Potentiometric Surface Mapping of the Arikaree Aquifer, Pine Ridge Indian Reservation and Bennett County, South Dakota

Science Center Objects

Project Period: 1998-2007
Cooperator: Oglala Sioux Tribe
Project Chief: Janet Carter

Executive Summary

The Pine Ridge Indian Reservation and Bennett County are located in south-central South Dakota. The Pine Ridge Indian Reservation includes all of Shannon County and the portion of Jackson County south of the White River. Extensive trust lands are in Bennett County. For purposes of this study, all of Bennett County is included in the study area.

Ground water from wells and springs is the predominant source of public and domestic supply within the study area. The Arikaree aquifer is the largest source of ground water throughout this area. The Oglala Sioux Tribe (OST) has developed a ground-water management plan designed to “preserve, protect and maintain the quality of ground water for living and future members and non-members of the Oglala Sioux Indian Tribe within the internal and external boundaries of the Pine Ridge Reservation.”  Hydrologic information about the Arikaree aquifer is important to managing this resource.

In 1998, the U.S. Geological Survey (USGS) began working in cooperation with the Oglala Sioux Tribe to develop a potentiometric map of the Arikaree aquifer in Jackson and Shannon Counties, with a primary component of that effort in conducting a well inventory in those counties. In 2003, the study area was expanded to include Bennett County.

Objective

The objective of this study was to prepare a potentiometric surface map of the Arikaree aquifer for the Pine Ridge Indian Reservation and Bennett County. The map provides a tool for estimating depth to water table for many parts of the study area and also for evaluating ground-water flow directions and hydraulic gradients in the Arikaree aquifer. The water-level and spring data used in constructing the map also are included as a data set of the final map.