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 eastern 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. History 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 -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. Benefits While the project was originally built for agricultural purposes, it serves multiple demands including municipal and industrial supply, hydro-power