Power Generation

The Colorado-Big Thompson Project's six original power plants generate an average of 770 million kilowatt-hours of renewable energy per year. The C-BT Project’s West Slope pump plants at Farr and Willow Creek annually use 70 million kilowatt-hours. The remaining 700 million-kilowatt hours are sold to customers in Colorado, Eastern Wyoming, Kansas and Western Nebraska.

Power is generated by water flowing through C-BT Project power plant turbines to produce hydroelectricity. The power sold to customers is enough to supply approximately 68,000 homes for a year.
Five of the C-BT Project's power plants are located on the East Slope between Rocky Mountain National Park and the mouth of the Big Thompson Canyon. The Green Mountain Power Plant is located on the Blue River near Kremmling on the West Slope.

The Bureau of Reclamation owns and operates all six of the C-BT Project's hydropower plants, and the Western Area Power Administration markets and distributes the power.

Power for the Pump Plant at Lake Granby
When the C-BT Project was planned in the 1930s, the power plants at Lake Estes and Green Mountain Reservoir were designed to provide power to the Farr (previously Granby) and Willow Creek pump plants. This was largely due to insufficient electrical infrastructure and power production on the West Slope when the project was built.

Electricity from the Lake Estes Power Plant reaches the Farr and Willow Creek plants via a 69,000-volt transmission line extending through the Adams Tunnel beneath Rocky Mountain National Park. Today, even with adequate West Slope electrical infrastructure and power projection, the Adams Tunnel transmission line still provides the West Slope pump plants with a portion of their electrical needs.

Water Descends 2,600 Vertical Feet
Water flows beneath Rocky Mountain National Park via the Adams Tunnel to the East Slope and descends the Front Range mountains nearly 2,600 vertical feet through these five power plants and four reservoirs:

  • Mary's Lake Power Plant and Mary's Lake
  • Estes Power Plant and Lake Estes
  • Pole Hill Power Plant and Pinewood Reservoir
  • Flatiron Power Plant and Flatiron Reservoir
  • Big Thompson Power Plant

Plants Respond to Peak Power Needs
The C-BT Project's East Slope power plants supply power for peak electrical demands by using a system of forebays, afterbays and penstocks.  

When peak electrical power is needed, water is moved from a plant's forebay (a small reservoir above a hydroelectric power plant) into a penstock leading to the power plant.

The force of the water moving through the penstock and turbine generates electricity. After passing through the turbine, the water is typically released into an afterbay (a small reservoir located below a hydroelectric power plant).

C-BT Power Plant Profile Map
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Green Mountain Power Plant
The Green Mountain Power Plant is located on the West Slope at the base of Green Mountain Dam on the Blue River southeast of Kremmling. The plant was the first power unit of the C-BT Project to produce electricity. It began power production in May 1943.

Northern Water Hydropower Plants
Northern Water's first hydropower project, the Robert V. Trout Hydropower Plant, is located at Carter Lake on the East Slope. The Trout Hydropower Plant is the first power structure built, owned and operated by Northern Water.

The Trout Hydropower Plant began generating electricity in May 2012. It is capable of producing 7 to 10 million kilowatt-hours of electricity per year. The Poudre Valley Rural Electrical Association markets and distributes the power from the plant.

Northern Water's second hydropower project, the Granby Hydropower Plant, is located at the base of Lake Granby Dam on the West Slope in Grand County. It is also owned and operated by Northern Water.

The Granby Hydropower Plant began operating in May 2016, and is capable of producing 5 million kilowatt-hours of electricity per year. Mountain Parks Electric markets and distributes the plant's power.