Helping to blockade saltwater intrusion are coastal gates installed on South Florida's major flood control canals. They carry fresh water from the west to the coast and hold it there to saturate the aquifer and boost groundwater levels. But some coastal wells lie east of those canal salinity barriers. To cope with saltwater intrusion, coastal cities have drilled new wells farther inland. They have pumped those harder and relied less on their eastern wells, usually tapping them only in wet periods.
Some towns put their endangered wells on standby.
But coastal towns are reluctant to abandon coastal wells altogether. The water that bleeds into them has moved much farther through geological filters, including fine-grained sand, and is clearer than water in western wells, he said. Western water is darker, more tea-colored, from soaking through Everglades muck and organic matter. It costs more to clean because there is more color to strip out. Wells closer to the coast are more productive, too, because their aquifer rock can absorb and transmit more water with less pumping.