United States
      Environmental Protection
      Agency
Region 4 Science & Ecosystem
Support Division and Water
Management Division;
Office of Research and Development
EPA904-R-00-003
September 2000
EPA
      South Florida Ecosystem Assessment:
      Everglades Water Management, Soil
      Loss, Eutrophication and Habitat
      Monitoring for Adaptive Management:
      Implications for Ecosystem Restoration

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The South Florida Ecosystem Assessment Project is being conducted by the
United States Environmental Protection Agency Region 4 in partnership with the
Florida International University Southeast Environmental Research Center, FTN
Associates Ltd., and Battelle Marine Sciences Laboratory.  Additional cooperating
agencies include the United States Fish and Wildlife Service, the National Park
Service, the United States Geological Survey, the Florida Department of Environ-
mental Protection, the South Florida Water Management District, and the Florida
Fish and Wildlife Conservation Commission.  The Miccosukee Tribe of Indians of
Florida and the Seminole Tribe of Indians allowed sampling to take place on their
federal reservations within the Everglades.

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                                      EPA 904-R-00-003
                                        September 2000
         SOUTH FLORIDA
ECOSYSTEM ASSESSMENT
        Everglades Water Management,
     Soil Loss, Eutrophication and Habitat
                   Daniel Scheldt
        U.S. Environmental Protection Agency Region 4
              Water Management Division
                 South Florida Office
               West Palm Beach, Florida

              Jerry Stober, Project Manager
        U.S. Environmental Protection Agency Region 4
          Science and Ecosystem Support Division
                  Athens, Georgia

                   Ronald Jones
              Florida International University
         Southeast Environmental Research Center
                   Miami, Florida

                   Kent Thornton
                 FTN Associates, Ltd.
                 Little Rock, Arkansas
      This document is available on the Internet for browsing or download at:
        

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                                             SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
EXECUTIVE   SUMMARY
         The United States Environmental Protection Agency South Florida
      Ecosystem Assessment Project is an innovative, long-term research,
      monitoring and assessment effort.  Its goal is to provide timely scientific
      information that is critical for management decisions on the Everglades
      ecosystem and its restoration. The purpose of this report is to document
      1993 to 1996 baseline conditions in the Everglades and Big Cypress prior to
      ecosystem restoration efforts.  The project is unique to South Florida in two
      aspects: (1) its probability-based sampling approach permits quantitative
      statements about ecosystem health; and (2) its extensive spatial coverage
      and sampling intensity are  unprecedented.

         This  project:

         • contributes to the Comprehensive Everglades Restoration Plan  by
          quantifying pre-restoration conditions in three physiographic regions:
          Everglades  ridge and slough; marl prairie/rocky glades; and Big Cypress
          Swamp.

         • provides information on four groups of Everglades restoration success
          indicators: water column, soils and sediments, vegetation, and fishes.

         • provides a baseline against which future conditions can be compared
          and the effectiveness of restoration efforts can be gauged.

         • assesses the effects and potential risks of multiple environmental
          stresses on the Everglades ecosystem such as water management, soil
          loss, water quality degradation, habitat loss, and mercury contamination.

         • provides unbiased estimates of ecosystem health with known confidence
          limits, while allowing one to differentiate between seasonality and inter-
          annual variability versus the effects of restoration efforts.

         • provides data with multiple applications: updating and calibrating surface
          water management models;  updating models that predict periphyton or
          vegetation changes in  response to phosphorus enrichment or
          phosphorus control; developing empirical  models in order to better
          understand  interrelationships among mercury, sulfur, phosphorus, and
          carbon; developing water quality standards to protect fish and wildlife.

         Samples were collected  from the freshwater portion of the Everglades and
      Big Cypress. From  1993 to 1996 surface water, soil or sediment, periphyton,

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
      and mosquitofish were sampled from about 200 canal locations and over 500
      marsh locations.  These samples represent the ecological condition in over
      750 miles of canals and over 3,000 square miles of freshwater marsh.  A
      second phase of sampling, conducted in 1999 at about 250 marsh locations,
      is summarized in companion reports.

      Key findings:

         • Pronounced water quality gradients:  Water discharged from
          Everglades Agricultural Area canals is loading the public Everglades with
          excess phosphorus, carbon, and sulfur.  Concentrations progressively
          decrease downstream.

