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Keyhole Unit
State: Wyoming
Region: Great Plains
Related Documents
Keyhole Unit History (35 KB)
Related Facilities
Related Links
Wyoming Area Office
Keyhole Reservoir
Weather Conditions (NOAA)
Precipitation
Belle Fourche River below Moorcroft, Wyoming (USGS)
Spring and Summer
Mountain Snowpack Maps for Missouri River Basin
Explanation of Palmer Drought Severity Index (Text)
Streamflows: Belle Fourche River below Keyhole Reservoir, Wyoming (USGS)
Upper Belle Fourche
Major Storage Reservoirs in the Belle Fourche River Basin
Palmer Drought Index Map
General
Keyhole Unit of the Pick-Sloan Missouri Basin Program, consisting of Keyhole Dam and Reservoir, is on the Belle Fourche River about 17 miles northeast of Moorcroft, Wyoming. Keyhole Reservoir is a multipurpose facility that provides storage for irrigation, flood control, fish and wildlife conservation, recreation, sediment control, and municipal and industrial water supply.
History
French trappers settled in the vicinity of Belle Fourche and, reportedly, engaged in fur trading with the Indians as early as 1854. Settlement in the area began with the gold rush to the Black Hills in 1876. Livestock became the principal industry in the general area. The Chicago and Northwestern Railroad reached the city of Belle Fourche in 1891 and, for the remainder of the 19th century, the city was considered the largest original shipping point for livestock in the United States.
Construction
Construction of Keyhole Dam began on June 29, 1950 , and was completed on October 25, 1952. Impoundment of water began in March 1952. Supplemental supply of stored water is provided to the Belle Fourche Project and the Belle Fourche-Wyoming Water Association which have 57,068 acres and 6,157 acres of irrigated land, respectively. Under present conditions, the integrated irrigation-dryland farms produce alfalfa, corn, small grains, pasture, and livestock. The principal products are used to provide a stable feed supply for stock-cow herds and sheep and fattening of cattle and lambs. Numerous facilities associated with outdoor recreation provided at Keyhole Reservoir include picnic grounds, campgrounds, boat ramp developments, swimming beach, and scenic overlooks. The recreation areas are administered by the Wyoming Recreation Commission. The warm-water fishery at the reservoir is maintained by the Wyoming Game and Fish Department. For specific information about Keyhole Reservoir click on the name below: On July 18, 1996 Wyoming kicked off the 100 year anniversary of the `Daddy of them All` Cheyenne Frontier Days. Known for such things as wide open spaces, rugged individualism, and being the only state to successfully imprison the bank robbing Butch Cassidy, Wyoming honors her roots every year with ten days of rodeos, concerts and general celebration. Essentially, Wyoming has not changed in the last 100 years; people still seek out her finer qualities of solitude and independence. `Except for Alaska there is no American state on which the passage of time and man has left so small an imprint as Wyoming.`(1) More than anything else the lack of water, average annual precipitation in the semiarid land is only about 14.5 inches, has prevented population growth. Coupled with the lack of water is the knowledge that even if water could be found, the rights to much of Wyoming`s water have been preempted by downstream states.(2) A notable example of Wyoming`s water rights issues is the Keyhole Dam and Reservoir in the northeastern corner of the state. Located in the Missouri River Basin, the Keyhole Unit is a part of the Pick-Sloan Missouri River Basin Project -- Cheyenne Division. The Unit is situated on the Belle Fourche River in Crook County, Wyoming, seventeen miles northeast of the town of Moorcroft. A multi-purpose unit, Keyhole Dam and Reservoir provides supplemental storage for the Belle Fourche Project located in South Dakota, limited irrigation in Wyoming, flood control, enhanced recreation, and fish and wildlife conservation.(3) The Unit is named for the Keyhole Ranch, the large ranch on which the dam site is located.(4) Wyoming has long been a desolate and unforgiving place with few settlers. Early exploration revealed it as a land of little water, making it merely an obstacle to be crossed and not enjoyed. Few on their cross-country travels appreciated the beauty of the unusual state, all they saw was the hot dry prairie that they had to cross to reach the waters and gold of California, Oregon and Washington. Until very recently Wyoming has been a have-not state with a very small population; location, resource limitations, high elevation, and aridity have combined to impede its growth. The country simply could not, and still does not sustain many people.