Saltwater contamination at Brunswick is the result of upward intrusion of saline water from the lower part of the Fernandina permeable zone into freshwater zones of the Lower Floridan, then Upper Floridan aquifers. Saltwater from the Fernandina permeable zone migrates upward through fractures and conduits in the limestone and dolostone confining units in response to reduced artesian pressure caused by pumping of water from the Upper Floridan aquifer. Upon reaching the aquifers in the southern part of Brunswick, the saltwater moves toward areas of ground-water pumping in the northern part of Brunswick.

Contamination of the Upper Floridan aquifer in the Brunswick area is not due to lateral encroachment nor downward intrusion of seawater because the Upper Floridan aquifer is deeply buried at Brunswick (greater than 500 feet deep); the freshwater-saltwater interface is far from the coastline (more than 50 miles offshore); and perhaps most importantly, pressure in the Upper Floridan aquifer was greater than sea level when saltwater contamination at Brunswick was first detected in the late 1950’s. Lateral encroachment or vertical infiltration of saltwater may be possible, however, in the shallower surficial aquifer or in the upper and lower Brunswick aquifers.

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Surface-water contamination publication links:

• Saltwater Contamination in the Upper Floridan Aquifer at Brunswick, Ga.
• Hydrogeology and water quality of the Lower Floridan aquifer, coastal Georgia
• Saltwater contamination of ground water at Brunswick, Georgia and Hilton Head Island, South Carolina
• Preliminary Models of Saltwater Transport in Coastal Georgia and Southeastern South Carolina