Fresh groundwater in the Cape Lookout National Seashore in North Carolina occurs in the unconfined aquifer, an upper confined aquifer, and a lower limestome aquifer. The unconfined aquifer beneath dunes on the barrier islands is estimated to yield as much as 30 gallons per minute of freshwater to a horizontal well, but this aquifer is subject to periodic overwash by the ocean, thus temporarily contaminating the aquifer with saltwater. The upper confined aquifer is about 90 to 150 feet deep, but is known to contain freshwater only in the Drum Inlet area. The potential yield of this aquifer where it is fresh is unknown because of the possibility of saltwater encroachment. The lower limestone aquifer (150 to 550 feet deep) contains freshwater southeast of Drum Inlet; potential yields is estimated to be as great as 500 gallons per minute per well. The estimated yields from all aquifers depend on the position of the saltwater interface at any given site. Maps of the Seashore show areas where freshwater may occur in the unconfined aquifer; each map is accompanied by a description of the availability of freshwater.
Additional publication details
USGS Numbered Series
Ground-water resources of the Cape Lookout National Seashore, North Carolina