Country United States Status Operational Height 59 m Length 975 m Create Angostura Reservoir | Purpose Irrigation Type of dam Embankment, earth-fill Opened 1949 Total capacity 240.7 million m³ Construction began 1946 | |
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Location Fall River County, South Dakota Opening date 1949; 68 years ago (1949) Owner United States Bureau of Reclamation | ||
Angostura Dam is an embankment dam across the Cheyenne River in Fall River County in southwestern South Dakota in the United States, about 75 miles (121 km) south of Rapid City. The dam consists of an earth-fill embankment with a concrete spillway section, 193 feet (59 m) high and 3,199 feet (975 m) long; it withholds the 195,121-acre-foot (0.240678 km3) Angostura Reservoir. The dam was conceived as early as 1913, but it was not until the 1930s when a regional drought caused crop failures that the project received widespread support from farmers. Built from 1946 to 1949, the dam is part of the Angostura Division of the Pick-Sloan Missouri Basin Program, and is operated by the U.S. Bureau of Reclamation.
Map of Angostura Dam, Hot Springs, SD 57747, USA
The dam's primary purpose is to store water for the irrigation of 12,218 acres (4,944 ha) of project lands. The service area lies along 24 miles (39 km) of the Cheyenne River below the dam, and is supplied by the Angostura Canal, which has a diversion capacity of 290 cubic feet per second (8.2 m3/s). The dam and reservoir regulate runoff from an area of 9,034 square miles (23,400 km2). The reservoir has a conservation storage capacity of 138,761 acre feet (0.171159 km3), with an extra 56,740 acre feet (0.06999 km3) of surcharge, flood-control storage. Flood water releases are controlled by a spillway with five radial gates, which can pass up to 247,000 cu ft/s (7,000 m3/s).
Angostura Reservoir is one of the only large lakes in western South Dakota. With 36 miles (58 km) of shoreline and 4,706 acres (1,904 ha) of water, the reservoir is stocked with several species of fish, including walleye, smallmouth bass and crappie.