Introduction

The urban and agricultural corridor of southeastern Florida generally lies between the Everglades and water-conservation areas to the west and the Atlantic Ocean to the east but includes the Everglades Agricultural Area south of Lake Okeechobee (fig. 1). The area in eastern Miami-Dade, Broward, and Palm Beach Counties is subject to widely opposing stresses on the environment. A highly controlled water-management system evolved during the 20th century to provide drained land for a rapidly expanding population. Drainage of Everglades wetland areas during the last 75 years has provided continuous opportunity for the westward expansion of agricultural, mining, and urban activities. The population of southeastern Florida increased from about 3,500 inhabitants in 1900 to about 5 million in 2000 (fig. 2). The tri-county area under cultivation expanded from about 223,000 acres in 1953 to more than 590,000 acres in 1988, but declined to about 535,000 acres by 1995.

Figure 1. Location of the urban-agricultural corridor of southeastern Florida. The April 1999 map image modified from Earth Satellite Corporation (2004). [larger image]

Surface water is impounded in water-conservation areas that lie west of a protective levee system, partly to: sustain an Everglades ecosystem, keep overland sheetflow from moving eastward and flooding urban and agricultural areas, and use for urban and agricultural water supply. In coastal areas of the urban-agricultural corridor, parallel environmental conflicts exist. Coastal residential and urban areas must be drained for flood control; the underlying surficial aquifer system simultaneously serves as the principal source of water supply, and ground-water levels must be maintained to prevent coastal saltwater intrusion. Ground-water flow patterns have been altered, and a reduction in ground-water discharge to coastal bays has modified shallow marine salinity and affected the local ecology.

Figure 2. Population growth in southeastern Florida, 1900 to 2000. Compiled from files of the U.S. Bureau of the Census (2004). [larger image]

Rapid urban development and population growth have placed extraordinary demands on the coastal environment in southeastern Florida. Changes in the coastal hydrology of the surficial aquifer system in the region are the direct consequences of water-management practices and concurrent agricultural and urban development. The U.S. Geological Survey (USGS), as part of its Greater Everglades Priority Ecosystems Science Program, conducted a study to: (1) assess the hydrologic character of the surficial aquifer system, (2) review the impact of water-management controls on the ground-water system, and (3) examine the manner in which urban and agricultural areas have affected the ambient quality of ground water.