Abstract

This area is one of the most productive artesian areas in the United States. The wells yield, by flow or pumping, at least 180 million gallons a day, of which six industrial plants use more than 80 million gallons a day; the remainder is used for many different industrial, public, and domestic supplies, or is discharged from flowing wells without being used.The Eocene Ocala limestone is the principal water-bearing formation, and lies at depths of about 200 to 500 feet. Everywhere within about 25 to 30 miles of the coast, the wells that end in the Ocala limestone will overflow at the surface, except in a few small local areas, and in and near Savannah, where all wells have ceased to flow because of the large withdrawal of water.The piezometric surface is at present similar to the original piezometric surface except that its coastward slope has been steepened and large cones of depression have developed on it around Savannah and Fernandina by the large withdrawals of water.Field tests indicate that in the vicinity of Savannah the coefficient of transmissibility of the water-bearing limestone is about 230,000; around Fernandina, Fla., it is less. The shape of the piezometric surface, together with information on the quantity of water taken from wells, indicates that in the vicinity of Brunswick, Ga., and Jacksonville, Fla., the coefficients of transmissibility are much larger than that at Savannah and Fernandina.The total dissolved solids in Ocala water ranged from less than 175 to about 500 p.p.m.Although the Ocala limestone contains salt water in the region north and south of the coastal area of Georgia and northeastern Florida, samples of water from the Ocala within the area show no evidence of encroachment of salt water. However, in localities such as Savannah, where large withdrawal of water has formed a large cone in the piezometric surface, encroachment will occur if that cone extends to an area where salt water is present in the formation.

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