Status of water levels in aquifers in the Nacatoch sand and Tokio Formation of southwestern Arkansas, 1996

Aquifers in the Nacatoch Sand and Tokio Formation in southwestern Arkansas are a source of water for industrial, public supply, domestic, and agricultural uses.Water-level measurements were made in 24 wells completed in the Nacatoch Sand and 18 wells completed in the Tokio Formation from August through October 1996 to produce potentiometric-surface maps.The direction of ground-water flow in aquifers in the Nacatoch Sand and Tokio Formation generally is to the south-southeast or southeast.Potentiometric highs for both aquifers are in the outcrop areas.The aquifer in the Tokio Formation has artesian flow in southeastern Pike, northeastern Hempstead, and northwestern Nevada Counties.One apparent cone of depression was evident within the study area in the aquifer in the Nacatoch Sand.Withdrawals from aquifers in the Nacatoch Sand and Tokio Formation increased from 1965 to 1980 and decreased from 1980 to 1995.Long-term hydrographs were prepared for seven wells in the study area.Changes in water levels in three wells completed in the aquifer in the Nacatoch Sand and one well completed in the aquifer in the Tokio Formation might be associated with decreased withdrawals.Evidence of an association between withdrawals and water levels in three wells is not apparent.l]n this report, sea level refers to the National Geodetic Vertical Datum of 1992 a geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called Sea Level Datum of 1929