The surficial aquifer is the primary source of freshwater for the heavily developed coastal area in eastern Palm Beach County, Florida. Well fields are generally located in a discontinuous zone of higher secondary permeability, the northernmost extension of the Biscayne aquifer in the surficial aquifer, that extends from the Juno Beach area south to Broward County and varies in width from about 4 to 15 miles. The zone was formed by varying dissolution of aquifer limestone materials during Pleistocene age changes in sea level, and ranges in depth from about sea level to 220 feet below sea level. Because of proximity to the Atlantic Ocean and saltwater estuaries, the aquifer is susceptible to saltwater intrusion. Ground water to the west of the zone of higher secondary permeability is of poor quality. The ground water is calcium bicarbonate dominant. Dissolved solids, calcium carbonate hardness, and chloride are greatest along the saltwater intruded coastline and in the western part of the study area where diluted residual seawater exists. Total organic carbon increases inland due to infiltration of rainwater through thicker layers of organic soils. Ground-water levels in the surficial aquifer in eastern Palm Beach County are strongly influenced by controlled levels in canals. In March 1981, after 12 months of below average rainfall, ground-water levels ranged from about 2 feet above sea level along the coast to nearly 21 feet above sea level 15 miles inland in the northwest section of the study area. (USGS)
