(photo courtesy Bureau of Reclamation)
The Wyoming Area Office of the U.S. Department of Interior’s Bureau of Reclamation is lowering the water level in Guernsey Reservoir in preparation for the annual silt run.
Guernsey Dam is located 25 miles below Glendo Dam on the North Platte River in Wyoming. It impounds water for a 6.4 MW hydroelectric powerhouse. Glendo Dam impounds water for a 38 MW powerhouse. Guernsey Reservoir is the furthest downstream reservoir in the system of federal storage reservoirs on the main stem of the North Platte River. During the irrigation season, water released from Guernsey Reservoir serves irrigation development in eastern Wyoming and western Nebraska as well as producing hydropower.
The annual silt run provides silt-laden water to the Goshen, Gering-Fort Laramie and Pathfinder irrigation districts under contract with Reclamation. As the silt-laden water gets diverted into an irrigation canal, the water slows down and the silt sinks to the bottom of the canal. This works as a type of temporary sealant to help minimize seepage out of the bottom and sides of the canal.
On the evening of July 9, the release of water from Glendo Reservoir will be decreased from about 3,500 cubic feet per second (cfs) to between 2,000 cfs and 1,000 cfs. The decreased flow will cause a rapid decline of the Guernsey Reservoir level of about 25 feet starting the morning of July 10 and continuing through July 16. Water being released from Glendo Reservoir will flow through Guernsey Reservoir, flushing silt from Guernsey Reservoir into the canals of downstream irrigators. The silt run will begin on July 16 and is anticipated to continue through July 29.
Beginning on the evening of July 29, the release of water from Glendo Reservoir will be rapidly increased to refill Guernsey Reservoir. The reservoir will rise by about 3 feet per day and is expected to reach the normal reservoir operation level on Aug. 4.
Reclamation is a federal agency under the U.S. Department of the Interior and is the largest wholesale water supplier and second largest producer of hydroelectric power in the country.
