Fontenelle Dam
| Fontenelle Dam | |
|---|---|
 |
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| Location | Lincoln and Sweetwater counties, Wyoming, USA |
| Coordinates | 42°01′42.4″N 110°03′37.9″W / 42.028444°N 110.060528°WCoordinates: 42°01′42.4″N 110°03′37.9″W / 42.028444°N 110.060528°W |
| Construction began | 1961 |
| Opening date | 1964 |
| Operator(s) | U.S. Bureau of Reclamation |
| Dam and spillways | |
| Type of dam | Zoned earthfill |
| Impounds | Green River |
| Height | 139 feet (42 m) |
| Length | 5,421 feet (1,652 m) |
| Dam volume | 5,265,000 cu yd (4,025,000 m3) |
| Spillway type | Gated spillway |
| Spillway capacity | 20,200 cu ft/s (570 m3/s) |
| Reservoir | |
| Creates | Fontenelle Reservoir |
| Total capacity | 345,360 acre feet (0.42600 km3) |
| Catchment area | 4,156 sq mi (10,760 km2) |
| Power station | |
| Hydraulic head | 121 ft (37 m) |
| Turbines | 1 x 10 MW Francis-type |
| Installed capacity | 10 MW |
Fontenelle Dam was built between 1961 and 1964 on the Green River in southwestern Wyoming. The 139-foot (42 m) high zoned earthfill dam impounds the 345,360-acre-foot (0.42600 km3) Fontenelle Reservoir. The dam and reservoir are the central features of the Seedskadee Project of the U.S. Bureau of Reclamation, which manages the Fontenelle impoundment primarily as a storage reservoir for the Colorado River Storage Project. The dam suffered a significant failure in 1965, when the dam's right abutment developed a leak. Emergency releases from the dam flooded downstream properties, but repairs to the dam were successful. However, in 1983 the dam was rated "poor" under Safety Evaluation of Existing Dams (SEED) criteria, due to continuing seepage, leading to an emergency drawdown. A concrete diaphragm wall was built through the core of the dam to stop leakage.
Initially conceived as a storage reservoir for irrigation water, the project was suspended for a time in 1962 to pursue a study of high-altitude irrigation methods. The results of the studies caused the cancellation of many irrigation features for the project. The primary project rationale evolved to support Wyoming water rights in the Colorado River basin, retaining water that would otherwise go downstream to states in the lower Colorado basin. The dam provides power generation as a secondary feature. One motivation for the deferral of irrigation activities was the discovery of trona in the southern portion of the proposed irrigated region. As the extraction of trona was a higher-value activity, the removal of those lands from the project made the irrigation project nonviable.
Development of the upper Green River basin was included in a 1946 Bureau of Reclamation report on the Colorado River basin. A 1950 supplementary report dealt with details of the proposed Seedskadee Project, followed by another addendum in 1953. The Colorado River Storage Project, including the Seedskadee Project, was authorized by Congress in 1956. Initial planning was completed in 1959, and amended in 1961 to increase the capacity of Fontenelle Reservoir to 345,400 acre feet (0.4260 km3), making the construction of a powerplant feasible. Work was stopped on irrigation infrastructure in 1962. The dam featured unusually large outlet works, capable of discharging 18,000 cu ft/s (510 m3/s) (compared with a spillway capacity of 20,200 cu ft/s (570 m3/s)) because the outlet works could be increased in size at lower cost than the spillway.
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