The Mississippi River Valley alluvial aquifer in Mississippi

The Mississippi River valley alluvial aquifer, of Quaternary age , contains freshwater in an area of 7,000 sq mi adjacent to the Mississippi River in northwestern Mississippi, and in a 500 sq mi irregular area in southwestern Mississippi. It is the highest yielding aquifer in Mississippi with individual well yields as high as 5,000 gal/min. Major wells producing from the aquifer range in depth from 60 to 260 ft and are commonly screened in the coarse gravel at the base of the aquifer. Water levels in wells are generally between 5 and 30 feet below land surface, except near points of heavy pumping. Water from the alluvial aquifer is a hard, calcium bicarbonate type containing excessive iron in most places. In 1975, 745 Mgal/d, mostly for irrigation, were withdrawn from the alluvial aquifer. In the 7,000 sq mi area in northwestern Mississippi, the alluvial aquifer has been estimated to be capable of yielding over 1,700 Mgal/d, not including the 500 sq mi area in southwestern Mississippi. (Woodard-USGS)