         • Canals are a conduit for pollutant transport: The canal system is an
          effective conduit for the transport of degraded water into and through the
          Everglades marsh system. Water management affects water quality.
          Downstream water quality would be improved if delivery canals were
          eliminated or if they were operated  to maximize surface water sheetflow
          and the diluting influence of rainfall  and  cleaner marsh water.

         • Varying water quality: Surface water conductivity, phosphorus, carbon,
          nitrogen, and sulfur vary greatly throughout Big Cypress and the
          Everglades and are dependent upon location, time of year, and water
          management practices.

         • Phosphorus enrichment: As of 1995 to  1996, about  44% of the
          Everglades canal system and 4% of the marsh area had total
          phosphorus concentrations exceeding the 50 part per billion Phase I
          control target.  As phosphorus control programs continue to advance,
          this probability-based sampling can be repeated to determine whether
          the Everglades' condition is improving.

         • So/7 loss in  the public Everglades: From 1946 to 1996, about one-half
          of the peat soil was lost from about 200,000  acres of the public
          Everglades.  Water management must be improved to  maintain the
          remaining marsh soils if the plant communities and wildlife habitat of
          these wetlands are to be preserved.

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                                      SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
   • Marsh habitat a mosaic: Wet prairie and sawgrass marsh were the two
    dominant plant communities in the Everglades, representing 44% and
    47% of the sites sampled.  Water quantity and water quality must be
    managed to maintain these important habitats. Cattail was present at
    10% of these sites, and was associated with elevated soil phosphorus or
    proximity to canals.

   • Periphyton conspicuous: Well-defined periphyton mats, a defining
    characteristic of the Everglades marsh complex, were found at 67% of
    the sample sites.

   • Ecological condition  varies by location and time: The condition of
    the Everglades varied greatly with location.  Rainfall-driven portions of
    the system that are distant from the influence  of canal water, such as the
    interior of Arthur R. Marshall Loxahatchee National Wildlife Refuge and
    the southwest portion of Water Conservation Area 3A, were found to
    have good water quality and low soil phosphorus. The interior of
    Loxahatchee National Wildlife Refuge tended to have the most pristine
    water quality and the lowest phosphorus concentrations  in peat soils.  In
    contrast,  northern Water Conservation Area 3A had poorer water quality,
    soil  loss due to water management, elevated soil phosphorus, and cattail
    encroachment.  Water  Conservation Area 2A had evidence of
    phosphorus enrichment and cattail encroachment, along with high water
    sulfate and conductivity.  Big Cypress had good water quality and no
    obvious indications of phosphorus enrichment. Water quantity conditions
    at a given location vary with season and year.

   • Environmental threats interrelated:  Ecological stressors such as
    water management, soil loss, water quality degradation,  cattail
    expansion, and mercury contamination are often interrelated.
    Management actions must be holistic.

   This project provides a critical benchmark for assessing ecosystem health
and the effectiveness of Everglades restoration activities into the twenty-first
century.  As Everglades protection efforts proceed, this probability-based
sampling can be repeated to document the effectiveness of these  actions.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
ABBREVIATIONS
       cm = centimeter
       cc = cubic centimeter
       cfs = cubic feet per second
       3 = grams
       hr = hour
       ppb = parts per billion (ug/L)
       ppm = parts per million (mg/L) or (mg/ks)
       mg/kg = milligrams per kilogram (ppm)
       mgA = milligrams per liter (ppm)
       ug/cc = micrograms per cubic centimeter
       uMol/hr = micromoles per hour

       AA = Alligator Alley (Interstate 75)
       APA = Alkaline Phosphatase Activity
       APTMD = Air, Pesticides, and Toxics Management Division
       BCNP = Big Cypress National Preserve
       BMPs = Best Management Practices
       CERP = Comprehensive Everglades Restoration Plan
       EAA = Everglades Agricultural Area
       ENP = Everglades National Park
       EMAP = Environmental Monitoring and Assessment Program
       EPA = Everglades Protection Area
       FIU = Florida International University
       LNWR = Arthur R. Marshall Loxahatchee National Wildlife Refuge
       NERL - ERD =  National Exposure Research Laboratory, Ecosystem Research Division. Athens,
          Georgia
       NERL - AMD = National Exposure Research Laboratory, Atmospheric Modeling Division. Research
          Triangle Park, North Carolina
       ORC = Office of Regional Counsel
       SESD = Science and Ecosystem Support Division
       SERC = Southeast Environmental Research Center
       SFWMD = South Florida Water Management District
       TT = Tamiami Trail
       USEPA =  United States Environmental Protection Agency
       WCA = Everglades Water Conservation Area
       WCA3N = Water Conservation Area 3A north of Alligator Alley
       WCA3S = Water Conservation Areas 3A and 3B south of Alligator Alley

