EVERGLADES (FLORIDA)

The Everglades are extensive marshlands in southern Florida. They originally extended about 100 miles (160 kilometers) from Lake Okeechobee south to the Gulf of Mexico. More than 40 miles (64 kilometers) wide in some sections, they have an area of 4,000 square miles (10,360 square kilometers). The northern part of the Everglades has been drained by a complex system of canals and dikes, and its rich soils are now used for farming. The southern part has been preserved as the 2,188 square mile (1,400,533-acre) Everglades National Park, which was established in 1947. The Everglades were formed in a flat, shallow basin with a limestone floor that slopes very gradually to the Gulf of Mexico. The area receives over 55 inches (140 centimeters) of rain annually. Water accumulates on the surface because the porous limestone floor has been sealed by peat deposits formed by decomposing vegetation. Evaporation and drainage to the Gulf of Mexico regulate the water level. The Everglades support a unique pattern of vegetation characterized by plains of saw grass and thick hummocks of pine, cypress, and mangrove trees. The mangrove may grow as high as 70-80 feet (21-24 meters). A unique ecological system, the Everglades are under threat from 100 years of dredging, draining, and land clearing. The flow of water across the area and into the Biscayne Aquifer has been drastically reduced; seawater has intruded into the aquifer; and fertilizer runoff has encouraged the growth of algae and of non-indigenous flora. A major rescue effort has begun, involving primarily the restoration of natural water courses throughout the Everglades based on early channelization efforts of the U.S. Army Corps of Engineers (COE).