Digitized Contours from Georeferenced Plate 1975 from "Potentiometric maps of the Sparta Sand, northern Louisiana and southern Arkansas, 1900, 1965, 1975, and 1980" (Ryals, 1980; version 1.1, April 2021)

The potentiometric surface of the Sparta Sand in northern Louisiana is shown by contours on four maps. Maps for 1900, 1965 , and spring 1975 are generalized, small-scale maps from previously published reports. The spring 1980 map (1:500,000) is based on measurements in 144 wells and includes the southern tier of counties in southern Arkansas. The map shows regional effects of pumping from the Sparta Sand and effects of local pumping centers at Magnolia and El Dorado, Ark., and at Minden, Ruston, Jonesboro-Hodge, Winnfield, Bastrop, and in the Monroe area of Louisiana. (USGS) First release: April, 2019; revised April 2021 (version 1.1). The previous version can be obtained by contacting the USGS Lower Mississippi-Gulf Water Science [...]