Colorado–Big Thompson Project

Grand Lake, Colorado

The Colorado–Big Thompson Project (C-BT) is a large-scale water diversion project in the state of Colorado, United States. The project was initiated to address the water needs of the arid regions on the eastern slope of the Rocky Mountains by diverting water from the Colorado River basin on the western slope to the eastern slope.

History

The Colorado–Big Thompson Project was authorized by the United States Congress in 1937 and construction began in 1938. The project was completed in 1957. It was designed and constructed by the Bureau of Reclamation, a federal agency under the United States Department of the Interior.

Components

The C-BT Project consists of a complex system of reservoirs, tunnels, pipelines, and power plants. Key components include:

• Lake Granby: The primary storage reservoir on the western slope.
• Adams Tunnel: A 13.1-mile tunnel that conveys water from the western slope to the eastern slope.
• Horsetooth Reservoir: A major storage reservoir on the eastern slope.
• Carter Lake: Another significant storage reservoir on the eastern slope.
• Green Mountain Reservoir: Provides water storage and regulation on the western slope.
• Flatiron Reservoir: Part of the distribution system on the eastern slope.
• Big Thompson River: The river into which the diverted water is released on the eastern slope.

Purpose

The primary purpose of the Colorado–Big Thompson Project is to provide a reliable water supply for agricultural, municipal, and industrial uses on the eastern slope of Colorado. The project also generates hydroelectric power and provides recreational opportunities.

Hydroelectric Power

The C-BT Project includes several hydroelectric power plants, which generate electricity as water is transported through the system. These power plants include:

• Granby Pumping Plant
• Marys Lake Powerplant
• Estes Powerplant
• Flatiron Powerplant
• Big Thompson Powerplant

Environmental Impact

The diversion of water from the Colorado River basin has had significant environmental impacts, including changes to river flow patterns and effects on aquatic ecosystems. Efforts have been made to mitigate these impacts through various environmental programs and initiatives.

Recreation

The reservoirs and surrounding areas of the C-BT Project provide numerous recreational opportunities, including boating, fishing, camping, and hiking. Popular recreational sites include Horsetooth Reservoir and Carter Lake.

Management

The Colorado–Big Thompson Project is managed by the Northern Colorado Water Conservancy District in cooperation with the Bureau of Reclamation. The project serves over 30 cities and towns and provides water to more than 600,000 people.

See Also

• Bureau of Reclamation
• Colorado River
• Northern Colorado Water Conservancy District
• Rocky Mountains
• Water management in Colorado