Potentiometric contours for the Nacatoch aquifer of Northeastern and Southwestern Arkansas and the Tokio aquifer of Southwestern Arkansas, 201415

The Nacatoch Sand in northeastern and southwestern Arkansas and the Tokio Formation in southwestern Arkansas are sources of groundwater for agricultural, domestic, industrial, and public use. Water-level altitudes measured in 51 wells completed in the Nacatoch Sand and 42 wells completed in the Tokio Formation during 2014 and 2015 were used to compile potentiometric-surface maps of the two areas. Aquifers in the Nacatoch Sand and Tokio Formation are hereafter referred to as the Nacatoch aquifer and the Tokio aquifer, respectively. Potentiometric surfaces show that groundwater in the Nacatoch aquifer flows southeast toward the Mississippi River in northeastern Arkansas. Groundwater flow direction is towards the south and southeast in Hempstead, Little River, and Nevada Counties in southwestern Arkansas. A possible cone of depression may exist in southern Clark County and likely alters groundwater flow from a regional direction toward the depression. In southwestern Arkansas, potentiometric surfaces indicate that groundwater flow in the Tokio aquifer is towards the city of Hope. Northwest of the city of Hope, a cone of depression may exist. In southwestern Pike, northwestern Nevada, and northeastern Hempstead Counties, an area of artesian flow (water levels are at or above land surface) exists.