Colorado-Big Thompson project
Encyclopedia
The Colorado-Big Thompson Project is a water diversion project in Colorado
designed to collect West Slope mountain water from the headwaters of the Colorado River
and divert it to Colorado's Front Range
and plains. In Colorado, approximately 80% of the state's precipitation falls on the West Slope, in the Rocky Mountains, while around 80% of the state's growing population lives along the East Slope, between the cities of Fort Collins and Pueblo
.
The project was built, is owned, and is primarily operated by the federal Bureau of Reclamation under the Department of the Interior. By the late 1890s, farmers in northeastern Colorado realized water rights in the area had become over-appropriated. In order to survive the agricultural season, additional water supplies would be needed. Prior to the Dust Bowl
era, agriculture in this section of the state had relied upon sources such as Boulder Creek
, St. Vrain Creek
, Little Thompson River
, Big Thompson River
and the Cache La Poudre River
, all of which are a part of the South Platte River basin and flow into the South Platte River
before the South Platte reaches Greeley, Colorado. In search of a solution, farmers and their representatives approached the Bureau of Reclamation. In the late 1930s a solution was found: divert the water via a 13.2 miles (21.2 km)-long tunnel under the Continental Divide
and Rocky Mountain National Park
. (Tunnel West Portal 40°14′28.16"N 105°48′07.36"W, Tunnel East Portal 40°19′39.85"N 105°34′46.34"W
While the project was originally built for agricultural purposes, it serves multiple demands including municipal and industrial supply, hydro-power generation, recreation, and fish and wildlife. In recent years, however, water supply demands have shifted making municipal and industrial supply the main water beneficiary, rather than irrigation.
Today, the "C-BT" serves over 33 cities and towns in northeastern Colorado, including Fort Collins, Greeley
, Loveland
, Estes Park, Boulder
, and Sterling
, encompassed by 7 counties, providing a secondary source of water for around 830,000 people and an irrigated area of 650,000 acres (2,500 km²). Although water rights allow for up to 310000 acre.ft of water a year to be diverted, annual diversions average around 220000 acre.ft, instead. A drop of over 2000 vertical feet from the Rockies down to the plains allows for power generation. Six power plants on the project produce an average supply of 759 million kilowatt hours of electricity a year. Like the water supply, generated electricity is supplemental. Electricity produced on the C-BT is a source of "peaking power" and is marketed by the Department of Energy
via its Western Area Power Administration
.
The water diversion involved is extensive and the project could not have been constructed without compensation to the West Slope for the water sent East. As a result, the first feature built on the C-BT was Green Mountain Dam and Reservoir, a West Slope facility designed to provide for future water demands in the state's Upper Colorado River Basin. The project was authorized by President Franklin Delano Roosevelt in 1937. Construction began on Green Mountain in the northern part of Summit County
in 1938.
Construction on the project continued through most of the next 20 years. Today, ten reservoirs, and about 18 dams and dikes, the Alva B. Adams Tunnel under the Divide (40°14′28.16"N 105°48′07.36"W to 40°19′39.85"N 105°34′46.34"W), as well as the six power plants, make up the project. Once the water emerges from the Adams Tunnel just southwest of Estes Park, the project is gravity fed, with only one exception: a reversible pump-generator unit that fills Carter Lake. Water falling through penstocks to the Flatiron Power Plant can either be moved to fill Carter, or used to generate electricity before continuing to travel north to Horsetooth Reservoir. Most water beneficiaries on the project receive their C-BT shares from either Horsetooth or Carter Lake reservoirs.
The C-BT is managed by Reclamation's Eastern Colorado Area Office under its Great Plains Region.
40.155191°N 105.855794°W
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
designed to collect West Slope mountain water from the headwaters of the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...
and divert it to Colorado's Front Range
Front Range
The Front Range is a mountain range of the Southern Rocky Mountains of North America located in the north-central portion of the U.S. State of Colorado and southeastern portion of the U.S. State of Wyoming. It is the first mountain range encountered moving west along the 40th parallel north across...
and plains. In Colorado, approximately 80% of the state's precipitation falls on the West Slope, in the Rocky Mountains, while around 80% of the state's growing population lives along the East Slope, between the cities of Fort Collins and Pueblo
Pueblo, Colorado
Pueblo is a Home Rule Municipality that is the county seat and the most populous city of Pueblo County, Colorado, United States. The population was 106,595 in 2010 census, making it the 246th most populous city in the United States....
.
The project was built, is owned, and is primarily operated by the federal Bureau of Reclamation under the Department of the Interior. By the late 1890s, farmers in northeastern Colorado realized water rights in the area had become over-appropriated. In order to survive the agricultural season, additional water supplies would be needed. Prior to the Dust Bowl
Dust Bowl
The Dust Bowl, or the Dirty Thirties, was a period of severe dust storms causing major ecological and agricultural damage to American and Canadian prairie lands from 1930 to 1936...
era, agriculture in this section of the state had relied upon sources such as Boulder Creek
Boulder Creek
Boulder Creek may be:*A community:**Boulder Creek, California*One of several streams:**Boulder Creek in Santa Cruz County**Boulder Creek in San Diego County**Boulder Creek **Boulder Creek...
, St. Vrain Creek
St. Vrain Creek
St. Vrain Creek is a tributary of the South Platte River, approximately long, in north central Colorado in the United States. It drains part of the foothills north of Boulder and the Colorado Piedmont area in the vicinity of Longmont.The creek is formed by the confluence of North and South St....
