Changes in saltwater intrusion in the Biscayne aquifer, Hialeah-Miami Springs area, Dade County, Florida

A lobe of salty groundwater that had intruded the Hialeah-Miami Springs area municipal well field, adjacent to the Miami and Tamiami Canals in Dade County, Florida, was stabilized after flow-regulation structures were installed in the canals in 1946. However, in 1971, the saltwater began to readvance toward the center of the well field because of water level declines caused by large increases in withdrawals during a near-record dry season. To better protect the well field, a temporary flow-regulation structure, constructed in 1971, in the Tamiami Canal was moved in 1976 to a permanent site, about 3,000 ft farther seaward; this converted that tidal reach of canal to a controlled reach under a sustained freshwater head. This water management procedure resulted in dilution of the intruding saltwater lobe and a marked concentration of its size even though large municipal withdrawals continued. (USGS)