Lowering the natural water levels has had by far the greatest initial impact on the integrity of the vast expanses of wetlands of the Everglades region. Early drainage efforts sought to reduce water levels for agriculture in marsh and swamplands, and secondarily to provide for navigation. There was little regard for conserving water for irrigation and potable uses as fresh water was thought to be inexhaustible. Flood control efforts focused on directing interior waters through canals to coastal tidal waters as quickly as feasible. Canals from Lake Okeechobee were constructed through the Everglades to the Atlantic Ocean, which not only lowered Lake Okeechobee and partially drained the Everglades, but also interrupted the original flow pattern of the Everglades. Within a few decades, uncontrolled drainage brought many problems. In dry years, most notably during an intense drought in 1944–1945, many water supply wells were ruined by saltwater intrusion into former freshwater aquifers. Drying of the peat soils caused subsidence of 1–5 feet over large areas and fostered uncontrollable soil fires with their attendant, choking smoke. Alternatively, the system had insufficient capacity to prevent flooding in very wet years such as 1947.
It was the excessive flooding in 1947 that convinced Congress to act on plans that had been developing but awaited such an emergency. In 1948, the Central and Southern Florida Project for Flood Control and Other Purposes (C&SF Project) was authorized. Changing flood control to water management, the C&SF Project was comprehensive, addressing flooding, water supply, saltwater intrusion, agricultural expansion, and land development for residential, commercial, and industrial uses of urban landscapes. It also sought to protect the remaining Everglades, as understood from the engineering perspective of “contain and control.” Implementation began in the early 1950s and was essentially complete by 1973.