(5) Despite a substantial land area of 96,988 square miles, Wyoming boasts the smallest population in the United States, 455,975 people as of the 1990 census.(6) Since primitive times, sparsity of population has been characteristic of the area. Paleo-Indian hunters and gathers were the first known human beings in the region. The first inhabitants of this unique land were few, estimates place the nomadic Indian population at no more then 10,000 when the Anglos arrived. Even the arrival of the Anglos did not denote permanence; the early hunters and trappers merely took what they needed off of the land before moving on. In spite of the lack of a stable population, Wyoming harbors many myths of the West: Lewis and Clark crossed her lands, as did George Armstrong Custer; the Oregon trail passed through her borders; and cowboys ruled the territory. It was the mountain men, however, that caught the eye of Wyoming residents. More than any other state, Wyoming has been identified as rendezvous country and as the home of the mountain men. The freedom, independence, and self-reliance of the trappers` life has been exaggerated, as has the economic importance and the color and romance of the annual gatherings, 1825-1840. The result is that many Wyomingites are still enamored of the mountain men. Jim Bridger, the most famous mountain man of them all, owned a trading post in the southwest corner of Wyoming. Bridger ranks as one of Wyoming`s six outstanding deceased citizens, while historians rate his fort second only to Fort Laramie in terms of importance. Wyoming`s greatest claim to fame, however, has always been her distinction of being `The Equality State.` In 1869, Wyoming did what no other government had ever done before, she granted women the right to vote. Considerations of justice notwithstanding, the majority of the legislature passed the suffrage bill because of its public relations value; they thought that it would advertise the territory and attract population. An additional argument for suffrage was that the opportunity to vote would attract women from the east to balance out the dominantly male population. The suffrage bill did not attract population, but it did give the state a distinction which lives on. In fact, in 1955 the Wyoming Legislature proclaimed Esther Morris, the first woman judge, the outstanding deceased citizen.(7) Wyoming is a land of many legends, but it has always had a scarce population and lacked of water. It is these two features of Wyoming that the Federal Government has attempted to address with projects such as the Keyhole Unit. But then there will always he those who prefer the pristine nature of the state. The Keyhole Unit was authorized as a part of the Missouri River Basin Project. The Pick-Sloan Missouri Basin Program was initially authorized by the Flood Control Act of 1944, which approved the general comprehensive plan for the conservation, control, and use of water resources in the entire Missouri River Basin. The Second Supplemental Appropriation Act, 1948 provided construction funds for the Keyhole Unit.(8) In the fall of 1917, the United States Reclamation Service in response to a petition from the water users association, investigated possible additional storage sites for the Intake Canal and Johnson Lateral, located on the Belle Fourche Project. In the 1930`s the Army Engineer Corps conducted investigations in the Missouri River Basin. The results of these investigations failed to identify any possibilities for a new multi-purpose reservoir which would justify the cost involved. Uncertain water supply, disadvantageous locations, and excessive construction costs presented problems. A basin-wide investigation of the Cheyenne River Basin was begun in the late 1930`s by the Bureau of Reclamation. The survey included a study of the Belle Fourche River Basin. The final site on which Keyhole Dam has been constructed was a result of the latter investigation.(9) Traversing the Belle Fourche River, Keyhole Dam, is the primary feature of the Keyhole Unit; the Dam forms a reservoir with a total capacity of 340,100 acre-feet and water surface of 13,686 acres. A zoned earthfill structure, the Dam has a crest length of 3,420 feet, including the 2,120-foot dike extension of the right bank, and a maximum structural height of 168 feet. The spillway, a vertical slot-type uncontrolled concrete-crested structure with a concrete-lined open channel, is located in the dike near the right abutment of the dam. Topped by a concrete bridgedeck on the crest of the dam, the spillway has a crest length of 19.25 feet. Discharge capacity of the spillway is 11,000 cubic feet per second. A concrete-lined horseshoe-shaped tunnel 9.5 feet wide by 8.25 feet high through the left abutment houses the outlet works. Two vertical lift, high pressure, hydraulic slide gates control release capacities of about 1,480 cubic feet per second.