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STATUS OF WATER LEVELS IN AQUIFERS IN THE NACATOCH SAND OF SOUTHWESTERN AND NORTHEASTERN ARKANSAS AND THE TOKIO FORMATION OF SOUTHWESTERN ARKANSAS, 2002

by T.P. Schrader and Rheannon M. Scheiderer

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Abstract

Aquifers in the Nacatoch Sand and Tokio Formation in southwestern Arkansas and the Nacatoch Sand in northeastern Arkansas are sources of water for industrial, public supply, domestic, and agricultural uses. Potentiometric-surface maps were constructed from water-level measurements made in 60 wells completed in the Nacatoch Sand and 48 wells completed in the Tokio Formation during January and February 2002.

In northeastern Arkansas, withdrawals from the Nacatoch Sand increased by 784 percent from 1965 to 1990 and decreased by 30 percent from 1990 to 2000. In southwestern Arkansas withdrawals from aquifers in the Nacatoch Sand and Tokio Formation increased by 125 percent and 201 percent, respectively, from 1965 to 1980 and decreased by 93 percent and 81 percent, respectively, from 1980 to 2000. Long-term hydrographs were prepared for 13 wells in the study area. Changes in water levels in some wells may be associated with changes in withdrawals from the respective aquifers.

The direction of ground-water flow in the aquifer in the Nacatoch Sand in northeastern Arkansas generally is towards the southeast. The potentiometric high is located along the north and northwestern boundaries of the subarea.

The direction of ground-water flow in the aquifer in the Nacatoch Sand in southwestern Arkansas is towards the south-southeast in Little River, Miller, and Hempstead Counties and to the east-southeast in Nevada and Clark Counties. The potentiometric high is located within the outcrop area in north-central Hempstead County. Cones of depression exist in the aquifer in the Nacatoch Sand in southeastern Hempstead County and in southwestern Clark County.

The direction of ground-water flow in the aquifer in the Tokio Formation in southwestern Arkansas generally is towards the south or southeast. The potentiometric high is located where the aquifer outcrops in the northwestern part of the study area. An area of artesian flow exists in southeastern Pike, northeastern Hempstead, and northwestern Nevada Counties. One apparent cone of depression may exist northwest of Hope in Hempstead County.


TABLE OF CONTENTS

ILLUSTRATIONS
Figure
  1. Map showing location of study subareas
  2. Diagram showing well-numbering system
  3. Graph showing estimated water use by county from the Nacatoch aquifer for the northeastern subarea
  4. Graph showing estimated water use by county from the Nacatoch aquifer for the southwestern subarea
  5. Map showing hydrogeologic setting and potentiometric surface of the Nacatoch aquifer, northeastern Arkansas, January-February 2002
  6. Map showing potentiometric surface of the Nacatoch aquifer, southwestern Arkansas January-February 2002
  7. Water-level altitudes for selected wells completed in the Nacatoch aquifer108. Map showing hydrogeologic setting and potentiometric surface of the Tokio aquifer, southwestern Arkansas, January 2002
  8. Graph showing estimated water use by county from the Tokio aquifer.
  9. Water-level altitudes for selected wells completed in the Tokio aquifer
TABLES
  1. Water-level measurements and well information for wells completed in the Nacatoch aquifer.
  2. Water-level measurements and well information for wells completed in the Tokio aquifer

U.S. Department of the Interior, U.S. Geological Survey
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Last modified: Thursday, September 01 2005, 05:07:33 PM
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