National Geographic : 1972 Jan
east of the lake except the park and three water-conservation areas, where rainfall is stored during the wet season (maps, pages 4 5). The conservation areas, incidentally, are open for hunting; two admit fishermen and controversial swamp buggies and airboats that leave damaging scars (preceding page). Secretary Reed has strong feelings con cerning deer hunting in the Everglades. "I do not approve of running an animal down with a swamp buggy and shooting it," he told me. "I believe that large portions of Conservation Area Three should be off limits and kept in a wilderness state. Surely you can improve on a situation where you have five and six vehicles racing around with dogs howling and men screaming and yelling, climaxed by shooting down an 80-pound animal. Itborders on the Romans and the lions." Salt Water Threatens Miami Supply I drove from Big Cypress to Miami to find out how the water-management system has worked under pressure of drought. Garrett Sloan, Director of the City of Miami's Depart ment of Water and Sewers, looked worried. As we examined a geological cross-section map, Mr. Sloan pointed to a large gray area. "The Biscayne aquifer is this porous rock substructure running down to about 110 feet below ground level. It has always been charged by local rains, and by water from the three conservation areas. Now they are dry. For the first time in history we are bringing water more than 70 miles directly from Lake Okeechobee through drainage canals to re charge our well fields. We have 29 wells strad dling the Miami Canal. By keeping that canal full, we are able to continue pumping. "If we fail to recharge the aquifer, we get salt-water encroachment. The salt water comes in because it's heavier than fresh water. We have to keep our canals two feet higher than sea level to hold it out [diagrams, page 25]. During this drought, salt water began coming in. We cannot remove salt in our treat ment plants. We recently shut down eight wells because of high salt levels. Throughout this century, area communities repeatedly have had to move their well fields west, away from the ocean, in order to have fresh water." I knew that Miami's water system pumped about 150 million gallons of fresh water a day. About 50 million gallons literally went down the drain daily to carry sewage to a plant at Virginia Key, between Miami Beach and Key Biscayne. "After neutralizing three-fourths of the harmful elements, the waste is discharged less than a mile offshore in 18 feet of water," Mr. Sloan said. "Except for Miami and Holly wood, the other south Florida areas draining sewage into the sea are dumping it raw." Many people are concerned about the loss of 50 million gallons a day of fresh water to the sea, when it might be processed and either A land loses its lifeblood. Seeking the water table at a monitoring station (left), Jon Hergert of the United States Geological Survey finds not a drop in sight. Normally this soil lies under two feet of water. Zero mark on the staff gauge in the bottom of the hole is at sea level. Later Mr. Hergert blasted a new hole and finally found water more than a foot below sea level. Mosaic of marl, dried and cracked, paves an area near the Shark Valley Loop Road in Everglades park (right). Deposited by a community of organ isms called periphyton, marl is 95 percent calcium carbonate and piles up one to three inches thick in areas under shallow water. In the fore ground lies the shell of an apple snail, the exclusive diet of the endangered Everglade kite.