This article needs additional citations for verification . (June 2014) (Learn how and when to remove this template message)
The Colorado-Big Thompson Project (abbreviated C-BT) is a federal 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.
Eleven reservoirs, about 18 dams and dikes, the Alva B. Adams Tunnel under the Continental Divide, as well as six power plants, make up the project. The C-BT is owned and primarily managed by the U.S. Bureau of Reclamation's Eastern Colorado Area Office under its Great Plains Region.
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-mile (21.2 km)-long tunnel under the Continental Divide and Rocky Mountain National Park. (Tunnel West Portal , Tunnel East Portal )
The proposed water diversion was 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.
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 1 million people and an irrigated area of 640,000 acres (2,500 km²). Although water rights allow for up to 310,000 acre feet (380,000,000 m3) of water a year to be diverted, annual diversions average around 220,000 acre feet (270,000,000 m3), instead. A drop of over 2000 vertical feet from the Rockies down to the plains allows for power generation. Seven 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.
An extensive series of reservoirs, pumps and conduits on the west side of the Rockies serve to collect water from the headwaters of the Colorado River, as well as two tributaries, Cottonwood Creek and the Fraser River. Lake Granby, located in eastern Grand County, is the primary C-BT storage facility, with a capacity of 539,800 acre feet (0.6658 km3). The reservoir is held by the 298-foot (91 m) high Granby Dam and 12,722 feet (3,878 m) of auxiliary dikes.
Willow Creek Reservoir is built on Willow Creek, which is located west of Lake Granby, and provides a source from which water is diverted and pumped to Granby. Windy Gap Reservoir is a small diversion facility located directly below the confluence of the Colorado and Fraser rivers, about 5 miles (8.0 km) downstream of Granby. Water from the Fraser River, as well as other inflows to the Colorado below Granby Dam, is diverted here and pumped eastwards to Lake Granby. The Windy Gap project is not owned by the Bureau of Reclamation, but by the Municipal Subdistrict, a consortium of 14 Front Range cities, water providers and an electric utility. However, Windy Gap water uses the storage and distribution facilities of the Bureau of Reclamation's C-BT.
From Lake Granby the water is lifted 125 feet (38 m) up to Shadow Mountain Lake, which is located on the Colorado River west of the natural Grand Lake. The two bodies of water are connected by a short channel which allows water to flow freely to the intake of the Alva B. Adams Tunnel on Grand Lake's eastern shore. The water then flows 13.2 miles (21.2 km) under the Continental Divide through the Adams Tunnel, which can carry up to 550 cubic feet per second (16 m3/s) to the Eastern Slope.
Once the water emerges from the Adams Tunnel just southwest of Estes Park, the system is almost entirely gravity powered, dropping some 2,800 feet (850 m) as it descends to the foothills of the Rocky Mountains west of Loveland. The tunnel outlet is located at East Portal Reservoir, a small regulating pool on the Wind River. From here it is transported via an inverted siphon across the Aspen Creek valley and drops 205 feet (62 m) to Mary’s Lake, where it drives the 8.1 megawatt (MW) Mary’s Lake Powerplant. Mary’s Lake is a small natural lake enlarged to form a second regulatory reservoir. The water then drops 515 feet (157 m) to the 45-MW Estes Powerplant at Lake Estes, which is formed by Olympus Dam on the Big Thompson River at Estes Park. Lake Estes serves to regulate both C-BT water and the natural flows of the Big Thompson River.
From Lake Estes the water travels east via the Olympus and Pole Hill Tunnels to the 38.2 MW Pole Hill Powerplant, where it drops 825 feet (251 m), and flows via the shorter Rattlesnake Tunnel to Pinewood Lake. The water then enters the Bald Mountain Tunnel, heading east to a final drop of 1,055 feet (322 m) at 94.5 MW Flatiron Powerplant. From the tailrace of the powerplant the water enters Flatiron Reservoir from which the water is distributed to the East Slope.
Once the water reaches Flatiron Reservoir, it splits into two branches which distribute water to about 50 miles (80 km) of the Front Range Corridor, from Fort Collins to near Denver. The northern branch consists of the Horsetooth Feeder Canal and tunnels which feeds water by gravity to Horsetooth Reservoir. The reservoir is formed by four dams in the hills west of Fort Collins and has a total capacity of 151,750 acre feet (0.18718 km3). The northern end of the reservoir outlets into the Charles Hansen Supply Canal, which mainly supplies agriculture in the Cache la Poudre River valley. There is a smaller outlet at Soldier Canyon which provides water to the Fort Collins area.
