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Angostura Division
State: South Dakota
Region: Great Plains
Related Documents
Angostura Division Project History (48 KB)
Related Facilities
Related Links
Dakotas Area Office
Angostura Reservoir
Angostura Reservoir
Edgemont, South Dakota
Cheyenne River below Angustora Dam, South Dakota (USGS)
Cheyenne River at Wasta, South Dakota (USGS)
Explanation of Palmer Drought Severity Index (Text)
Angostura Reservoir
Middle Cheyenne - Spring
Custer, South Dakota
Palmer Drought Index Map
General
The Angostura Unit of the Pick-Sloan Missouri Basin Program is in the Great Plains region at the southeast edge of the Black Hills in southwestern South Dakota. Angostura Dam and Reservoir, located on the Cheyenne River about 9 miles southeast of Hot Springs, South Dakota, provides multipurpose benefits, including irrigation, flood control, fish and wildlife conservation, recreation, and sediment control. The unit lies within Custer and Fall River Counties of South Dakota.
History
Dry farming by settlers in the Angostura Unit area began about 1880. The gold rush to the Black Hills in 1876, followed by several years of adequate precipitation and accompanying good crop production, stimulated development in the area. Severe drought conditions and heavy infestations of grasshoppers in the late 1880`s contributed to mortgage foreclosures, resulting in fewer landowners with larger land holdings.
Construction
Construction of Angostura Dam began on August 23, 1946, and was completed on December 7, 1949. The first delivery of irrigation water was made in 1953. A full supply of irrigation water is provided to the 12,218 acres of irrigable land. Alfalfa and corn are the principal crops, along with wheat, barley, oats, pasture, and forage. Activities associated with outdoor recreation around Angostura Reservoir include picnic sites, campgrounds, marinas, swimming beaches, and areas for seasonal use cabins. All recreation areas and facilities, including the fishery in the reservoir, are administered by the South Dakota Department of Game, Fish, and Parks. For specific information about recreational activities click on the name below. http://www.recreation.gov/detail.cfm?ID=1161 There is no exclusive flood capacity in Angostura Reservoir; however, flood control benefits are provided by the use of conservation capacity, as available, and the surcharge capacity of 56,360 acre-feet above the top of the radial spillway gates. As of 1998, Angostura Reservoir has prevented $21,000 in flood damages. Silt -- the four letter word that echoes like a curse along the valleys and bench lands of the Great Plains. Like an incurable disease, silt can shorten the life of a water project. It is a condition the South Dakota`s Angostura Unit lives with. In the 1930s, federal engineers drew up plans for a reservoir in the shadow of the Black Hills along South Dakota`s Cheyenne River. One of the Missouri River`s many tributaries, the Cheyenne ranks fifth for the amount of silt it carries into the `Big Muddy.` Engineers then would only guarantee fifty years of storage before silt would become a serious problem. Choosing to ignore what awaited them, a group of South Dakota farmers persuaded the Federal Government to build a water project. When the Government agreed to build, it opened up the possibilities of irrigated agriculture to a group of South Dakota dryland farmers victimized by the Dust Bowl. Angostura is the first started and completed unit of the Pick-Sloan Missouri Basin Program, providing irrigation, flood control, fish and water conservation, and recreation. In 1999, the Unit will have triumphed over pre-construction predictions to celebrate its fiftieth birthday. A countdown will begin that will be a turning point in the life of a water project and the people it serves.(1) One-time South Dakota State Engineer, Homer Derr, carried the word Angostura north from a Bolivian dam project. Angostura means `narrows` in Spanish, and is also a South American shrub used as an anti-malarial remedy. Three other dams in the Western Hemisphere share the name Angostura: one near Cochamba, Bolivia, one in northeastern Sonora in Mexico, and a diversion dam on Reclamation`s Middle Rio Grande Project near Belem, New Mexico.