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                               SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
US EPA REGION 4
SOUTH FLORIDA
ECOSYSTEM ASSESSMENT
INTRODUCTION AND PURPOSE	1


BACKGROUND 	3


THE COMPREHENSIVE EVERGLADES
RESTORATION PLAN 	7


US EPA REGION 4 SOUTH FLORIDA
ECOSYSTEM ASSESSMENT
PROJECT	10


WATER MANAGEMENT 	16


WATER QUALITY PATTERNS 	18


SOIL SUBSIDENCE	22


EUTROPHICATION AND HABITAT	26


MANAGEMENT IMPLICATIONS 	34


REFERENCES ............................................36

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
ACKNOWLEDGEMENTS

        PARTICIPANTS  IN  THE  US  EPA  REGION  4
        EVERGLADES  ASSESSMENT   PROJECT
        US EPA Region 4
        Program Offices

        APTMD
        L. Anderson-Carnahan
        D. Dubose
        L. Page

        ORC
        P. Mancusi-Ungaro

        SESD
        B. Berrang
        P. Meyer
        C. Halbrook
        M. Parsons
        D. Smith
        W. McDaniel
        M. Wasko
        J. Scifres
        M. Birch
        P. Mann
        I Slagle
        I Stiber
        J. Davee
        D. Colquitt
        D. Kamens
        R. Howes
        G. Collins
        J. Bricker
        B. Noakes
 US EPA - Office of
 Research and Development
 EMAP
 R. Linthurst
 K. Summers
 I Olsen

 NERL-RTP
 R. Stevens
 R. Bullock
 J. Pinto

 NERL-ATHENS
 R. Araujo
 C. Barber
 N. Loux
 L. Burns
FIU-SERC
R. Jaffe
J. Trexler
Y. Cai
A. Alii
N. Black
I. MacFarlane
W. Loftus
J. Thomas
University of Georgia
S. Rathbun
Florida  Department of
Environmental Protection
I Atkeson
 South  Florida Water
 Management District
 L Fink

 Contractors
 J. Maudsley, Mantech
 B. Lewis, Mantech
 M. Weirich, Mantech
 D. Stevens, Mantech
 M. McDowell, Mantech
 C. Laurin, FTN Associates, Ltd.
 J. Benton, FTN Associates, Ltd.
 R. Remington, FTN Associates, Ltd.
 B. Frank, FTN Associates, Ltd.
 S. Ponder, Integrated Laboratory
  Systems
 K. Simmons, Integrated
 Laboratory
  Systems
 S. Pilcher, Integrated Laboratory
  Systems
 E. Crecelius, Battelle Marine
 Sciences
 B. Lasorsa, Battelle Marine
 Sciences
        Funding for this study was provided by the United States Environmental Protection Agency
        Region 4 South Florida Office, West Palm Beach; the Office of Water; the Office of Research and
        Development; and the United States Department of Interior.

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                                                 SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
INTRODUCTION  AND  PURPOSE
         The United States Environmental Protection Agency (USEPA) South Florida Ecosystem
      Assessment Project is an innovative, long-term research, monitoring, and assessment effort.
      Its goal is to provide timely scientific information that is needed for management decisions on
      the Everglades ecosystem and its restoration. The purpose of this report is to document
      1993 to 1996 baseline conditions in the Everglades and Big Cypress prior to ecosystem
      restoration efforts. This project is unique to South Florida in two aspects:

         •  its probability-based sampling approach permits quantitative  statements about
          ecosystem condition; and

         • its extensive spatial coverage is unprecedented.

