Pactola Dam is an

embankment dam An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface and ...

on Rapid Creek in Pennington County,

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota peo ...

, about west of

Rapid City Rapid City ( lkt, link=no, Mni Lúzahaŋ Otȟúŋwahe; "Swift Water City") is the second most populous city in South Dakota and the county seat of Pennington County. Named after Rapid Creek, where the settlement developed, it is in western So ...

. The dam was completed in 1956 by the U.S. Bureau of Reclamation to provide flood control, water supply and recreation. Along with the nearby Deerfield Dam, it is part of the Rapid Valley Unit of the Pick-Sloan Missouri Basin Program.

U.S. Route 385 U.S. Route 385 (US 385) is a spur of U.S. Route 85 that runs for 1,206 miles (1,941 km) from Deadwood, South Dakota to Big Bend National Park in Texas. Route description , - , TX , 545 , 877 , - , OK , 36 , 58 , - , CO , 317 , 510 ...

runs along the crest of the dam. The dam forms

Pactola Lake Pactola Lake is the largest and deepest reservoir in the Black Hills, located 15 miles west of Rapid City, South Dakota, United States. Constructed in 1952, the dam and waters are managed by the Bureau of Reclamation, with the surrounding land m ...

, which at over is the largest and deepest body of water in the Black Hills.

History

The dam is named for the town of Pactola which today is flooded under the reservoir. The town's name originated from the

Pactolus Pactolus ( el, Πακτωλός), now named Sart Çayı, is a river near the Aegean coast of Turkey. The river rises from Mount Tmolus, flows through the ruins of the ancient city of Sardis, and empties into the Gediz River, the ancient Hermus. ...

river in ancient

Lydia Lydia (Lydian language, Lydian: ‎𐤮𐤱𐤠𐤭𐤣𐤠, ''Śfarda''; Aramaic: ''Lydia''; el, Λυδία, ''Lȳdíā''; tr, Lidya) was an Iron Age Monarchy, kingdom of western Asia Minor located generally east of ancient Ionia in the mod ...

(modern day

Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...

), which was known for the gold found in its bed. The name was given to the valley by miners after the

Black Hills Gold Rush The Black Hills Gold Rush took place in Dakota Territory in the United States. It began in 1874 following the Custer Expedition and reached a peak in 1876–77. Rumors and poorly documented reports of gold in the Black Hills go back to the early ...

of 1874–1877. The gold rush directly led to the

Great Sioux War of 1876 The Great Sioux War of 1876, also known as the Black Hills War, was a series of battles and negotiations that occurred in 1876 and 1877 in an alliance of Lakota Sioux and Northern Cheyenne against the United States. The cause of the war was the ...

(Black Hills War), in which the US Army drove the Lakota Sioux and

Cheyenne The Cheyenne ( ) are an Indigenous people of the Great Plains. Their Cheyenne language belongs to the Algonquian language family. Today, the Cheyenne people are split into two federally recognized nations: the Southern Cheyenne, who are enroll ...

people from their traditional lands in the Black Hills. Pactola was eventually left behind by the miners in search of richer gold deposits, but a few residents stayed in the town until the 1950s, when the Bureau of Reclamation began to purchase and clear property in preparation for building a dam and reservoir. The Pactola Dam was built as part of the Rapid Valley Unit, in turn a part of the Pick-Sloan Missouri Basin Program. The purpose of the project was to provide water for irrigation and domestic consumption in the fast growing town of Rapid City where the existing water supply, mainly from wells, was being exhausted by heavy use. The Bureau of Reclamation conducted its first studies for a dam on Rapid Creek in 1937, and determined the final site on November 14, 1939. However, there was a controversy over whether the Pactola or Deerfield Dam should be built first, and due to this delay, most of the initial Congressional funds for the Rapid Valley Unit were moved to an irrigation project in Wyoming instead. The Bureau of Reclamation eventually decided to build Deerfield first, completing it in 1948. The Pactola Dam was authorized under the

Flood Control Act of 1944 The Pick-Sloan Flood Control Act of 1944 (P.L. 78–534), enacted in the 2nd session of the 78th Congress, is U.S. legislation that authorized the construction of numerous dams and modifications to previously existing dams, as well as levees acros ...

but construction was put on hold in part due to

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. In 1948 the Rapid Valley Water Conservancy District petitioned the Bureau of Reclamation to build Pactola, as Deerfield alone was unable to provide enough water for the area's needs. In 1949 Rapid City also requested a right to water stored in a future Pactola Reservoir, some of which would be used at

Ellsworth Air Force Base Ellsworth Air Force Base (AFB) is a United States Air Force base located about northeast of Rapid City, South Dakota, just north of the town of Box Elder, South Dakota, Box Elder. The host unit at Ellsworth is the 28th Bomb Wing (28 BW). Assi ...

. Construction of Pactola Dam began on November 25, 1952. As many as 200 people worked on at the dam site at any one time; no deaths occurred during the four years of construction but there were numerous injuries due to the hazardous terrain. All the buildings in Pactola were moved or demolished by the Bureau of Reclamation before the reservoir was allowed to fill. The dam was completed on August 15, 1956, and the first water delivery from Pactola Reservoir was on May 1, 1958. During the Black Hills Flood of 1972, Pactola Dam stored most of the floodwater coming down from upstream, but the heaviest rains occurred in the part of the Rapid Creek watershed below the dam, resulting in catastrophic flooding in Rapid City that killed 238 people. Nonetheless, in 1987 the dam was raised and the spillway enlarged in order to provide better protection against future floods.

Specifications

The Pactola Dam consists of a main earth-filled dam with two auxiliary dikes on the northern side. The main dam stands high as measured from the foundation and is above the streambed. The combined length of the dam and dikes is , and contain of material. The crest of the dam is at an elevation of above sea level and the spillway crest is . The spillway is an un-gated concrete overflow structure located in between the main dam and auxiliary dikes, and has a capacity of . The dam also has

outlet works A gatehouse, gate house, outlet works or valve house for a dam is a structure housing sluice gates, valves, or pumps (in which case it is more accurately called a pumping station). Many gatehouses are strictly utilitarian, but especially in the n ...

that can release . The long Pactola Lake has of shoreline and covers at normal water levels. The reservoir has a capacity of , of which is active or usable storage. Normal water surface elevation is . The reservoir controls runoff from a drainage area of . The small town of Silver City is located at the upstream (western) end of the reservoir.

Recreation

The

U.S. Forest Service The United States Forest Service (USFS) is an agency of the U.S. Department of Agriculture that administers the nation's 154 national forests and 20 national grasslands. The Forest Service manages of land. Major divisions of the agency in ...

operates the Pactola Visitor Center, which is located at the south end of Pactola Dam. The center provides interpretive exhibits, travel information and a scenic view of the reservoir. The Pactola Pines Marina is located at Custer Gulch on the south shore of the reservoir and was opened in 2000. The privately owned marina has a capacity of 200 boats and has fishing boats, canoes and paddleboards for rent. The reservoir is known for its large

lake trout The lake trout (''Salvelinus namaycush'') is a freshwater char living mainly in lakes in northern North America. Other names for it include mackinaw, namaycush, lake char (or charr), touladi, togue, and grey trout. In Lake Superior, it can also ...

Brown trout The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morph ...

are found in Rapid Creek both upstream and downstream of the dam; the creek directly below the dam has been described as an "exceptional" fly fishing location.

Climate

References

External links