Upper Stillwater Reservoir is a large high mountain reservoir on the south slope of the High Uintas in

Duchesne County, Utah Duchesne County ( ) is a county in the northeast part of the U.S. state of Utah. As of the 2010 United States Census, the population was 18,607. Its county seat is Duchesne, and the largest city is Roosevelt. History Much of Duchesne County wa ...

. The reservoir is part of the Central Utah Project. The reservoir was created in 1987 by the construction of a concrete gravity dam (Upper Stillwater Dam). The architecture of the rolled concrete dam is an attraction for engineers. The reservoir elevation is 8,176 ft, and the mean depth is 103.5 ft. Available fish species include rainbow, brown, and brook trout. The watershed is primarily the

Uinta Mountains The Uinta Mountains ( ) are an east-west trending chain of mountains in northeastern Utah extending slightly into southern Wyoming in the United States. As a subrange of the Rocky Mountains, they are unusual for being the highest range in the c ...

, the watershed high point being Ostler Peak (12,717 ft). It is estimated that twice or more the reservoir capacity is diverted towards the

Wasatch Front The Wasatch Front is a metropolitan region in the north-central part of the U.S. state of Utah. It consists of a chain of contiguous cities and towns stretched along the Wasatch Range from approximately Provo in the south to Logan in the nort ...

annually. The primary use of the water is for irrigation.

Recreation

The area has one main campground, Rock Creek. The reservoir serves as a popular trailhead into the

High Uintas Wilderness The High Uintas Wilderness is a wilderness area located in northeastern Utah, United States. The wilderness covers the Uinta Mountains, encompassing parts of Duchesne and Summit counties. Designated as a wilderness in 1984, the area is located wi ...

Area, with the boundary only one mile north of the dam near the high water line for the reservoir. Recreation management is under the jurisdiction of the U.S. Forest Service,

Ashley National Forest Ashley National Forest is a National Forest located in northeastern Utah and southwestern Wyoming. Within the Forest's bounds are (with in Utah and in Wyoming) of vast forests, lakes, and mountains, with elevations ranging from . The fores ...

. The managed recreation season is from June through September, with high use on holidays and weekends. Boating, swimming, camping, fishing, hiking, horseback riding, picnicking, recreational vehicle driving, wildlife viewing, and winter sports are popular activities.

Annual Spill

The Stillwater Dam is designed with a steep

stepped spillway A stepped spillway is a spillway with steps on the spillway chute to assist in the dissipation of the kinetic energy of the descending water. This eliminates or reduces the need for an additional energy dissipator, such as a body of water, at the ...

. During years of high snow or fast melt conditions, the dam may fill until the water elevation reaches the spillway. The spill creates a curtain of falling water 600 feet wide and 200 feet tall. The event typically lasts for a few days and commonly attracts tourist and media attention. Stillwater spilling

References

External links

Consultant's project page for Upper Stillwater Dam, including gallery
* http://www.waterquality.utah.gov/watersheds/lakes/UPPERSTL.pdf * http://www.recreation.gov/recAreaDetails.do?contractCode=NRSO&recAreaId=971&agencyCode=131 {{authority control Buildings and structures in Duchesne County, Utah Lakes of Duchesne County, Utah Reservoirs in Utah Protected areas of Duchesne County, Utah 1987 establishments in Utah