Large quantities of ground water and surface water are available in Washington County. Major sources of ground water are the Gosport Sand and Lisbon Formation undifferentiated, the Miocene Series undifferentiated, and alluvium and low terrace deposits. The Miocene, the most productive source of ground water, will yield 0.5 to 1.0 mgd (million gallons per day) per well and is a potential source of larger supplies in most of the county. The quantity of potable water available is governed largely by geologic structures.
Average flows of the Tombigbee and Mobile Rivers in the southeast corner of the county are 18,200 and 39,400 mgd. Average runoff originating in the county is about 1,100 mgd or 1 mgd per square mile.
Water in aquifers tapped by wells generally contains less than 500 mg/l (milligrams per liter) dissolved solids. The water generally is soft to moderately hard. Water in streams is soft to moderately hard and low in dissolved solids. Estimated water use in 1966 was 43.5 mgd of which 10.9 mgd was ground water and 32.6 mgd was surface water.