Shoshone Project
The Shoshone Project includes about 93,450 irrigable acres. The key features of the Project are the buffalo Bill Dam and Reservoir. Diversion dams, canals, laterals, drains and numerous concrete structures complete the irrigation system for the project.
The Buffalo Bill Dam was completed in 1910. It is a constant radius concrete dam, 108 feet thick at the base and 0 feet thick at the crest. The original structural height of the dam was 325 feet, once the highest in the world.
Modifications to Buffalo Bill Dam were authorized by congress in 1982. These include raising the crest of the dam 25 feet. The original unlined, uncontrolled weir spillway will be replaced with a larger gated and lined spillway. Construction of the modifications is schedule for completion in 1991.
The active storage capacity of the enlarged reservoir is 623,557 acre feet at elevation 5393.5. The enlarged reservoir has a surface area of 8,315 acres and a length of about 9 miles.
The irrigation system for the Shoshone Project includes two diversion dams, about 140 miles of tunnels and canals, about 564 miles of distribution laterals and about 673 miles of drains. The canals and laterals include numerous concrete control structures including check and drop structures, chutes and siphons. Portions of the canals and laterals are lined with concrete or PVC membrane. Some laterals are buried in pipe. However, most of the canal and lateral system consists of unlined open channels. All lands on the Shoshone Project are severed by gravity flow except about 2,000 acres in the Heart Mountain Division.
Irrigation water for the Project is diverted at the Buffalo Bill Dam and at two diversion dams. Stored irrigation water is released from Buffalo Bill Dam into the Shoshone River through outlet gates at the dam and through three power plants downstream of the dam. This water is diverted further downstream by three of the four divisions of the Project. Irrigation water is provided to the fourth division directly from the Buffalo Bill Dam through the conduit that also serves two of the power plants.
The diversion for the Garland and Frannie division is the Corbett Diversion Dam. The dam is located on the Shoshone River about sixteen miles downstream of Buffalo Bill Dam. The diversion dam is a concrete overflow weir structure with a height of 12 feet and a length of 400 feet. The dam diverts water into the Corbett Tunnel of the Garland Canal.
The Willwood Division diverts water at the Willwood Diversion Dam. This dam is also located on the Shoshone River about 22 miles downstream of Buffalo Bill Dam. The diversion dam is a concrete gravity structure with a height of 41 feet, a weir crest length of 271 feet and an overall crest length of 476 feet. The dam diverts water from the Shoshone River into the Willwood Canal.
The Heart Mountain Division receives water directly from the Buffalo Bill Reservoir via the Shoshone Canyon conduit. The conduit provides water for two power plants as well as the Heart Mountain Canal. About a mile below the dam 43% of the water flow in the conduit is diverted for the Buffalo bill Power Plant. The remainder of the water travels another 2 miles to the outlet of the conduit. At this point the water is split between the Heart Mountain Power Plant and the Shoshone River Siphon on the Heart Mountain Canal.
After diversion from the river or the reservoir, the irrigation water is distributed to the Project through a series of canals and laterals. The two oldest divisions of the Shoshone Project share main carriage facilities. The other two divisions have separate carriage facilities.
The Garland Division comprises about 35,800 irrigable acres north of the Shoshone River near Powell, Wyoming. These lands are served by the Garland Canal and the Frannie Canal. Water for the irrigation distribution system flows from the river diversion through the 3-mile long Corbett Tunnel into the Garland Canal. The Garland Canal has an initial flow capacity of 1,000 cubic feet per second and a length of about 18 miles. The Frannie Canal takes off from the Garland Canal about eleven miles downstream of the Corbett Tunnel. The Frannie Canal has an initial capacity of 550 cubic feet per second and a total length of about 44 miles. However, only the first 14 miles of the Frannie Canal serve the Garland Division. The remaining 30 miles serve the Frannie Division. The Garland Division is further served by about 145 miles of distribution laterals and 350 miles of open and closed drains. Ralston Reservoir is located about seven miles downstream of the Corbett Tunnel. This limited capacity reservoir provides some operation control of the Garland Canal as well as providing an emergency waste route during storms and collecting drainage water.
The Frannie Division comprises about 15,120 irrigable acres north of the Shoshone River near the Wyoming-Montana border. Nearby towns are Frannie and Deaver, Wyoming. Water for the Frannie division is supplies by the Frannie Canal and the Deaver Canal. The Frannie Canal begins in the Garland Division and extends about 30 miles through the Frannie Division. The Deaver Canal takes off from the Frannie Canal at the Garland-Frannie Division Boundary. The Deaver Canal has an initial capacity of 194 cubic feet per second and a length of about 24 miles. The Frannie Division also contains about 121 miles of distribution laterals and 104 miles of open and closed drains. The Deaver reservoir is located on the Frannie Canal. This reservoir provides off stream storage with a capacity of about 680 acre feet.
The Willwood Division comprises about 11,410 irrigable acres south of the Shoshone River between the towns of Ralston and Garland, Wyoming. Farms on the Willwood division are served by the Willwood Canal, which parallels the Shoshone River. Water is diverted directly from the river into the Willwood Canal. The Willwood Canal has an initial capacity of 320 cubic feet per second and a length of about 17 ½ miles. The Willwood Division is also served by about 53 miles of distribution laterals and 73 miles of open and closed drains.
The Heart Mountain Division comprises about 31,120 irrigable acres north of the Shoshone River from Cody, Wyoming to about 7 miles north of Ralston, Wyoming. Water for the Heart Mountain Division is provided by the Heart Mountain Canal. The canal begins at the inlet to the Shoshone River Siphon, which spans the river below the Shoshone Canyon Conduit outlet. The canal has an initial capacity of 914 cubic feet per second and a length of about 28 miles. The Heart Mountain Division is also served by about 140 miles of distribution laterals and 145 miles of open and closed drains.
