Big Thompson Flood
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The Big Thompson River is a
tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...
of the
South Platte River The South Platte River is one of the two principal tributaries of the Platte River. Flowing through the U.S. states of Colorado and Nebraska, it is itself a major river of the American Midwestern United States, Midwest and the American Sou ...
, approximately long, in the U.S. state of
Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...
. Originating in Forest Canyon in
Rocky Mountain National Park Rocky Mountain National Park is a List of national parks of the United States, national park of the United States located approximately northwest of Denver in north-central Colorado, within the Front Range of the Rocky Mountains. The park is s ...
, the river flows into
Lake Estes Lake Estes is a reservoir in Estes Park, Colorado created by Olympus Dam. The lake has a shoreline of about and a surface area of . The reservoir lies on the Big Thompson River and is a component of the Colorado-Big Thompson Project. Lake Est ...
in the town of
Estes Park Estes Park () is a List of municipalities in Colorado#Statutory town, statutory town in Larimer County, Colorado, United States. The town population was 5,904 at the 2020 United States census. Estes Park is a part of the Fort Collins, CO Metropo ...
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 Rocky Mountain National Park is a List of national parks of the United States, national park of the United States located approximately northwest of Denver in north-central Colorado, within the Front Range of the Rocky Mountains. The park is s ...
in
Larimer County, Colorado Larimer County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 359,066. The county seat and most populous city is Fort Collins. The county was named for William Larimer, Jr., the founder of Denve ...
. The river flows east through Moraine Park to the town of
Estes Park Estes Park () is a List of municipalities in Colorado#Statutory town, statutory town in Larimer County, Colorado, United States. The town population was 5,904 at the 2020 United States census. Estes Park is a part of the Fort Collins, CO Metropo ...
. There it is held in
Lake Estes Lake Estes is a reservoir in Estes Park, Colorado created by Olympus Dam. The lake has a shoreline of about and a surface area of . The reservoir lies on the Big Thompson River and is a component of the Colorado-Big Thompson Project. Lake Est ...
by
Olympus Dam Olympus Dam is a dam located on the Big Thompson River, in the town of Estes Park, Colorado. The reservoir behind the dam, Lake Estes, is the main source of drinking water for Estes Park. The dam was constructed between 1947 and 1949. The dam i ...
before being released into the Big Thompson Canyon. The
North Fork Big Thompson River The North Fork Big Thompson River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed March 25, 2011 tributary of the Big Thompson River in Larimer County, Colorado. The river's source i ...
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 Drake may refer to: Animals and creatures * A male duck * Drake (mythology), a term related to and often synonymous with dragon People and fictional characters * Drake (surname), a list of people and fictional characters with the family ...
, 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 In geography, a plain, commonly known as flatland, is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, an ...
into Weld County and joins the
South Platte The South Platte River is one of the two principal tributaries of the Platte River. Flowing through the U.S. states of Colorado and Nebraska, it is itself a major river of the American Midwest and the American Southwest/ Mountain West. I ...
approximately south of Greeley. It receives the
Little Thompson River The Little Thompson River is a tributary of the Big Thompson River and thence the South Platte River in the U.S. state of Colorado. The river's headwaters lie in the Roosevelt National Forest. It flows east through the foothills of the Rocky M ...
approximately upstream from its mouth. Water resources in the Big Thompson River are managed by the
Northern Colorado Water Conservancy District The Northern Colorado Water Conservancy District — more commonly referred to as Northern Water — is a water utility for eight counties in northeastern Colorado. Northern Water works with the Colorado-Big Thompson Project to transfer water fr ...
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 A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice and snow. Flash f ...
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 A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustics, acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorm ...
near the upper section of the canyon that dumped of rain in less than 4 hours (more than 3/4 of the average annual rainfall for the area). 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 U.S. Route 34 (US 34) is an east–west United States highway that runs for from north-central Colorado to the western suburbs of Chicago. Through Rocky Mountain National Park it is known as the Trail Ridge Road where it reaches an elevati ...
. This flood was more than 4 times as strong as any in the 112-year record available in 1976, with a discharge of 1,000 cubic meters per second (35,000 ft³/s). In 2008, a man who was thought to have died in the flood was found to be alive and living in Oklahoma. Daryle 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.Flood 'Victim' Found Alive 32 Years Later
, TheDenverChannel.com. 2008.


2013 flood

The canyon was just one of the many areas along the Front Range that were devastated in the September 2013 flood. While not as intense as the 1976 flood, the storms that caused the flooding in 2013 still sent enough water down the canyon to wash out the highway in many places. The flood also damaged the US Bureau of Reclamation's Dille Diversion Dam. The biggest infrastructure casualty, however, was the City of Loveland's hydroelectric plant (rebuilt after the 1976 flood); the Idylwilde Reservoir was completely filled with silt and rocks, the Idylwilde Dam broke free of the bedrock, and the hydroelectric plant in the Viestenz-Smith Mountain Park was filled with water and silt. The dam was in the process of being relicensed with the FERC, but it was instead demolished, the dam material and contents of the reservoir being used as fill for highway repairs. The park has since been redone to accommodate the post-flood river channel and to harden it against potential future floods. The city also rebuilt its municipal electric distribution line into the canyon to replace the original 1925 transmission line and remove obsolete distribution equipment.


See also

* Big Thompson River Bridges, four crossings that were listed on the
National Register of Historic Places The National Register of Historic Places (NRHP) is the Federal government of the United States, United States federal government's official United States National Register of Historic Places listings, list of sites, buildings, structures, Hist ...
*
List of Colorado rivers This is a list of rivers and streams in the U.S. State of Colorado. # Alphabetical list # Tributary chart __TOC__ Alphabetical list The following alphabetical list includes many important streams that flow through the State of Colorado, includin ...


References


External links


I Dream of Genealogy Memorial for Big Thompson Canyon Flood Victims of 1976



Colorado State University: Big Thompson Watershed

Northern Colorado Water Conservancy District


{{Authority control Tributaries of the Platte River Rivers of Larimer County, Colorado Rivers of Weld County, Colorado 1970s floods in the United States 1970s floods 1976 natural disasters in the United States 1976 in Colorado Rivers of Rocky Mountain National Park