Encyclopedia of the Great Plains

TRANSMOUNTAIN WATER DIVISION

When settlers arrived in the Great Plains they noticed that more water was available in the mountains than on the adjacent flatlands, and they developed transmountain water diversion projects, as well as other schemes, to capture mountain runoff in storage reservoirs for use during dry periods. Today, much of the water supply of the Great Plains region near the mountains is based on stored mountain water. Without this imported water, the region could not support as many farms and cities as it does.

A good example of transmountain water diversions is the Colorado–Big Thompson Project. In this project, water flows thirteen miles through a tunnel under Rocky Mountain National Park from the Colorado River headwaters to the East Slope. The project diverts 230,000 acre-feet to serve some 2,428 farms and communities on the East Slope. It involves extensive facilities that include twelve reservoirs, thirty-four miles of tunnel, ninety-five miles of canals or conduits, six hydroelectric plants, and three pumping stations. The project was long in the making and embroiled in political controversy. The preliminary survey was made in 1884; northern Colorado had organized for the "Grand Lake Project" by 1933; and it was completed in 1956. Water management remains a controversial issue in the region, and it is doubtful that more large transmountain water diversion projects will be built.

Neil S. Grigg Colorado State University

Tyler, Daniel. The Last Water Hole in the West: The Colorado-Big Thompson Project and the Northern Colorado Water Conservancy District. Niwot: University Press of Colorado, 1992.