(2) On the southeast edge of the Black Hills, Angostura Dam and Reservoir straddle the Cheyenne River near the mouth of the Red Canyon. The reservoir extends 17 miles in length along the Cheyenne River and 7.6 miles up Horsehead Creek, a major tributary. Unit lands extend along the river from the damsite to a point 25 miles downstream, irrigating 12,154 acres in Fall River and Custer counties along the way. Smooth, gently slopping terraces rise 50 to 250 feet above the river, but are dissected into flats by deep, lateral stream valleys. About 78 percent of the irrigable lands lie south of the river in an area known locally as W.G. Flat. The remaining 22 percent are on the north side in the Harrison Flat. The nearest town, Hot Springs, is about six miles southeast of the dam.(3) The climate is semiarid, with hot, summer days and cool nights. A growing season of 132 days pushes farmers to get their corn and alfalfa hay in early. Annual precipitation is 17.5 inches with 78 percent of that amount falling from April through September. The maximum temperature is 112 degrees F while the minimum is -41 degrees F. January is the coldest month of the year and July is the hottest.(4) The Black Hills country furnished physical nourishment and spiritual support to two native American tribes over the past 500 years. Sometime between 1550 and 1600, the Arikara, or Ree, Indians moved into the Missouri River Valley and present-day South Dakota. Drought forced their migration from the central plains of Nebraska and Kansas. The Arikara grew corn, squash, beans and tobacco, but other tribes knew them as the `corn-eaters.` Attacking bands of Teton Lakota and small pox epidemics decimated the Arikara by the 1790s. By the 1820s, the remaining 500 Arikara moved into North Dakota joining the Mandan tribe.(5) The departure of the Arikara ushered in the `Golden Era` of the Lakota along the Missouri Basin. Freed by the mobility of the horse and employing their talents as hunters and warriors, the Lakota ruled uncontested over their domain. The Black Hills, or Paha Sapa in Lakota, remains the sacred center of Lakota lands and lives. The Lakota fought incoming whites, before they were out-gunned and out-manned by the United States Army. The Angostura Reservoir is within lands ceded to the United States by the great Sioux nation in the 1868 Treaty of Fort Laramie. The Cheyenne River forms the northeast corner of the Pine Ridge Indian Reservation and the southern boundary of the Cheyenne River Sioux Indian Reservation.(6) The discovery of gold in the Black Hills in 1874 lured the first large influx of whites to the region. Several cattle companies drove their herds in from other states to feed on the open, unfenced range. A few companies established themselves while others sold out to incoming homesteaders. By the turn-of-the-century, homesteads dotted the land where cattle roamed two decades previous. A settler`s shack could be found on almost any quarter-section, and each family kept a few cattle. Some grew discouraged, selling their holdings to neighbors, or turning the land over to the county to pay off their taxes. The successful and persistent gradually acquired more acreage. In their wake, the original homesteaders left a unfortunate legacy of soil erosion. Their teams broke acres of native sod, exposing the soil and leaving the ground and their crops vulnerable to wind erosion.(7) The Federal Government completed the Angostura Unit, but Homer Derr is the unit`s father. During the century`s second decade, as other South Dakotans fought drought and dust, the former state engineer was in Bolivia helping to build an earthfill dam. Back in South Dakota in 1913, the state hired Derr to conduct a hydrographic survey of the Cheyenne. Once he reached a gorge known as Jackson narrows, he noticed a resemblance to a similar landmark back in Bolivia. In his report, Derr selected the Jackson Narrows as the best location for a dam, because of its proximity to the irrigable lands, and rechristened the area `Angostura.`(8) Based on Derr`s reconnaissance, in 1917 the South Dakota state legislature appropriated funds for one-half the cost of a survey under the direction of the United States Reclamation Service (USRS). In a subsequent report, Reclamation`s C.T. Pease, estimated a Cheyenne River project could irrigate a maximum of 76,000 acres at a minimum of $150 to $160 per acre. The high price frightened off the Federal Government, and Reclamation declared Angostura unfeasible. Eleven years later in 1928, the U.S. Army Corps of Engineers investigated the entire Missouri River watershed. Their survey reduced the number of potential irrigable area along the Cheyenne from 51,000 to 61,000 acres and raised the estimated costs to $173 to $181 an acre.