Water table in the surficial aquifer and potentiometric surface of the Floridan Aquifer in selected well fields, west-central Florida, May 1978

The water table in the surficial aquifer and the potentiometric surface of the Floridan aquifer in a 1,200-square-mile area in west-central Florida are mapped semiannually by the U.S. Geological Survey. Maps are prepared showing water levels measured in wells each May to coincide with seasonal low levels, and each September to coincide with seasonal high levels.

The mapped area shows 11 well fields which supplied 144.0 million gallons to municipalities on May 16, 1978. The water is withdrawn from the Floridan aquifer, the major aquifer in Florida. The effect of localized withdrawal of ground water is shown on the maps as depressions in both the potentiometric and water-table surfaces.

Water levels were generally lower in May 1978 than in September 1977 because of seasonal rainfall. The maximum decrease determined was more than 17 feet at Sun City well field. Water levels in May 1978 were generally higher than in May 1977 because of heavy rainfall in early May. However, water levels in well fields with significant increases in pumpage were lower.