         The South Florida Ecosystem Assessment Project:

         • contributes to the Comprehensive Everglades Restoration Plan by quantifying
          pre-restoration conditions in three physiographic regions: Everglades ridge and
          slough;  marl prairie/rocky glades; and Big Cypress Swamp.

         • provides information on four groups of Everglades restoration success
          indicators: water column, soil and sediment, vegetation, and fish.
      FIGURE 1 . Numerous environmental issues threaten the Everglades "River of Grass," such as water
      management, soil loss, water quality degradation, and habitat alteration.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
r
      en
GOAL: Provide  timely ecological  information  that contributes to
environmental management decisions on the Everglades and its restoration.
          • provides a baseline against which future conditions can be compared and the
           effectiveness of restoration efforts can be gauged.

          • assesses the effects and potential risks of multiple environmental stresses on
           the Everglades ecosystem such as water management, soil loss, water quality
           degradation, habitat loss, and mercury contamination.

          • provides unbiased estimates of ecosystem health with  known levels of
           uncertainty, while allowing one to differentiate between seasonality and inter-
           annual variability versus the effects of restoration efforts.

          • permits spatial analyses and identifies associations that provide insight into
           relationships among environmental stresses and observed ecological responses.

          • provides data with multiple applications: updating and calibrating surface water
           management models; updating models that predict periphyton or vegetation
           changes in response to phosphorus enrichment or phosphorus control;
           developing empirical models in order to better understand interrelationships
           among mercury, sulfur, carbon, and phosphorus; developing water quality
           standards to protect fish and wildlife.

          USEPA Region 4 and the Florida International University Southeast Environmental
       Research Center began this project in 1993 to monitor the condition of the South
       Florida ecosystem. This project has been carried out in cooperation with the:
       Miccosukee Tribe of Indians of Florida, Seminole Tribe of Indians, United States  Fish
       and Wildlife Service, National Park Service, United States Geological Survey, Florida
       Department of Environmental Protection, Florida Fish and Wildlife Conservation
       Commission, and South Florida Water Management  District.

          This report describes the ecological condition of the Everglades and  Big Cypress
       as documented in the intensive 1993 to 1996 Phase  I sampling effort. A more
       technical presentation of the Phase I sampling can be found in Stober et al., 1998.
       Companion reports summarize the 1999 Phase II project sampling, mercury
       contamination, and the comparative risk assessment. All reports and data for the
       study are available on the internet at .

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                                                  SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
       FIGURE 2. The Everglades wet prairie - sawgrass marsh mosaic.
BACKGROUND
       THE  EVERGLADES
             "Here are no lofty peaks seeking the sky, no mighty glaciers or rushing streams
             wearing away the uplifted land.  Here is land, tranquil in its quiet beauty, serving not
             as a source of water but as a last receiver of it."
             "The Everglades were not really set aside for any kind of geological wonders or
             scenic features.  It's the first national park set aside simply for its wildlife and the
             plants and trees - for its biological diversity."

             President Harry Truman, Everglades National Park dedication, 1947.
          The Florida Everglades is one of the largest freshwater marshes in the world. The
       marsh is a unique mosaic of sawgrass, wet prairies, sloughs, and tree islands. Just
       over 100 years ago, this vast wilderness encompassed over 4,000 square miles,
       extending  100 miles from the shores of Lake Okeechobee south to Florida Bay. The
       intermingling of temperate  and Caribbean flora created habitat for a variety of fauna,
       including Florida panthers, alligators, and  hundreds of thousands of wading birds.
       The Everglades of the past were defined by several major characteristics:

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
          How the water flowed. Water connected the system, from top to bottom.  Surface
       water flowed so slowly down the flat and level landscape that rainfall during one
       season was still available during another. The enormous amount of water storage
       capacity and the slow flow made wetlands and coastal systems less vulnerable to
       South Florida's variable and often intense rainfall'1'.

          Vastness. The large ecosystem area provided a variety of wildlife habitats.
       Millions of acres of wetlands provided large feeding ranges and diverse habitat needs
       for wildlife.  The vastness produced abundant aquatic life while facilitating recovery
       from hurricanes, fires, and other natural disturbances'1'.

          Diverse mosaic of landscapes. The Everglades was a complex system of plant
       and animal life dictated in part by water regime - minimum, average, and maximum
       water depths, along with the duration of surface water inundation.  This resulted in
       expansive areas of sawgrass marshes, wet prairies, cypress swamps, mangrove
       swamps, and coastal lagoons and bays'1'.