(9) From 1931 until decade`s end, meager moisture produced only crop failures across South Dakota. The average 160-acre homestead was too small to offer a living to dryland farmers. A 1936 study found that of the existing 41 farmsteads on proposed project lands, owners occupied 20 lots, tenants rented 14 units, and seven had been abandoned. Farm homesteads came in sizes ranging from small shacks to six-room houses. As the number of farmers dwindled, the size of the farms increased. By the close of the 1930s, an average single family farm was a little more than 320 acres. The remaining farmers still kept the dream of a dam across the Cheyenne alive. A 1939 Reclamation study of the Cheyenne noted the persistent local interest in water development, while estimating 16,200 acres of nearby land were irrigable.(10) By 1939, the government had purchased 75 percent of ravaged farm land under the Wheeler-Case Act. Named for South Dakota Republican Representative Francis Case and Democratic Senator Burton K. Wheeler of Montana, the Wheeler-Case Act authorized the Federal Government to develop irrigation and return land to private hands. The Rapid City Journal noted `some persons in the foothills` who saw Wheeler-Case as `a communistic trend in long-term government ownership on the land.` Still, both the press and public realized Wheeler-Case was agriculture`s only chance in the area. Congressman Francis Case captured the yearning of his constituents in a letter to Reclamation Commissioner John Page in 1940: `I was hardly prepared for the pathetic, desperate hopes that are being pinned on the present work, from all classes of people.`(11) Citizens in Case`s Second Congressional District besieged the federal government into including a Black Hills water project in the Water Conservation and Utilization (WCU) Act of August 11, 1939. The Farm Security Administration and the Department of Agriculture also showed interest in rehabilitating lands and resettling distressed farmers into that region. Behind the scenes, from 1939 to 1942, Case cajoled and begged Reclamation Commissioner John C. Page to build water projects in his state. Once, he went as far as sending Commissioner Page a state highway map indicating potential damsites in blue crayon.(12) A condition in the WCU Act, as amended October 14, 1940, limited funds to $1,000,000 per project. This, and the lack of a suitable power market in the immediate area, held up the project until it could no longer come under the provisions of the WCU Act. The Works Progress Administration (WPA) stepped in and funded surveys and foundation explorations to complete a construction estimate. Reclamation calculated the cost of construction at $3.9 million, of which, the WPA and Civilian Conservation Corps (CCC) would pay $2 million with the balance picked up by Reclamation. Congress approved the WCU Act on March 6, 1941, following a joint recommendation from Secretary of Interior Harold L. Ickes and Secretary of Agriculture Claude R. Wickard. Ickes called Angostura a `work relief` irrigation project that would solve the problems of local unemployment, interstate movement of farmers, and stabilize the agricultural economy. By 1942, basic design and construction data was in place. Case expressed his appreciation to Page: `I doubt if anything will ever happen to me which will ever seem as important or as good as the final approval on the Angostura Project.`(13) Case`s gratitude was premature, as Angostura was one of many reclamation projects marking time during World War II. The unlikely partnership between Reclamation and the Corps of Engineers, known as the Pick-Sloan Missouri Basin Project, provided the legislation that led the way to the first day of construction. The outline of the Angostura Project is included in the Missouri River Basin plans as set forth in Senate Document 191, 78th Congress, 2nd Session. These plans were re-authorized by Congress in section 9 of the Flood Control Act of 1944 (58 Stat. 891).(14) The Utah Construction Company successfully bid to complete the dam and reservoir on May 28, 1946. Utah Construction`s bid of $4.2 million was below Reclamation`s estimate of $4.9 million. Construction began September 11, 1946, with the contractor stripping material for placement in the earth embankment. Excavation of the embankment core trench and stripping operations carried on simultaneously into December. Approximately 30,000 cubic yards of excavated gravel and rock from the core trench formed the embankment.