Where Does Cheyenne's Water Come From?
Approximately 70 percent of the water used in Cheyenne comes from mountain streams in the Medicine Bow and Laramie Mountain Ranges. The majority of this water comes from a trans-basin trade system, known as Stage I/II. It is a three part system that moves water from one side of a mountain to another, trades water across a valley, and then pipes water across two mountain ranges to Cheyenne.
How the Stage I/II System Works
- In the first part of the system, the Board of Public Utilities collects water from streams west of the Continental Divide and transports the water to the east side of the Continental Divide by a tunnel. Two reservoirs, Hog Park and Seminoe Reservoirs, store the water until needed for trade purposes.
- The second part of the system trades water from Hog Park Reservoir and from Seminoe Reservoir for water in Rob Roy Reservoir. The trade exchanges water from the west side of the North Platte River Watershed for water on the east side.
- The third part of the system transports water from Rob Roy Reservoir to Granite Springs and Crystal Reservoirs. The water is piped by gravity down the Medicine Bow Mountains, across the Laramie River Valley and over the Laramie Mountains. Once over the top of Laramie Mountains, the water flows by gravity to Granite and Crystal Reservoirs.
It's a vast, complex system that relies on the cooperation and assistance of many organizations, such as the U.S. Forest Service, U.S. Bureau of Reclamation and the Wyoming State Engineer. The system also relies heavily on mountain snow.
The Importance of Snow
It takes snow in the Sierra Madre Mountains, Medicine Bow Mountains and the Laramie Mountains to supply Cheyenne with water. For this reason, Cheyenne tracks how much snow is in these mountains throughout the winter using SNOTEL sites.
Snow telemetry sites, or SNOTEL, are specialized, automated weather stations that track snow-pack, the amount of moisture in the snow, temperatures, wind and other weather conditions. The Board of Public Utilities uses the information from these sites to estimate how much water Cheyenne will be able to collect in its reservoirs.
The Board of Public Utilities funded three SNOTEL sites, one in each of the drainages important to Cheyenne's water system.
The remaining 30 percent of water used in Cheyenne comes from wells. Cheyenne has four well fields to the west and northwest of the City. These well fields contain 35 wells that deliver water to Cheyenne.