Water flowing into the southern branch must be pumped into Carter Lake Reservoir, located west of Berthoud. The reservoir can hold up to 112,230 acre feet (0.13843 km3) of water. During times of peak power demand, water can be released back from Carter into Flatiron via a pump-generating unit. Water flows south from Carter Lake into the St. Vrain Supply Canal, which provides water to the Little Thompson River and Saint Vrain Creek. From the end of the St. Vrain Canal the Boulder Creek Supply Canal extends southward to Boulder Creek, and the South Platte Supply Canal extends northeast from there to the South Platte River.
Glen Canyon Dam is a concrete arch-gravity dam on the Colorado River in northern Arizona, United States, near the town of Page. The 710-foot (220 m) high dam was built by the U.S. Bureau of Reclamation (USBR) from 1956 to 1966 and forms Lake Powell, one of the largest man-made reservoirs in the U.S. with a capacity of 27 million acre feet (33 km3). The dam is named for Glen Canyon, a series of deep sandstone gorges now flooded by the reservoir; Lake Powell is named for John Wesley Powell, who in 1869 led the first expedition to traverse the Colorado's Grand Canyon by boat.
The Big Thompson River is a tributary of the South Platte River, approximately 78 miles (123 km) long, in the U.S. state of Colorado.
Middle Park is a high basin in the Rocky Mountains of north-central Colorado in the United States. It is located in Grand County, on the southwest slope of Rocky Mountain National Park, approximately 50 miles (80 km) west of Boulder.
Grand Lake is Colorado's largest and deepest natural lake. It is located in the headwaters of the Colorado River in Grand County, Colorado. On its north shore is located the historic and eponymous town of Grand Lake. The lake was formed during the Pinedale glaciation, which occurred from 30000 BP to 10000 BP. The glacial terminal moraine created a natural dam. Natural tributaries to the lake are the North Inlet and East Inlet, both of which flow out of Rocky Mountain National Park, which surrounds the lake on three sides. Grand Lake is located 1 mile from the Park's western entrance. Grand Lake was named Spirit Lake by the Ute Tribe because they believed the lake's cold waters to be the dwelling place of departed souls.
Horsetooth Reservoir is a large reservoir in southern Larimer County, Colorado, just west of the city of Fort Collins, Colorado. The reservoir sits in the foothills above the town on the western side of the Dakota Hogback, which contains the reservoir along its eastern side. The reservoir runs north-south for approximately 6.5 miles (10 km) and is approximately one-half mile (1 km) wide. It was constructed in 1949 by the Bureau of Reclamation as part of its federal Colorado-Big Thompson Project or "C-BT". Water distribution is currently managed by Reclamation and operated by the Northern Colorado Water Conservancy District. Horsetooth and Carter Lake serve as the two principal reservoirs for water diverted eastward under the continental divide via the C-BT.
Trinity Dam is an earthfill dam on the Trinity River located about 7 miles (11 km) northeast of Weaverville, California in the United States. The dam was completed in the early 1960s as part of the federal Central Valley Project to provide irrigation water to the arid San Joaquin Valley.
Flaming Gorge Dam is a concrete thin-arch dam on the Green River, a major tributary of the Colorado River, in northern Utah in the United States. Flaming Gorge Dam forms the Flaming Gorge Reservoir, which extends 91 miles (146 km) into southern Wyoming, submerging four distinct gorges of the Green River. The dam is a major component of the Colorado River Storage Project, which stores and distributes upper Colorado River Basin water.
Granby Dam is an earthfill dam that dams the Colorado River 5.5 miles (8.9 km) northeast of Granby, Colorado in Grand County, Colorado. This 298-foot (91 m)-tall dam was constructed between 1941 and 1950 and has a drainage area of 311 square miles (810 km2). The Granby Dam's reservoir is known as Lake Granby, the largest reservoir component of the Colorado-Big Thompson Project. Lake Granby stores Colorado River water that is diverted under the Continental Divide for agriculture and municipal use within north-eastern Colorado including the cities of Boulder, Fort Collins, Loveland, and Greeley. In addition to the waters of the Colorado, water from Willow Creek just below the dam is pumped up 175 feet (53 m) to Lake Granby. Water from Lake Granby is pumped 125 feet (38 m) higher by the Granby Pumping Plant to the Granby Pump Canal, which extents 1.8 miles (2.9 km) to Shadow Mountain Lake, from which water is diverted through the Alva B. Adams Tunnel to the East Slope.
