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A Region Under Stress-- Home
A Region Under Stress-- Introduction

Environmental Setting-- The Natural System
Watersheds and Coastal Waters

Environmental Setting-- The Altered System
Drainage and Development
Public Lands
Water Use
Water Budget

Water and Environmental Stress
Loss of Wetlands and Wetland Functions
Soil Subsidence
Degradation of Water Quality
Mercury Contamination
Effects on Estuaries, Bays, and Coral Reefs

Summary and Research Needs

Related Links

Download Circular 1134 PDF

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U.S. Department of the Interior
U.S. Geological Survey
Circular 1134

The South Florida Environment - A Region Under Stress


Regional ecosystem and watersheds in the study unit boundary
Figure 1. Regional ecosystem and watersheds in the study unit boundary, south Florida. Click on image to open larger picture (25.1k).

At the time of settlement by Europeans (mid-1800's), the south Florida region was a lush, subtropical wilderness of pine forest, hardwood hammocks, swamps, marshes, estuaries, and bays (Davis, 1943). Wetlands dominated the landscape. The region contained one of the largest wetlands in the continental United States, the Everglades. The Everglades was part of a larger watershed: the Kissimmee- Okeechobee- Everglades that extended for more than half the length of the Florida Peninsula. The Everglades and the Big Cypress Swamp stretched as a continuous wetland across the southern part of the peninsula south of Lake Okeechobee. These wetlands and the entire watershed (fig. 1) provided the freshwater that sustained the high productivity and abundant fisheries of the coastal waters (McIvor and others, 1994).

The wetlands of south Florida were regarded as being inhospitable and without intrinsic value. In the early 1900's, draining the wetlands was considered to be essential for commerce and safety. Loss of lives as a result of hurricane flooding in the 1920's accelerated drainage projects, primarily in the Everglades. Today, much of south Florida's wetlands are intensively managed, with more than 1,400 mi of primary canals and more than 100 water control structures. Because of drainage and development, the south Florida ecosystem has experienced a variety of environmental problems such as loss of soil, nutrient enrichment, contamination by pesticides, mercury buildup in the biota, fragmentation of landscape, loss of wetlands and wetland functions, widespread invasion by exotic species, increased algal blooming in coastal waters, seagrass die off, and declines in fishing resources.

Water is life for the human and natural systems in south Florida. Clean, abundant water was a fundamental characteristic of the original south Florida system. Increased human population and activity in south Florida have brought, not only an increased need for water, but also a decrease in water supply and a deterioration in water quality.Changes in the hydrologic system are thought by many to be the root cause of the dramatic declines in fish and wildlife populations and habitat across the south Florida ecosystem.
Urban and Agricultural Lands in south Florida
Figure 2. Urban and agricultural lands in south Florida. (Modified from South Florida Water Management District and Southwest Florida Water Management District digital data, 1988-90.) Land use and land cover categories based on South Florida Water Management District classification codes. Equivalent categories are shown for the area within the Southwest Florida Water Management District. Click on image to open larger picture (32.5k).
Public Ownership Lands in south Florida
Figure 3. Lands in south Florida under public ownership or control. (Modified from South Florida Water Management District and Southwest Florida Water Management District digital data, 1994.) Click on image to open larger picture (23.7k).

Today in south Florida, competition for water is intense and divided between a large, rapidly growing population along the coast and agriculture north and south of Lake Okeechobee (fig. 2), on the one hand, and the remaining natural ecosystem mostly within State and Federal parks, reserves, sanctuaries, and preserves (fig. 3), on the other. Satisfying the water-resource demands of these competing interests is a complicated and difficult task. The quantity of water required for urban and agricultural uses may, at times, exceed supply. Plants and animals also have critical requirements with respect to the quantity of water, because they are dependent on the timing and duration of wet and dry periods. Water-quality requirements also vary markedly. The Everglades natural biota require water that is extremely low in phosphorus concentration, yet agricultural activities produce waters that contain high levels of phosphorus. Such conditions result in direct competition because the natural biota are "downstream" from the agricultural areas.

