Louisiana ground-water map no. 8; potentiometric surface, 1991, of the Carrizo-Wilcox Aquifer in northwestern Louisiana

In northwestern Louisiana, the Carrizo-Wilcox aquifer is the primary source of ground water within six parishes (Bossier, Caddo, De Soto, Natchitoches, Red River, and Sabine) and the secondary source in parts of three other parishes (Bienville, Claiborne, and Webster). Withdrawals from the aquifer increased from 4.7 Mgal/d (million gallons per day) in 1965 to 13.3 Mgal/d in 1990. A map of the potentiometric surface indicates that the altitudes of water levels in the Carrizo-Wilcox aquifer ranged from less than 100 feet to 300 feet above sea level in November and December 1991. The direction of ground-water flow within the aquifer generally is to the southeast and east or west to the Red River Valley.