The Fryingpan-Arkansas Project, or "Fry-Ark," is a water diversion, storage and delivery project serving southeastern Colorado. The multi-purpose project was authorized in 1962 by President Kennedy to serve municipal, industrial, and hydroelectric power generation, and to enhance recreation, fish and wildlife interests. Construction began in 1964 and was completed in 1981. The project includes five dams and reservoirs, one federal hydroelectric power plant, and 22 tunnels and conduits totaling 87 miles (140 km) in length. The Bureau of Reclamation, under the Department of the Interior built and manages the project.
The Central Utah Project is a US federal water project that was authorized for construction under the Colorado River Storage Project Act of April 11, 1956, as a participating project. In general, the Central Utah Project develops a portion of Utah's share of the yield of the Colorado River, as set out in the Colorado River Compact of 1922.
Whiskeytown Dam is an earthfill dam on Clear Creek, a tributary of the Sacramento River of northern California in the United States.
Seminoe Dam is a concrete thick-arch dam on the North Platte River in the U.S. state of Wyoming. The dam stores water for irrigation and hydroelectricity generation, and is owned and operated by the U.S. Bureau of Reclamation. It is the uppermost dam on the North Platte River and is located directly upstream from the Kortes Dam. It lies in a narrow, isolated canyon formed by the North Platte cutting through the Seminoe Mountains about 40 miles (64 km) northeast of Rawlins. The 295-foot (90 m) dam forms Seminoe Reservoir, which covers more than 20,000 acres (8,100 ha) when full. Seminoe State Park is adjacent to the reservoir. The small village of Seminoe Dam abuts the dam and reservoir, and provides residence for the dam attendants and park services personnel.
Green Mountain Reservoir lies at the northern end of Summit County, Colorado along the Blue River. The Green Mountain Dam was built between 1938 and 1942 by the United States Bureau of Reclamation. The reservoir and its dam store water to benefit Colorado's Western Slope. Created by President Roosevelt as part of the Colorado-Big Thompson Project in 1937, Green Mountain was the first facility to be constructed. This is because it represents a great compromise that made the C-BT project possible: it compensates the Western Slope for water diverted to cities in Northern Colorado from Lake Granby further upstream on the Colorado River. Water from Green Mountain Dam is released either over the spillway, through the dam, or through the hydroelectric powerplant at the dam's base. The Green Mountain Power Plant has the capacity to generate up to 21,000 kilowatts, using two generators. Combined with the other five Federal power plants on the C-BT, enough electricity is produced annually to power almost 60,000 American homes.
The Alva B. Adams Tunnel is the principal component of the largest transmountain water project in Colorado, the Colorado-Big Thompson Project (C-BT). The tunnel transfers water from the western slope of the Colorado River drainage to the eastern Front Range of Colorado. It is 13.1 miles (21.1 km) long, with a concrete lined diameter of 9.75 feet (2.97 m). The tunnel drops 109 feet (33 m) in elevation along its length and runs in a straight line under the Continental Divide from west to east, passing under Rocky Mountain National Park. At its deepest point, the tunnel is about 3,800 feet (1,200 m) below the surface of the mountain peaks. Construction began on 15 June 1940, but was suspended as a result of World War II priorities, from the end of 1942 to August 1943. The tunnel was holed through on 31 March 1944, an event that was broadcast throughout the United States by NBC Radio. The tunnel was posthumously named for its chief advocate, US Senator Alva B. Adams.
The San Juan–Chama Project is a U.S. Bureau of Reclamation interbasin water transfer project located in the states of New Mexico and Colorado in the United States. The project consists of a series of tunnels and diversions that take water from the drainage basin of the San Juan River – a tributary of the Colorado River – to supplement water resources in the Rio Grande watershed. The project furnishes water for irrigation and municipal water supply to cities along the Rio Grande including Albuquerque and Santa Fe.
Gibson Dam is a concrete arch dam on the Sun River, a tributary of the Missouri River, about 60 miles (97 km) west of Great Falls, Montana in the United States. Located on the eastern edge of the Rocky Mountains, the dam was built by the U.S. Bureau of Reclamation (USBR) between 1926 and 1929 as part of the Sun River Project to develop about 93,000 acres (38,000 ha) of irrigated land in the Sun River Valley.
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 from the Colorado Western Slope over the Continental Divide for agricultural, industrial, and municipal water supply in northeastern Colorado. The District's offices are in Berthoud, Colorado.