          Natural water quality conditions. There were no external sources of pollutants to
       the ecosystem. There was no urban  development or agriculture.  Nutrients, ions,
       and metals all occurred at natural concentrations.  Surface water flowed slowly
       across the landscape, providing ample opportunity for cleansing by extensive
       wetlands. The sawgrass marshes and wet prairies of the Everglades developed
       under extremely low phosphorus conditions.

          The  mosaic of habitats, their vastness and the variety of water patterns supported
       the long-term survival of wildlife under a range of seasonal and annual water
       conditions.

       A TROUBLED RIVER
          One century ago, the greatest threat to wading bird populations was hunting
       (Figure 3).  During the last century, however, the Everglades has become a troubled
       system. In response to periods of drought in the 1930s and 1940s, and severe
       flooding with loss of human  life in the 1920s and 1940s, the Central and Southern
       Florida  Flood Control Project (the Project) was created  in 1948 by federal legislation.
       Project purposes include flood control, water level  control, water conservation,
       prevention of salt water intrusion, and preservation offish  and wildlife.  The Project is
       one of the world's most extensive public water management  systems, consisting of

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                                                    SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
FIGURE 3.  Decorating women's
hats with wading bird plumage led
to the near decimation of
Everglades wading bird populations
around 1900.
over 1,800 miles of levees and
canals, 25 major pumping
stations, and over 200 larger and
2,000 smaller water control gates
or structures.  When the Project
was designed in the 1950s,
about 500,000 people lived in the
region and it was estimated that
there might be two million people
by 2000(1). The Project has
effectively provided flood control
and water supply to facilitate
urban and agricultural growth.
                                Today, 50% of the historic
                             Everglades wetland has been
       drained. The Everglades ecosystem has been altered by
       extensive agricultural and urban development (Figures 4
       to 8). South Florida's human population of about six
       million continues to increase and encroach on the
       ecosystem's land and compete for its water. This human
       population is projected to increase to 15 million within a
       few decades'1' (Figure 4).

           The Everglades changed dramatically during the
       twentieth century as drainage canals were dug to
       facilitate urban and agricultural development. Most of
       the remaining Everglades are in the Everglades
       Protection Area (EPA):  Arthur R. Marshall Loxahatchee
       National Wildlife Refuge (LNWR), Everglades National
       Park (ENP), and the Water Conservation Areas (WCAs)
       (Figure 8).  Everglades National Park, which was
       established in 1947, includes only one-fifth of the
       original "River of Grass" that once spread over more
       than 4,000 square miles (2  million acres)'3'. One-fourth
       of the historic Everglades is now in agricultural
       production within the 1,000 square mile Everglades
       Agricultural Area (EAA), where sugar cane and
                                                                    1900   1930
                                                                                   1990  2020  2050
                                                                FIGURE 4. South Florida population
                                                                from 1900-2050 (projected). Flood control
                                                                provided by the Central and Southern
                                                                Florida Project has made urban expansion
                                                                possible'1-2).
                                   FIGURE 5.  Urban expansion into
                                   drained Everglades wetlands within west
                                   Broward County, 1995.  Note the black peat
                                   soil.
                                   FIGURE 6. Urban expansion into
                                   Everglades wetlands in western Broward
                                   County, 1995.
                                   FIGURE 7. Residential development
                                   on former Everglades wetlands.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT

                                         Lake
                                   Okeechoobee

                            Cypress
                                                                     LNWR
                                                                 WCA2
                                                WCA3N
                                            Alligator Alley (1-75)
                                                WCA3S
                                            Tamiami Trail

           FIGURE 8. Satellite image of South Florida, circa 1995, with the areas sampled outlined in yellow:
           Everglades Agricultural Area (EAA); Arthur R. Marshall Loxahatchee National Wildlife Refuge (LNWR);
           Everglades Water Conservation Area 2 (WCA2); Everglades Water Conservation Area 3 north of
           Alligator Alley (WCA3N); Everglades Water Conservation Area 3 south of Alligator Alley (WCA3S); the
           eastern portion of Big Cypress National Preserve (BCNP), and the freshwater portion of Everglades
           National Park (ENP).  Light areas on the east indicate urban development.

