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Confined wells and artesian conditions in the regional aquifer occur near the center of the basin. In the case of Saint David Springs, 6 miles south of the town of St David, fine-grained beds restrict vertical groundwater movement. There are two areas where confined conditions are found:
Shallow wells drilled deeper than 100 feet in or near the San Pedro River south of Saint David encounter artesian conditions. Artesian wells that flow water above the surface are known as “flowing artesian wells. Many artesian wells flow above the surface and others rise near the surface. Those that rise near the surface are artesian but not flowing artesian. Deep wells of 800 feet depth puncture the clay lens originating at the Dragoon mountains. These wells lift water to near or above the surface due to the hydraulic pressure of an enormous lake that lies below the lens.
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