Big Thompson River
The Big Thompson River is a tributary of the South Platte River, approximately long, in the U.S. state of Colorado. Originating in Forest Canyon in Rocky Mountain National Park, the river flows into Lake Estes in the town of Estes Park and then through Big Thompson Canyon. It includes four crossings/bridges which are listed on the U.S. National Register of Historic Places.
Course of the river
The headwaters of the Big Thompson River begin in Forest Canyon within Rocky Mountain National Park in Larimer County, Colorado. The river flows east through Moraine Park to the town of Estes Park. There it is held in Lake Estes by Olympus Dam before being released into the Big Thompson Canyon. The North Fork Big Thompson River also begins in Rocky Mountain National Park, on the northern slopes of the Mummy Range. This tributary flows east, through the town of Glen Haven, where it merges with the Big Thompson River in the town of Drake, in the Big Thompson Canyon.From Lake Estes, the river descends in elevation through the mountains in the spectacular Big Thompson Canyon, emerging from the foothills west of Loveland. It flows eastward, south of Loveland across the plains into Weld County and joins the South Platte approximately south of Greeley. It receives the Little Thompson River approximately upstream from its mouth.
Water resources in the Big Thompson River are managed by the Northern Colorado Water Conservancy District as part of the Colorado-Big Thompson Project.
1976 flood
On July 31, 1976, during the celebration of Colorado's centennial, the Big Thompson Canyon was the site of a devastating flash flood that swept down the steep and narrow canyon, claiming the lives of 143 people, 5 of whom were never found, making it the deadliest disaster in Colorado's history. This flood was triggered by a nearly stationary thunderstorm near the upper section of the canyon that dumped of rain in less than 4 hours. 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 high raced down the canyon at about, destroying 400 cars, 418 houses and 52 businesses and washing out most of U.S. Route 34. This flood was more than 4 times as strong as any in the 112-year record available in 1976, with a discharge of 35,000 cubic feet per second.
In 2008, a man who was thought to have died in the flood was found to be alive and living in Oklahoma. Darrell Johnson and his family had rented a cabin east of Estes Park, but left without telling anyone on the morning of July 31. A woman who was researching the flood's victims discovered he was still alive.