(10) Initial work on the Keyhole Unit began in March 1949, with construction of the Government Camp located on site. The Camp was finished later that same year and work was scheduled to begin on the dam March 1, 1950, with a completion date of June 30, 1952.(11) However, the contract for construction of Keyhole Dam was not awarded until June 8, 1950, delaying the start of construction until July 6, 1950. The Contract was awarded to Knisely-Moore Company of Douglas, Wyoming.(12) Work proceeded on schedule and water storage in Keyhole Reservoir began February 12, 1952, after placement of the temporary bulkhead in the inlet structure of the outlet works. The permanent bulkhead was installed six weeks later on March 26, 1952, at which point the outlet tunnel was closed. Even though the Dam was still under construction, the first water releases from the Reservoir were made on August 1, 1952. Subsequently, the final spillway concrete was placed and the hoist house completed, signaling the end of the concrete work on the Keyhole Unit. Nearly six weeks after the final concrete had been placed, on October 25, 1952, Keyhole Dam was completed by Knisely-Moore Construction Company; the Bureau of Reclamation accepted the dam the same day. At the beginning of December 1952, the construction field office was closed by the Bureau of Reclamation. The files and equipment were moved to Pactola Dam, South Dakota, where future construction matters would be handled. Closing of the field office preceded the relocation of the temporary residences, occupied during construction to the Pactola construction office site--Rapid Valley Unit.(13) Keyhole Reservoir began to release waters on April 20, 1953, to satisfy the prior downstream rights of the Belle Fourche Irrigation District. Later the same year, on June 30, 1953, the official transfer of Keyhole Dam and Reservoir facilities from construction status to operation and maintenance (O & M) status occurred.(14) All O & M was transferred to the Pactola Unit beginning January 1, 1959, after discontinuing the services of the Resident Superintendent at the close of the proceeding year.(15) Flood control benefits in Keyhole Reservoir are provided by use of an exclusive flood control capacity of 140,462 acre-feet and a surcharge capacity of 294,810 acre-feet for a total flood capacity of 435,810 acre-feet and, as of 1998, the reservoir has reduced flood damages by about $3.6 million.
Plan
Keyhole Reservoir provides a supplemental water supply to the 57,068-acre Belle Fourche Project located about 146 miles downstream in western South Dakota. Water for the project is released into the Belle Fourche River and then diverted for project purposes. Supplemental water also is furnished to the Belle Fourche-Wyoming Water Association for approximately 7,523 acres of privately developed land and associated facilities around the reservoir and downstream from the dam for a distance of about 25 miles. Contractual arrangements for furnishing water to a housing development near the reservoir are pending. The apportionment of inflows to Keyhole Reservoir is set forth in the provisions of the Belle Fourche River Compact negotiated by the States of Wyoming and South Dakota and confirmed by the Congress in 1944 (58 Stat. 94). The compact provides that the unappropriated flow of the Belle Fourche River, as of the date of the compact, shall be allocated 10 percent to Wyoming and 90 percent to South Dakota, provided that Wyoming shall have unrestricted use for domestic and stock water purposes. Wyoming can purchase 10 percent of the storage capacity of Keyhole Reservoir to regulate its portion of the unappropriated water. The primary feature of the unit is Keyhole Dam across the Belle Fourche River, which forms a reservoir with a total capacity of 334,200 acre-feet and water surface of 13,700 acres. Keyhole Dam is a zoned earthfill structure with a maximum structural height of 168 feet, and a crest length of 3,420 feet, including the 2,120-foot dike extension of the right bank. The outlet works consists of a concrete-lined horseshoe shaped tunnel 9.5 feet wide by 8.25 feet high through the left abutment. Release capacities of about 1,480 cubic feet per second are controlled by two vertical lift, high-pressure hydraulic slide gates. Keyhole Dam and Reservoir are operated and maintained by the Bureau of Reclamation.
Contact
Contact
Title: Public Affairs OfficerOrganization: Great Plains Region
Address: 2021 4th Avenue North
City: Billings, MT 59101
Fax: 406-247-7604
Phone: 406-247-7610
