Buffalo Bill Dam
Buffalo Bill Dam is a concrete arch-gravity dam on the Shoshone River in the U.S. state of Wyoming. Originally, it was the tallest dam in the world when it opened in 1910; a extension was added in 1992 in one of the numerous changes and improvements to the structure and its support facilities, which include two full-time power generators and two seasonal operations added between 1920 and 1994, and a irrigation tunnel completed in 1939.
The dam is located in Shoshone Canyon, and named after the famous Wild West figure William "Buffalo Bill" Cody, who founded the nearby town of Cody and owned much of the land now covered by the reservoir formed by its construction. It is part of the Shoshone Project, successor to several visionary schemes promoted by Cody to irrigate the Bighorn Basin and turn it from a semi-arid sagebrush-covered plain to productive agricultural land. Known at the time of its construction as Shoshone Dam, it was renamed in 1946 to honor Cody.
The original structure was designed by engineer Daniel Webster Cole and was built between 1905 and 1910. It was listed on the National Register of Historic Places in 1971 and named a National Historic Civil Engineering Landmark by the American Society of Civil Engineers in 1973. The land around the reservoir is maintained as Buffalo Bill State Park.
Description
The dam is a concrete arch-gravity dam, wide at the base and wide at the crest, with an original height of, extended between 1985 and 1992. The concrete structure measures deep at the base, tapering to at the crest, with a volume of of concrete. It is anchored into Precambrian granitic rock on either side. The spillway is an uncontrolled overflow weir on the south side, wide, dropping through a tunnel in the south abutment.The first of four full-time and seasonal power generation facilities was added in 1922.
- Originally equipped with two generators, the Shoshone Power Plant was expanded to a third in 1931, with a total capacity of 6 MW. All three were decommissioned in 1980, and a single 3 MW generator was put on line in 1992.
- The Heart Mountain Power Plant was built in 1947, then upgraded with a new seasonally operated 5 MW turbine concurrently with the dam-heightening project.
- The Buffalo Bill Power Plant was built concurrently with the dam-heightening project and opened with three 6 MW generators in 1992.
- The Spirit Mountain Power Plant was opened in 1994, and seasonally operates a 4.5 MW generator.
Construction
With the authorization of the Shoshone Project in 1904, Buffalo Bill Dam became one of the earliest projects of the new Bureau of Reclamation. The ambitious project involved the construction of one of the first high concrete dams in the United States. Work began immediately, with drilling for geologic investigation starting in July 1904 and continuing for ten months. Work proceeded concurrently on the construction of an access road up the narrow canyon from Cody. The chosen contractor, Prendergast & Clarkson of Chicago, started work in September 1905, building a camp for workers and starting on a diversion dam, which was to divert the river into a wooden flume, through a tunnel and out through another flume to rejoin the river bed. Two men were killed in the construction of the tunnel. A June 1906 flood destroyed the flume. The delay caused the Bureau of Reclamation to suspend the contractor's contract and to call upon the contractor's bonding company, the U.S. Fidelity and Guaranty Company, to ensure the completion of the work. Little work was done until March 1907. Another flood in July damaged the diversion dam again. Working conditions were harsh, leading to the first strike in Wyoming's history in November, in which workers demanded and received three dollars a day from USF&G.USF&G delegated responsibility for the work to two new contractors, Locher and Grant Smith and Company, in March 1908. Work progressed more quickly, with the first concrete pours in April. Spring floods set the project back once again, causing concrete work to be suspended. Concrete work started again in March 1909, and despite more spring flooding that suspended work from July to September, work moved quickly. Another threatened strike was broken when Italian laborers were replaced with Bulgarian workers. Final concrete was poured in January 1910, with a final cost of $1.4 million. Seven construction workers were killed on the project.
Immediately after completion, the dam suffered from leakage through the outlet works, leading to low water elevations that exposed mudflats, which soon produced dense blowing dust. Corrective work to valves took until 1915. Problems with the north abutment's outlet works led to their abandonment in 1959. They were sealed in 1961. The reservoir began to lose capacity immediately as a result of the Shoshone's heavy silt load, and the material deposited at the head of the reservoir continued to blow when the reservoir was drawn down. Work continued on silt dikes and reforestation into the 1950s, but capacity is reduced from the reservoir's nominal capacity of to due to siltation.
The new reservoir covered hot springs at the forks of the Shoshone, similar to those found at Colter's Hell at the mouth of the Shoshone Canyon.