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Pactola Dam
Pactola Dam

Statistics

General

  • Region (Map) : .................. Great Plains
  • State (Map) ....................... South Dakota
  • County ............................... Pennington
  • Project: ............................... PSMBP-Rapid Valley Unit, Cheyenne Divsion
  • Dam type: ........................... Earthfill
  • Location: ............................ 15 mi W of Rapid City
  • Watercourse: ..................... Rapid Creek
  • Reservoir: ........................... Pactola
  • Construction Date: ........... 1952-1956
  • Modified: ............................. 1987
  • National ID Number ......... SD01139
  • Hydrologic Unit Code .....

Dimensions

Hydraulics

  • Normal Water Surface Elev: ............... 4580.2 ft
  • Hydraulic Height: ................................. 199.5  ft
  • Service Spillway Type:
  •    Uncontrolled  Crest    ............................... Yes
  •    Morning-Glory ............................................ No
  •    Crest Length    ..................................... 425.0 ft
  •    Gated      ....................................................... No
  • Capacity at Elev:  4651.7 ft,............... 245,000 cfs
  • Auxiliary Spillway ......................................... No
  •     Capacity at Elev.   .................................... NA
  • Outlet Works Capacity at
  •     Elevation  4633.7 ft.,  ....................... 1,150 cfs

Hydrology

  • Drainage Area: ........................................... sq mi
  • Hydrometeorological Report (HMR)     HMR x
  • Flood Type: ............................... General
  • Storm Duration: .......................................  hrs
  • Probable Maximum Flood (PMF) Report:
  •   Peak Inflow: ..................................  cfs
  •   Inflow Volume: ........................  acre-ft
  •   Flow Duration: ......................................0 days
  •   PMF Routing MWS Elev.: ................. x.0 ft
  •   Initial Routing Elev: ............................ x.0 ft
  •   Study Date: xx 19

Power Generation

Narration

 

Geology

Pactola Dam is situated at a point along Rapid Creek where the valley narrows and the creek has cut through a resistant, northwest trending ridge.  Rocks at the dam consist of a complex series of schists, slates and amphibolites lying in nearly vertical beds which strike in a northwest direction.  There is a small fold in the right abutment that modifies the strike of the beds and causes the axis of the dam to cross some beds twice.  The schistosity for the most part parallels the original bedding.  The amphibolite schist rocks are hard, jointed and usually weathered to shallow depths.  The slate beds contain abundant iron pyrite which weathers readily above the water table.

Links

 | Recreation |

 | Dams Located by State | USBR South Dakota Dams | North Great Plains Region Dams |

 | Owner:  Bureau of Reclamation, Dakotas Area Office,
                   PO Box 1017, Bismarck, ND 58502-1017, (701) 250-4242

 | Operator:  City of Rapid City Public Works Department,
                       Rapid City, South Dakota

 
 

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