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                                              SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
            During the last century, the Everglades has become subjected to
        multiple, often interrelated, environmental threats.  Effective ecosystem
        protection and restoration requires addressing these threats holistically.
       vegetables are grown on the peat soils of drained sawgrass marshes. Big Cypress
       National Preserve protects forested swamp resources along the western portion of
       the Everglades watershed.

         Although one-third of the 16,000 square mile Everglades watershed is in public
       ownership, there are many environmental issues, often interrelated, that must be
       resolved to restore and protect the Everglades ecosystem. These include: water
       management; water supply conflicts; soil loss; water quality degradation and
       eutrophication; mercury contamination of gamefish, wading birds, and Florida
       panthers; habitat alteration and loss; protection of endangered species; and
       introduction and spread of nuisance exotic species.
THE  COMPREHENSIVE  EVERGLADES
RESTORATION  PLAN
         The Central and Southern Florida Project has provided
       flood protection and water supply to people and agricultural
       lands, as intended. However, the Project has
       simultaneously altered the Everglades and the south
       Florida ecosystem. The Everglades no longer receives the
       proper quality or quantity of water at the right place or the
       right time. The remnant Everglades no longer exhibits the
       water regimes, vast area, and mosaic of habitats that
       defined the pre-drainage natural ecosystem. Wildlife
       habitat has been lost or changed, and the number of
       nesting wading birds (wood stork, great egret, snowy egret,
       tricolored heron, and white ibis) has decreased markedly
       during the twentieth century'4' (Figure  9).  Historically, most
       water slowly flowed across or soaked  into the region's vast
       wetlands.  Today, over one-half of the region's wetlands
FIGURE 9. Everglades
wading bird populations
significantly declined during the
1900s.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
       FIGURE  1 O.  Historic (left) Everglades water flow
       patterns and present flow patterns (right)(adaptedfmm1'5)
FIGURE  11.   An extensive system of
canals, levees, and water control structures has
modified Everglades water conditions and
provides a conduit for pollutant transport. This
pump station discharges untreated stormwater
from an urban basin into the Everglades.
       have been irreversibly drained.  The water storage and water quality filtration
       functions that these wetlands provided is gone.  The canal system quickly drains
       water from developed areas and the wetlands that remain.  On average, a billion
       gallons of fresh water are discharged to the coast each year. Discharges to the
       Everglades are frequently too much or too little,  and are often at the wrong time
       (Figure 10).  Some areas are too wet while other areas are too dry.  Overland
       sheetflow is  interrupted by levees and canals that crisscross the Everglades and
       can provide  a conduit for pollutant transport from urban and  agricultural areas
       (Figure 11).  Nutrient enrichment has become a threat to the Everglades.

          As the human population continues to increase,  urban and agricultural water
       shortages are expected to become more frequent and severe. Conflicts for water
       between natural resources, agriculture, industry, and a growing  population will
       therefore intensify.
       THE  SOLUTION
          Many of the problems with declining ecosystem health revolve around four
       interrelated factors: water quantity, quality, timing, and distribution (Figure 12).
       Consequently, the major goal of restoration is to deliver the right amount of water
       that is clean enough to the right places and at the right time. Since water largely
       defined the natural system, it is expected that the natural system will respond to
       water management improvements (Figure  13).  The Water Resources
       Development Acts of 1992 and 1996 directed the U.S. Army Corps of Engineers to
       review the Project and develop a comprehensive plan to restore and preserve

