Saltwater Intrusion in the Floridan Aquifer System, Northeastern Florida
Spechler, Rick M.
Phelps, G. G.
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Saltwater intrusion is a potential threat to the quality of ground water in northeastern Florida and southeastern Georgia. Elevated chloride concentrations have been observed in wells tapping the Upper Floridan and the upper zone of the Lower Floridan aquifers. In Duval County, Florida, increased chloride concentrations in water from wells along the coast and up to 14 miles inland indicate that saline water is gradually intruding into the freshwater zones of the Floridan aquifer system. Several mechanisms may explain this intrusion of saline water and the consequent increase in concentrations of chloride in northeastern Florida. The most plausible explanation for the movement of higher chloride water into the freshwater zones of the Floridan aquifer system is the upward movement of saline water along joints, fractures, collapse features, faults, or other structural anomalies. These features create conduits of relatively high vertical conductivity, providing a hydraulic connection between freshwater zones and deeper, more saline zones. After saline water reaches the freshwater zones, it can then move laterally through the porous aquifer matrix or along horizontal fractures or solution zones.