Recently, a consensus has begun to emerge among Federal and State agencies and environmental groups that south Florida and the Everglades should be restored, to the extent possible, to patterns similar to those of the original system. For concerned parties to discuss productively, let alone implement, such recommendations requires a substantial increase in available scientific data and understanding of the hydrology, geology, and ecology of south Florida and the Everglades specifically (Holloway, 1994).

The investigations needed to support restoration have been outlined recently by the Science Sub-Group of the South Florida Ecosystem Task Force. These investigations include characterizing the predrainage system and comparing it with the present system, particularly hydrologically; determining the key characteristics of the former natural hydrologic system that supported the rich diversity and abundance of wildlife that has been lost; designing structural and operational modifications of the Central and Southern Florida Project for Flood Control and other Purposes (C&SF) that would recreate the key characteristics of the natural hydrologic system; assessing the hydrologic and ecological results of these modifications through pre- and post- modification monitoring; and modifying the design to make improvements (Science Sub-Group, written commun., 1994).

The U.S. Geological Survey is providing some of the scientific information necessary for protection and restoration in south Florida through several Survey programs that include the South Florida Initiative and the National Water-Quality Assessment (NAWQA) Program. The USGS is coordinating these efforts with other Federal agencies through the South Florida Ecosystem Interagency Working Group and the Science Sub-Group and through regularly scheduled liaison meetings of the Southern Florida NAWQA study unit. The South Florida Initiative is a collaborative effort by the U.S. Geological Survey and other Federal and State agencies to provide scientific insight into conflicting land-use demands and water-supply issues in the south Florida regional ecosystem. The NAWQA Program is described below.
Photo of a fan boat

This report provides an overview of the environmental setting in south Florida and serves as a review and framework for developing USGS programs in the region. In the report, we describe the predevelopment and the current (present-day) environmental conditions in south Florida, with emphasis on the quantity and quality of water. The geographical area covers the southern half of the State, and includes the Southern Florida NAWQA study unit and adjacent coastal waters. The Southern Florida NAWQA study unit covers about 19,500 mi2 and is the watershed of the larger regional ecosystem (fig. 1). We define the regional ecosystem to include coastal waters between Charlotte Harbor on the Gulf of Mexico and the St. Lucie River on the Atlantic Ocean and the lands that drain into these waters (fig. 1).

National Water-Quality Assessment Program

In 1991, the USGS began to implement a full-scale NAWQA Program. The three major objectives of the NAWQA Program are to provide a consistent description of current water-quality conditions for a large part of the Nation's water resources, to define long-term trends (or lack of trends) in water quality, and to identify, describe, and explain the major factors that affect observed water-quality conditions and trends. These objectives are being met (1) by conducting retrospective analyses of existing data, (2) by establishing a long-term nationwide monitoring network designed to assess existing water- quality conditions and provide a data base for trend analyses, and (3) by conducting process-oriented studies designed to provide a better understanding of the relation between land- and water-use activities and water-quality conditions. The NAWQA Program is providing an improved scientific basis for evaluating the effectiveness of water-quality management programs and practices.

The NAWQA Program is being implemented through investigations of hydrologic systems in 60 study units that include parts of most major river basins and aquifer systems in the United States. Study units range in size from 1,200 to about 65,000 mi2 and incorporate 60 to 70 percent of the Nation's water use and population served by public water supply. The south Florida study unit includes most of the southern half of the Florida Peninsula and contains a major urban complex of more than 5 million people. The study unit in this report was included in the NAWQA Program in 1993.


The authors of this report and the U.S. Geological Survey wish to acknowledge the following Survey individuals for their contributions:

David McCulloch, Geographer, who digitized and compiled the Geographic Information System (GIS) that enabled him to generate the maps in this report.

Ronald S. Spencer, Scientific Illustrator, who received the electronically prepared illustrations and prepared them for camera-ready copy.

Twila D. Wilson, Writer-Editor, who created the report's camera-ready design and layout, and performed the editorial and verification review.

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