Delineation of saltwater intrusion in the Biscayne aquifer, eastern Broward County, Florida, 1990

Chloride concentrations in water samples from 63 saltwater monitoring wells in eastern Broward County were used to delineate the areal extent of 1,000 milligrams per liter of chloride concentration from the Biscayne aquifer. The 1990 landward extent of saltwater intrusion and data for 1980 and 1990 for each monitoring well are presented. The results of the study indicate that chloride concentrations in ground water east of major well fields have increased and that the saltwater-freshwater interface has moved landward from 1980 to 1990 in response to lowered regional water levels. This lowering of water levels is the result of the construction of tidal canals and the withdrawal of water from well fields. Historical data from three monitoring wells (G-1237, G-1435, and G-20555) were analyzed to determine trends in chloride concen- tration as a function of time. Samples from wells G-1435 and G-2055 indicate that the chloride concentrations have increased steadily with declines of regional water levels, whereas data from well G-1237 indicate that a decrease in pumpage can reverse saltwater intrusion.