(15) Reclamation`s leadership realized that despite Angostura`s small size it carried a great weight as the first of the Bureau`s Pick-Sloan assignments. At ground breaking ceremonies on August 23, 1946, Assistant Commissioner William E. Warne heaped praise on the work ahead. He declared it held `the number one place today in the roster of reclamation projects` because of the scope and significance of the Missouri River Basin plan. He explained, `Although the Angostura will not be a giant like Grand Coulee nor a behemoth like Boulder (now Hoover Dam), but it will have an important role in the regeneration of your valley.` To make sure this first cog in Pick-Sloan ran smoothly, Reclamation selected H.V. Hubbell as project engineer. Hubbell served as construction engineer for the Fresno Dam on the Milk River Project a decade earlier.(16) Accommodations for the contractor`s employees were luxurious considering the location and the economic constraints just after World War II. The camp consisted of 25 one and two bedroom houses, seven barracks to house 300 single men, a mess hall, offices, machine shop, and a warehouse. All facilities were in place by mid-December 1946. During peak operations in the summer and fall of 1947, Utah Construction employed 400 men, before eventually cutting back to a hundred for the winter. A high turnover in men during the first two years handicapped the dam`s progress. Besides completing the dam contract, Utah Construction built access roads branching from the main highway to the dam site and from the dam to the rock quarry. They also completed two bridges, one upstream and one downstream, to connect the camp to the outside world.(17) The Angostura Dam is a 187-foot-high combination concrete gravity and earthfill embankment. Angostura reservoir holds a total capacity of 130,000 acre feet with an active capacity of 82,400 acre-feet and dead storage of 48,300 acre-feet. The dam`s crest length is 2,030 feet with the concrete section measuring 970 feet in length and the earth embankment 1,060 feet long. The concrete portion features a gated spillway section located in the river channel and two non-overflow sections, one extending to the left abutment and one abutting the earth embankment extending to the right abutment. The maximum width of the concrete dam is 220 feet including the spillway apron. A 25-foot-wide roadway runs across both sections. The contractor`s placed the first bucket of concrete on July 28, 1947. Building from that bucket, the dam soon held a total of 274,191 cubic yards of concrete. River water circulating through embedded pipe coils cooled the concrete after placement. A cableway system transported buckets of concrete for placement in the dam. Reclamation believed the cableway was "the most vital equipment" at Angostura. Despite "some defects" soon after installation, the cableway ran without any trouble for the next two years.(18) The dam`s concrete overflow spillway is in line with the river channel. Five 50-foot-wide by 30-foot-high radial gates control the spillway. Any overflow is dissipated by a specially designed slotted-type, large-radius spillway bucket set within the retaining walls at the toe of the dam. The bucket proved to be more economical than conventional spillway aprons. The spillway`s peak discharge capacity is 217,000 cfs with the reservoir water surface at elevation 3198.1. The river outlet works consist of a 4.5-foot-diameter steel conduit through the concrete dam section. A four-foot-square high pressure gate in the valve house in the downstream end controls the outlet. Discharge capacity is 590 cfs.(19) The earthfill embankment begins at the right end of the concrete section and extends 1,063 feet into the right abutment. The embankment is a zoned, rolled, earthfill structure with an impervious core of clay, sand, and gravel. Rock riprap protects the upstream and downstream faces of the embankment. A cutoff trench under the embankment section intercepts layers of sand and gravel, providing a positive cutoff to bedrock. Zone 1 embankment material is a shovel-cut mixture of stratified layers of clay, silt, sand and gravel taken from a pit 4,000 feet from the dam. Most of the Zone 2 sand and gravel came from the cutoff trench excavation. A borrow area 2,500 feet upstream from the dam provided the rest of the material. A 16-inch layer of rock fines prevented Zone 2 material from washing through the riprap. The riprap came from a location 1,400 feet upstream from the dam.