, Little Thompson River
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 Mountains in Larimer County through the town of Berthoud,...
, Big Thompson River
Big Thompson River
The Big Thompson River is a tributary of the South Platte River, approximately 78 miles long, in the U.S. state of Colorado.- Course of the river :...
and the Cache La Poudre River
Cache La Poudre River
The Cache la Poudre River is in the state of Colorado in the United States.Its headwaters are in the Front Range in Larimer County, in the northern part of Rocky Mountain National Park. The river descends eastward in the mountains through the Roosevelt National Forest in Poudre Canyon...
, all of which are a part of the South Platte River basin and flow into the South Platte River
South Platte River
The South Platte River is one of the two principal tributaries of the Platte River and itself a major river of the American Midwest and the American Southwest/Mountain West, located in the U.S. states of Colorado and Nebraska...
before the South Platte reaches Greeley, Colorado. In search of a solution, farmers and their representatives approached the Bureau of Reclamation. In the late 1930s a solution was found: divert the water via a 13.2 miles (21.2 km)-long tunnel under the Continental Divide
Continental Divide
The Continental Divide of the Americas, or merely the Continental Gulf of Division or Great Divide, is the name given to the principal, and largely mountainous, hydrological divide of the Americas that separates the watersheds that drain into the Pacific Ocean from those river systems that drain...
and Rocky Mountain National Park
Rocky Mountain National Park
Rocky Mountain National Park is a national park located in the north-central region of the U.S. state of Colorado.It features majestic mountain views, a variety of wildlife, varied climates and environments—from wooded forests to mountain tundra—and easy access to back-country trails...
. (Tunnel West Portal 40°14′28.16"N 105°48′07.36"W, Tunnel East Portal 40°19′39.85"N 105°34′46.34"W
While the project was originally built for agricultural purposes, it serves multiple demands including municipal and industrial supply, hydro-power generation, recreation, and fish and wildlife. In recent years, however, water supply demands have shifted making municipal and industrial supply the main water beneficiary, rather than irrigation.
Today, the "C-BT" serves over 33 cities and towns in northeastern Colorado, including Fort Collins, Greeley
Greeley
- Towns :* Greeley, Colorado* Greeley, Iowa* Greeley, Kansas* Greeley Center, Nebraska, commonly shortened to Greeley- People :* Adolphus Greely , American polar explorer* Andrew Greeley , American priest, sociologist, and author...
, Loveland
Loveland, Colorado
Loveland is a Home Rule Municipality that is the second most populous city in Larimer County, Colorado, United States. Loveland is situated north of the Colorado State Capitol in Denver. Loveland is the 14th most populous city in Colorado. The United States Census Bureau that in 2010 the...
, Estes Park, Boulder
Boulder, Colorado
Boulder is the county seat and most populous city of Boulder County and the 11th most populous city in the U.S. state of Colorado. Boulder is located at the base of the foothills of the Rocky Mountains at an elevation of...
, and Sterling
Sterling, Colorado
The City of Sterling is a Home Rule Municipality that is the county seat and the most populous city of Logan County, Colorado, United States. The city population was 14,777 at the 2010 census.-Geography:Sterling is located at...
, encompassed by 7 counties, providing a secondary source of water for around 830,000 people and an irrigated area of 650,000 acres (2,500 km²). Although water rights allow for up to 310000 acre.ft of water a year to be diverted, annual diversions average around 220000 acre.ft, instead. A drop of over 2000 vertical feet from the Rockies down to the plains allows for power generation. Six power plants on the project produce an average supply of 759 million kilowatt hours of electricity a year. Like the water supply, generated electricity is supplemental. Electricity produced on the C-BT is a source of "peaking power" and is marketed by the Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
via its Western Area Power Administration
Western Area Power Administration
The Western Area Power Administration markets and delivers hydroelectric power and related services within a 15-state region of the central and western U.S. It is one of four power marketing administrations within the U.S...
.
The water diversion involved is extensive and the project could not have been constructed without compensation to the West Slope for the water sent East. As a result, the first feature built on the C-BT was Green Mountain Dam and Reservoir, a West Slope facility designed to provide for future water demands in the state's Upper Colorado River Basin. The project was authorized by President Franklin Delano Roosevelt in 1937. Construction began on Green Mountain in the northern part of Summit County
Summit County, Colorado
Summit County is the 19th most populous of the 64 counties of the state of Colorado of the United States. The county population was 23,538 at U.S. Census 2000. The county seat is Breckenridge...
in 1938.
Construction on the project continued through most of the next 20 years. Today, ten reservoirs, and about 18 dams and dikes, the Alva B. Adams Tunnel under the Divide (40°14′28.16"N 105°48′07.36"W to 40°19′39.85"N 105°34′46.34"W), as well as the six power plants, make up the project. Once the water emerges from the Adams Tunnel just southwest of Estes Park, the project is gravity fed, with only one exception: a reversible pump-generator unit that fills Carter Lake. Water falling through penstocks to the Flatiron Power Plant can either be moved to fill Carter, or used to generate electricity before continuing to travel north to Horsetooth Reservoir. Most water beneficiaries on the project receive their C-BT shares from either Horsetooth or Carter Lake reservoirs.
The C-BT is managed by Reclamation's Eastern Colorado Area Office under its Great Plains Region.
External links
- The Colorado-Big Thompson Project
- The Great Plains Region
- The Eastern Colorado Area Office
- Horsetooth and Carter Lake reservoirs
- "Man-made River Pierces The Rockies" , September 1947, Popular Science
40.155191°N 105.855794°W