The Big Thompson Flood: Colorado's Worst Natural Disaster
As with any event of such magnitude and emotional intensity, there are many conflicting "facts" and I have tried to choose those that appear most accurate. Some of it I remember from personal experience, though I was not in the canyon that night. (For my own account, see the article for July 22, 2003.) I have read that the probability of a flash flood like that one is only once in 300 years, or once in 10,000 years, and I don't know if either one is accurate, but here are the elements that came together to create Colorado's worst natural disaster.
The Terrain
The Big Thompson River has its beginning from snow fields on the eastern side of the Continental Divide in Rocky Mountain National Park. It's rivulets cascade down a spectacular array of 12,000 foot peaks into Forest Canyon and a beautiful little river winds through the meadows and wetlands of Morraine Park. Fed by other tributaries, it flows through the town of Estes Park onto Lake Estes, where it is controlled by Olympus Dam. Below the dam the river drops a little more than 2100 feet through the Big Thompson Canyon over 25 miles to the city of Loveland and on east to join the South Platte River. A north fork of the river curves around and enters the main stem at the small community of Drake, about half way down the canyon. Colorado Highway 34 also runs through the canyon. For two miles at the mouth of the canyon, the river and the road wind between the spectacular cliffs of the Narrows. Back in the days before the flood, the road ran right along the canyon floor next to the river.
The People
It happened on July 31, 1976, in the middle of Colorado's Centennial celebration - a three day weekend when the canyon was filled with tourists and residents. Between 2500 and 3500 people were in the canyon, filling motels and camping spaces, relaxing in their summer retreats or retirement homes. The canyon is not wide anywhere along its length so everyone was close to the river. People were coming and going from Estes Park and Rocky Mountain National Park.
The Storm
There have been flash floods in the canyon before, but the flood of July 31, 1976 was something entirely different. I will try to summarize information later reported by the National Weather Service and the National Oceanic and Atmospheric Association (NOAA).
- Early in the morning, an unusually large amount of moisture in the atmosphere east of the mountains was reported, along with very slow movement of the system.
- This highly moist air pushed upslope against the mountains by a polar front, creating a temperature inversion, and a thunderhead began rising, eventually topping at about 60,000 feet.
- Usually, the prevailing winds from the west push storms to the east away from the mountains, but a moist low pressure system had moved in across the Continental Divide from the southwest and it lacked the power to move this storm.
- Instead, it added to the storm by pushing smaller cells from the southwest into the storm.
- The base of the storm clouds was at ground level.
This storm stalled over the Big Thompson Canyon and just to the north of it for more than four hours. During this time, 10"-14" of rain fell on the area, an amount equal to a whole year of normal precipitation. The river began rising unbelievably fast just below Olympus Dam as every small stream and dry wash filled with water from the moisture laden clouds. Lightning was intense, flashing through the black clouds from side to side and striking all around, while thunder rolled continuously. And the rain! It fell in sheets, in pounding torrents strong enough to be painful to fleeing survivors.
The Flood
Water rose so fast! A woman helping to move some guinea hens to higher ground found water around her ankles and then, as she ran toward safety, it was up to her waist. Others were bowled over suddenly when a huge wave of water struck them. People in cars were isolated when mud slides and trees blocked their way and chunks of highway crumbled away into the torrent of water and debris. Many of them climbed the steep hillside, clinging to boulders and trees, finding strength they didn't know they possessed to claw their way higher. In places, the mud was so wet it was liquefied and they slid backwards and had to pull themselves back up. Families climbed with terrified children and others pushed and pulled older and fragile parents and friends.
Those who were trapped in cars drowned as their vehicles were carried away. People who were trapped in houses and motels clung to mattresses that floated them up as the water rose higher and higher, and some of them broke holes in the ceiling to climb into attic crawl spaces. There, they huddled around a brick chimney in the hope it would remain standing while the rest of the building fell apart. Huge trees crashed through walls, sometimes lodging there, sometimes crashing out the other side. A few had enough headroom left to hold on through the night; a few did not.
Watchers on the hillsides were horrified to see cars tumbling through the flood, lights on, tilted crazily against the sky, people trapped inside. Boulders the size of a bus were pushed along by the water, grinding whatever was in their path. The air was thick and sickening with the smell of propane escaping from floating tanks and the crash of thunder was amplified by the sound of tanks exploding as they were thrown against rocks and cars. Pieces of houses and even whole houses were swept through the chaos and now and then the flashing lightning showed a body--human or animal--just part of the debris.
At about 9:40 p.m., when the crest of the flood on the main stem reached the Narrows, most of the traffic had been stopped by Larimer County Sheriff's Deputies who were frantically trying to warn people and rescue anyone they could reach. The ambulance from Loveland had received a call to go into the canyon for an emergency, but had not heard warnings about the crest. With lights and siren going, they ran past the barrier into the Narrows and soon met a 20 foot wall of water that picked the ambulance up and smashed it against the perpendicular rock wall. It held there for a few seconds, long enough for both EMTs to scramble out a window and grab some finger and toe holds on the cliff, then it was torn away and smashed against the opposite canyon wall. They climbed up the sheer face until they found small, precarious ledges where they could cling for the rest of the night.
Two separate crests occurred, for the North Fork deluge traveled further, down through the community of Glen Haven, reaching the main stem at Drake about 40 minutes after the first crest roared through. At the peak of the flood, water raged through the Narrows at 31,200 cubic feet/second, four times the previous flood record.
The storm abated about 2 a.m., though rain continued on into the next day. When a soggy daylight came, the devastation was heartbreaking. In many areas, the highway was gone, Most of the water had raged through, leaving a layer of silt deep enough to completely bury cars and other debris and people. Search and rescue began immediately. In the end, the toll was high: 144 dead, more than 500 injured, 252 homes and 16 businesses totally destroyed, 182 homes and 26 businesses damaged. The eventual cost was estimated at more than $41 million dollars.
Stories of the survivors are dramatic and intense. For these, I have relied on Reflection on the River: The Big Thompson Flood, compiled by Sharlynn Wamsley. It is a collection of stories and pictures written by survivors and relatives and friends of victims. It was published locally by Drake Club Press, P.O. Box 45, Drake, CO, 80515 in 2001 and doesn't appear to be available through any large distributors.
If you are thinking by now that you wouldn't want to spend any time in the Big Thompson Canyon, let me reassure you. When the new road was built, it was raised above the river so that it is improved and much safer. With the weather report improvements I mentioned before, you can safely travel the canyon, fish in the lovely little river that flows through it, and maybe even listen to the beautiful song of a dipper as it flies up and down through the Narrows. Here is a photo I took there just last week. You can barely see a fisherman in the water on the left side of the river.
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