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Florida's Water Issues: Saltwater Intrusion

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Florida's Water Issues - Saltwater Intrusion Saltwater intrusion leading to contaminated drinking water wells has long been feared in South Florida. Saltwater intrusion occurs naturally to some degree in most coastal aquifers, owing to the hydraulic connection between groundwater and seawater. Because saltwater has a higher mineral content than freshwater, it is denser and has a higher water pressure. There are three primary mechanisms by which saltwater contaminates the freshwater reservoir in the unconfined, surficial aquifers of the region: one, subsurface movement of seawater (lateral large-scale intrusion), two, seepage of seawater from tidal canals and streams, and three, upward movement of connate saltwater (water remaining from the …show more content…

The canal system is the major factor influencing ground-water levels and the movement of the saltwater interface in southeastern Dade County. The initial canal system, completed in 1967, was designed not only to prevent flooding but also to prevent excessive drainage, allowing for the inland movement of the saltwater interface. Subsequently, the primary changes to the system have been the addition of control structures and pump stations in response to changes in needs for water-level controls. The canals were equipped with flow-regulation structures both near the coast and inland, allowing water levels to be stepped down from structure to structure to prevent excessive drainage. However, the design and operation of this system lowered freshwater levels in the Biscayne aquifer, especially near the coast, allowing for the inland movement of saltwater during the drought years of 1970 and …show more content…

Among these events are the initial operation of the Northwest Well Field and a consequent reduction in pumping from the Hialeah-Miami Springs Well Field, expansion of the Southwest Well Field, and changes in the delivery schedule of water to southern Dade County and Everglades National Park. Chloride concentrations in water samples collected from existing monitoring wells in northeastern Dade County have indicated little, if any, inland movement of the saltwater interface since 1984. The saltwater interface in northeastern Dade County is shown in approximately the same location with differences due to more information being available and not to any perceived movement of the saltwater

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