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                                            SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
FIGURE  1 2. The right water quality,
quantity, timing, and distribution of water
are all critical to South Florida ecosys-
tem protection and restoration'1'.
                                       FIGURE  1 3. The anticipated effect of the Comprehensive
                                       Everglades Restoration Plan (CERP). Without the Plan (left)
                                       restoration targets will not be met (red). With the Plan fully
                                       implemented (right) restoration targets likely will be met (green).
                                       Yellow indicates uncertainty in meeting restoration targets'1'.
south Florida's natural ecosystem, while providing for other water-related needs of
the region including urban and agricultural water supply and flood protection. The
result is the Comprehensive Everglades Restoration Plan (CERP, or the Plan).   The
development of the Plan was led by the Army Corps of Engineers and the South
Florida Water Management District and was accomplished by a team of more than
100 ecologists, hydrologists, engineers and other professionals from over 30 federal,
state, tribal, and local agencies. The Plan includes: about 180,000 acres of surface
water storage areas; about 36,000 acres of man-made wetlands to treat urban or
agricultural runoff; wastewater reuse; extensive aquifer storage and recovery; water
management operational changes; and structural changes to improve how and when
water is delivered to the Everglades, including removal of some of the canals or
levees that prevent natural overland  sheet flow.  The entire Plan is projected to take
over 30 years and cost about $8 billion to  implement, with the cost split equally by
Florida and the federal government.  If nothing is done, the health of the Everglades
will continue to decline, water quality will degrade further, some plant and animal
populations will be stressed further, water shortages for urban and agricultural users
will become more frequent, and the ability to protect people and their property from
flooding will be compromised'1 6).

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
         A series of ecological success criteria have been defined that will gauge the success
      of ecosystem restoration efforts.
            Example Everglades Ecosystem Restoration Success Indicators'7'
    Problem
    Water Management
    Habitat Alteration
    Eutrophication
    Mercury Contamination
    Endangered Species
    Soil Loss
Success Indicators
Reinstate system-wide natural hydropatterns and sheet flow
Increased spatial extent of habitat and wildlife corridors
Reduced phosphorus loading
Reduced top carnivore mercury body burden
Recovery of threatened/endangered species
Restore natural soil formation processes and rates
                   To evaluate restoration success, we must have a
               reliable pre-restoration baseline for ecosystem condition.
USEPA  REGION 4  SOUTH  FLORIDA
ECOSYSTEM  ASSESSMENT  PROJECT
         The attention and funding devoted toward Everglades ecosystem restoration are
      unprecedented. It is imperative that ecosystem health is assessed in a cost-
      effective, quantitative manner such that baseline, pre-restoration conditions are
      documented. Such an assessment identifies resource restoration needs. Continued
      assessment allows one to determine the effectiveness of restoration efforts.  A major
      defining feature of the Everglades is its large spatial area; hence, to monitor
      restoration it is essential to determine the area of the current Everglades that is

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                                         SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
subject to various human impacts. This study employs a scientifically rigorous way of
accomplishing this, using a method called probability-based sampling.

   Assessment information can be used to help answer seven policy-relevant questions:

   1)  Magnitude - What is the magnitude of the problem?  How severe is it?
   2)  Extent- What is the extent of the problem? How large an area is affected?
   3)  Trend - Is the problem getting better, worse, or staying the same?
   4)  Cause - What factors are associated with or causing the problem?
   5)  Source-What are the contributions of and importance of different sources?
   6)  Risk - What are the  risks to different ecological systems?
   7)  Solutions - What management alternatives are available to ameliorate or
      eliminate the problem?

   These seven questions are equally applicable for each  environmental problem
threatening the Everglades, including water management,  soil loss, eutrophication,
habitat alteration and mercury contamination.

   This project uses a statistical, probability-based sampling strategy to select sites
for sampling. Samples were collected from the freshwater wetland portion of the
Everglades and Big Cypress. The study area extended from Lake Okeechobee
southward to the mangrove fringe on Florida Bay and from the ridge along the urban,
eastern coast westward into  Big Cypress National Preserve (Figure 8). The
distribution  of the 200 canal sample sites and the 500 marsh sample sites is shown in
Figure 14. The samples represent the ecological condition in over 750 miles of
canals and  over 3,000 square miles of freshwater marsh.  Canals were sampled in
September 1993 and 1994, and May 1994 and  1995 (about 50 sites per sampling
cycle). Marshes were sampled in April 1995, September 1995 and  1996, and May
1996 (about 125 sites per sampling cycle). This corresponds to two dry (April and
May) seasons and two wet (September) seasons for both systems over a two-year
period.  Because the study involved sampling remote locations throughout an
extensive area, each marsh sampling event was performed by two teams using
helicopters  equipped with floats.  It took 8 or 9 days for the two teams to
simultaneously sample 125 sites while moving from the south upstream to the north.
A second phase of intensive sampling, performed at about 250 marsh sites during
1999, is described in companion reports. All reports and data for the study are
available on the internet at .

