Reservoir.
Brian Werner, district spokesman, said while the U.S. Bureau of Reclamation owns the project, the water conservancy district kicked in reserve funds to get it running in a mere 88 days.
“Disasters have a tendency to bring everyone together and work out the details later,” he said. “This was no different.”
In the meantime, district workers installed a pump to keep water flowing in the adjacent Hansen Feeder Canal, which irrigators and residents relied upon.
While the initial responses restored the distribution system, the district experienced flood-related problems for another 20 years. Werner said it took that long to replace the canal’s concrete panels that had buckled from flood seepage.
The cars, propane tanks and boulders hurled down the steep canyon that night also wiped out parts of Loveland’s utilities. The flood left only the turbines from the 1924 hydroelectric plant at Viestenz-Smith Mountain Park. It also knocked out the main line to the water treatment plant and emptied one of the water tanks.
Even so, Ralph Mullinix, Loveland Water and Power director, said at that time, the issue wasn’t water supply but water quality. For two years, city workers had to manually clean out the plant’s head gates, and still, the water was brackish from sediment. This slowed the plant’s production.
With ongoing road construction and unsettled banks, each new rainstorm brought down rocks, branches and dirt to the plant for several more years.
“It wasn’t a here today and gone tomorrow,” he said. “The amount of debris that was in the canyon and continued to come down from those hills was unbelievable.”
Mullinix said to avoid a flood replay, he designed water lines that don’t cross the river. In 1977, the Loveland City Council approved building a backup supply, Green Ridge Glade Reservoir. And Federal Disaster Assistance Administration dollars paid to reconstruct the hydroelectric plant further back from the bank.
For some, the cleanup and rebuilding effort reverberates even today.
Larimer County still is sorting through how to sell or maintain the 153 canyon parcels it bought in the flood’s wake, said Gary Buffington, county parks and open lands director.
In 1978, the county purchased properties that a board determined were not buildable, using $1.7 million in National Park Service conservation funds.
Since then, some parcels were consolidated and turned into four canyon parks: The Narrows, Sleepy Hollow, The Forks and Glade Park. Now, the county is considering using six sites as recreational pull-offs and selling about 60 lots.
Current and former canyon residents would get the first pick, Buffington said.
“This process has taken a while, which is fine with me,” he said. “It gives people a chance to feel good about it and ask questions.”
He added, “It’s a pretty emotional issue for some of those residents in the canyon.”
Shar Wamsley, a canyon resident and daughter of a flood survivor, said many property owners believed the rulings on who could rebuild were subjective.
“They felt the damage wasn’t as severe as the prognosis was,” she said. “The county cleaned up very fast, and many didn’t have time to rebuild.”
Even so, she said about half of the residents and a number of businesses, such as the Big Thompson Indian Village and Loveland Heights Cottages, stayed and built again. The flood could not wipe away the willpower of many who desired to stay.
“They’re a hardy group,” she said. “They do well in recovery from these types of situations.”
Rex Burns, Larimer County senior engineer, said those who could, had to build on higher ground and use additional fill dirt outside of their structures to buffer against future floods. Riverbanks were also armored with layers of filter cloth and rocks to provide extra stability.
The county formed an improvement district to reconstruct 23 concrete bridges for property owners. In a flood, the bridges will collapse instead of blocking debris and water.
Burns said the flood has changed the way he, as an engineer, perceives building in a flood way.
“What we’ve found is that boundaries are never rigid,” he said. “Sediment moves in the water, and half of the damage is caused by what’s in the water.”