The restoration of the Everglades is an ongoing effort to remedy damage inflicted on the environment of southern Florida during the 20th century. It is the most expensive and comprehensive environmental repair attempt in history. The degradation of the Everglades became an issue in the United States in the early 1970s after a proposal to construct a jetport in the Big Cypress Swamp. Studies indicated the airport would have destroyed the ecosystem in South Florida and Everglades National Park. After decades of destructive practices, both state and federal agencies are looking for ways to balance the needs of the natural environment in South Florida with urban and agricultural centers that have recently and rapidly grown in and near the Everglades.
In response to floods caused by hurricanes in 1947, the Central and Southern Florida Flood Control Project (C&SF) was established to construct flood control devices in the Everglades. The C&SF built 1,400 miles (2,300 km) of canals and levees between the 1950s and 1971 throughout South Florida. Their last venture was the C-38 canal, which straightened the Kissimmee River and caused catastrophic damage to animal habitats, adversely affecting water quality in the region. The canal became the first C&SF project to revert when the 22-mile (35 km) canal began to be backfilled, or refilled with the material excavated from it, in the 1980s.
When high levels of phosphorus and mercury were discovered in the waterways in 1986, water quality became a focus for water management agencies. Costly and lengthy court battles were waged between various government entities to determine who was responsible for monitoring and enforcing water quality standards. Governor Lawton Chiles proposed a bill that determined which agencies would have that responsibility, and set deadlines for pollutant levels to decrease in water. Initially the bill was criticized by conservation groups for not being strict enough on polluters, but the Everglades Forever Act was passed in 1994. Since then, the South Florida Water Management District (SFWMD) and the U.S. Army Corps of Engineers have surpassed expectations for achieving lower phosphorus levels.