(20) Water from the reservoir travels through a 30-mile-long main canal extending from the dam along the south edge of the unit. The canal crosses under the Cheyenne River through a 9,800-foot-long inverted siphon to the river`s north bank. First delivery came in 1953. Irrigation came to the entire unit three years later. The canal`s cross section averages a bottom width of 14 feet with 2:1 side slopes and a normal water depth of 5.2 to 5.5 feet. Average annual releases to unit lands is 40,000 acre-feet. This provides an average on-site farm delivery of 2.5 acre-feet of water per acre. Thirty-nine miles of laterals and 21 miles of open and closed drains serve individual farms. Peter Kiewit Sons of Rapid City constructed all canals, laterals and drains from 1951 to 1953.(21) On March 16, 1948, at 9:30 a.m. six months of uncertainty and tragedy for the project began. At that moment, floodwaters tore through the contractor`s interlocking sheet pile cofferdam. The gush of water carried away three of the contractor`s men while inundating blocks 12 and 13 in the concrete section and the downstream area. Divers brought out from San Francisco searched for the men over the next four days. Murky silt resulted in poor underwater visibility, forcing the contractor to call off the search. Utah Construction pumped out the flooded area, removing the silt carefully to avoid mutilation of the missing men. The weather fought rescue efforts between March and August, as floods washed out the area six times. On August 10 and 11, workers discovered the remains of the three men buried in the foundation section.(22) On September 28, 1949, the night before the official dedication, Reclamation Commissioner Michael W. Straus spoke to the South Dakota Reclamation Association. Straus thanked the farmers and citizens of Hot Springs who first asked the Federal Government`s help, `without your cooperation, the Bureau of Reclamation could never have gone ahead as rapidly as it has.` Total cost of the completed unit came to $15,383,863.(23)
Plan
The primary function of the Angostura Unit is to impound and deliver a full supply of irrigation water for production of forage and grain crops. The unit lands, consisting of 12,218 acres extending along the Cheyenne River approximately 24 miles downstream from the dam, are served by the Angostura Canal. The canal has a design capacity of 290 cubic feet per second. With a 29.7-mile-long alignment along the southerly edge of the unit lands, the canal crosses the Cheyenne River through a 9,800-foot-long inverted siphon to the north side of the river. Unit lands are served by 39 miles of laterals and 34 miles of open and closed drains. The prime features of the unit are Angostura Dam across the Cheyenne River, and Angostura Reservoir. The dam is a composite type, consisting of a concrete gravity structure and an earth embankment. The concrete portion of the dam comprises a gated spillway section located in the river channel and two nonoverflow sections, one extending to the left abutment and one abutting the earth embankment extending to the right abutment. The dam has a crest length of 2,030 feet; the concrete section is 970 feet long and the earth embankment 1,060 feet long, with a structural height of 193 feet and a hydraulic height of 136 feet above the riverbed. The spillway is an overflow section in the concrete portion of the dam, controlled by five 50- by 30-foot radial gates. Discharge capacity is 247,000 cubic feet per second. The river outlet works consists of a 4.5-foot diameter steel conduit through the concrete dam section, controlled by one 4-foot-square high-pressure slide gate in the valve house at the downstream end. Discharge capacity is 590 cubic feet per second. The main canal outlet works for irrigation water delivery consists of a 6-foot-diameter steel conduit through the concrete dam terminating in a valve house, a stilling basin, and canal headworks at the downstream end. Releases into the 290-cubic- foot-per-second-capacity canal are controlled by two 3.5-foot-square high-pressure slide gates in the valve house. Angostura Unit, including Angostura Dam and Reservoir and the associated project irrigation facilities, has been operated and maintained by the Angostura Irrigation District, since January 1, 1968.
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