The surficial aquifer at the U.S. Naval Station near Mayport, Florida

The surficial aquifer at the U.S. Naval Station near Mayport, Florida, consists of about 70 feet of unconsolidated sand, shell , and clay. The principal water-bearing zone is a shell bed 35 to 55 feet below land surface. The aquifer is unconfined, and the water table was about 4 feet below land surface during the investigation (spring 1979). Aquifer tests indicate a transmissivity for the aquifer of approximately 2,400 feet squared per day. Water in the upper 40 feet of the aquifer is fresh, but becomes increasingly brackish with depth. Use of water from the surficial aquifer is limited because of low yields and poor water quality. Feasibility of injection of return cooling water into the surficial aquifer is limited by the shallow water table.