Sensitivity of ground water to contamination in Lawrence County, South Dakota

2000 ◽  
Keyword(s):  
South Dakota ◽  
Ground Water ◽  
Lawrence County

scholarly journals Topographic Map Analysis of High Elevation Black Hills Through Valleys Linking Spearfish and Rapid Creek Headwaters Valleys, Lawrence County, South Dakota, USA

2017 ◽  
Vol 10 (1) ◽  
pp. 8
Author(s):  
Eric Clausen
Keyword(s):  
South Dakota ◽  
Drainage Basin ◽  
Water Source ◽  
High Elevation ◽  
Black Hills ◽  
Topographic Map ◽  
Drainage Basins ◽  
Converging Channel ◽  
Lawrence County ◽  
Map Analysis

The Spearfish-Rapid Creek drainage extends from elevations greater than 7130 feet (2173 meters) roughly in a north direction across the northern Black Hills upland to where it becomes the Spearfish-Whitewood Creek drainage divide at an elevation of approximately 6440 feet (1963 meters) and separates north-oriented Spearfish Creek headwaters from southeast- and east-oriented Rapid Creek headwaters. This study used detailed topographic maps to investigate through valleys (and wind gaps) now crossing the Spearfish-Rapid Creek drainage divide, which is one of the Black Hills’ highest drainage divides. Through valley (or wind gap) floor elevations were determined and ranged from approximately 6150 feet (1875 meters) to approximately 7050 feet (2149 meters) and through valley (and wind gap) depths were also calculated and ranged from approximately 30 feet (9 meters) to about 290 feet (88 meters). Map evidence suggesting these through valleys (and wind gaps) originated as components of diverging and converging complexes of bedrock-walled channels is described and suggests large and prolonged southeast-oriented floods once flowed from or across the Spearfish Creek drainage basin to the Rapid Creek drainage basin. Based on today’s topography there is no upland Black Hills region capable of generating the large and prolonged floods required to erode the observed through valleys (and wind gaps) and their associated diverging and converging channel complexes so the erosion is interpreted to have taken place while the Black Hills were just beginning to emerge as the topographic high they are today. A water source could not be determined from map evidence, but large and prolonged southeast-oriented floods across the region are consistent with a recently proposed hypothesis that massive southeast-oriented (continental ice sheet) ice-marginal melt water floods eroded what are today western South Dakota and North Dakota river drainage basins. 

Effects of anisotropic transmissivity on a contaminant plume at Nemo, South Dakota

2002 ◽  
Vol 8 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Perry H. Rahn ◽  
Christopher S. Johnson
Keyword(s):  
South Dakota ◽  
Ground Water ◽  
Contaminant Plume ◽  
Domestic Water ◽  
Monitoring Wells ◽  
Water Wells ◽  
Low Concentrations ◽  
High Concentrations ◽  
Equipotential Map ◽  
Anisotropic Transmissivity

Abstract In 1996 low concentrations of ethylene dibromide (EDB) were found in thirteen domestic water wells in Precambrian metamorphic rocks at Nemo, South Dakota. The source of the contaminant is believed to be the result of pesticides disposed at a U.S. Forest Service Work Station area in the 1970s. Monitoring wells were installed and ground water from nine of them contained EDB. Sixteen additional wells within three kilometers of Nemo were sampled but EDB was not detected. Water in two domestic wells one kilometer south-southeast of Nemo had high concentrations, 13 and 2.2 micrograms per liter of EDB. The impacted landowners were initially provided bottled water by the USFS. The USFS then drilled new wells outside of the contaminant plume which now provide water to the impacted landowners. An equipotential map indicates that ground water should flow easterly. However the contaminant plume extends towards the south-southeast, in the direction as the foliation in the Precambrian phyllite and quartzite at Nemo. This foliation strongly influences the direction of contaminant migration. Based on an equipotential map and the known plume orientation, a graphical solution of the transmissivity anisotropy indicates that the major transmissivity is oriented N 10 degrees W and is approximately 0.73 m 2 /d. The minor transmissivity is 0.13 m 2 /d. A computer solution utilizing anisotropic transmissivity generated a plume which agrees with the field data.

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