The Sparta-Memphis aquifer is a major source of industrial and public water supplies as well as a source of water for agricultural purposes in eastern and south-central Arkansas. The potentiometric-surface map for this aquifer, compiled from wastewater level measurements made during spring 1986, indicates a generally eastward and southward hydraulic gradient. The potentiometric surface also shows three major cones of depression resulting from groundwater withdrawals for industrial and public supplies; one centered in Columbia County, one in Union County, and one in Jefferson County. The water level change maps for the Sparta-Memphis aquifer for the period between spring 1981 and spring 1986 show large areas of both rise and decline in water levels across the study area. Largest rises occurred in parts of Jefferson, Columbia, and Phillips Counties, whereas largest declines occurred in parts of Union County. (USGS)