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
           May 1995
           September 1995
           May 1996
           September 1996
       FIGURE 1 4. The 200 canal sampling stations (left) and 500 marsh sampling stations (right).
          The media sampled at each site include surface water (Figure 15), canal
       sediment, marsh soil (Figure 16), algae (Figure 17), and prey fish (Figure 18).  The
       study sampled three physiographic regions: Everglades ridge and slough; marl
       prairie/rocky glades; and Big Cypress Swamp.

          This study permits a consistent, synoptic look at indicators of the ecological
       condition throughout the freshwater canal and marsh system. This large-scale
       perspective is critical to understanding the impacts of different factors (such as
       phosphorus and mercury distributions throughout the canals and marsh, habitat
       alteration, or hydropattern modification) on the entire system rather than at individual
       locations or in small areas. Looking only at isolated sites in any given area and
       extrapolating to the larger system can give a distorted perspective.  This study is

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                                             SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
FIGURE 1 5. Water samples were collected at
each site and analyzed for nutrients, mercury, and
other constituents.
FIGURE  1 6. A typical peat soil core collected
from an Everglades wet prairie.
unique to South Florida:  its extensive spatial
coverage and sampling intensity are
unprecedented; its probability-based sampling
approach permits quantitative statements about
ecosystem condition.

   A key advantage to this study's probability-
based statistical sampling approach is that it
allows one to estimate, with known confidence
and without bias, the current status and extent of
indicators for the condition of ecological
resources'89'. Also, indicators of pollutant
exposure and habitat condition can be used to
identify associations between human-induced
stresses and ecological condition. This design
has been reviewed by the National Academy of
Sciences, and the USEPA has applied it to
lakes, rivers, streams, wetlands, estuaries,
forests,  arid ecosystems and agro-ecosystems
throughout the United States'10'11'.
FIGURE  1 7. Well-defined periphyton mats are a
defining characteristic of the Everglades ridge and
slough complex.
                                                 FIGURE  18.
                                                 marsh.
              Sampling prey fish in a sawgrass

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
   PROBABILITY  SAMPLES
      A defining feature of the
   Everglades is its large spatial scale;
   hence, to monitor restoration
   effectiveness it is essential to
   determine the area of the
   Everglades that is subject to various
   human impacts.  This study employs
   probability-based sampling in order
   to accomplish this.  Probability
   samples are samples where every
   member of the population has a
   known chance of being selected
   and the samples are drawn at
   random. Every location in the study
   area has an equal chance of being
   sampled, so the results of this
   project are representative of the
   spatial distribution of parameters
   that are being measured.
   Therefore, the sampling design is
   not biased to favor one marsh type
   over another (e.g., sampling only
   the marshes next to a road because
   it is easier, avoiding sawgrass
   because it is unpleasant to sample
   in, or selecting a canal location
   because it looks good or bad). This
   means that the results can be used
   to estimate with  known confidence
   the proportion (extent) and
   condition of that resource. The risk
   to any ecological resource from the
   multiple environmental threats in
   South Florida is a direct function of
   the extent and magnitude of both
   the threat and the ecological
   effects.
   Parameters measured at each site can be used
to answer questions on multiple issues including:

 •  Water management (e.g., water depth at all
    sites)
 •  Water quality and eutrophication (e.g.,
    phosphorus concentrations in water and soil,
    cattail distribution)
 •  Habitat alteration (e.g., wet prairie, sawgrass
    marsh and cypress plant community
    distribution)
  •  Mercury contamination (e.g., mercury in
    water, soil, algae, and preyfish)

   Specific questions related to Everglades
restoration goals that this study answers include:

 •  How much of the marsh or canal system has
    a total phosphorus concentration greater than
    50 parts per billion (ppb), the Phase I
    phosphorus control goal, or 10 ppb, the
    approximate natural marsh  background
    concentration?
 •  How much of the marsh is dominated by
    sawgrass?  Wet prairie? Cattail?
 •  How much of the marsh still has the natural
    oligotrophic periphyton mat?
 •  How much of the marsh area is dry, and where?
 •  How much of the marsh soil has been lost due
    to subsidence?
 •  How much of the marsh has prey fish with
    mercury levels that present increased risk to
    top predators such as wading birds?
  •  What water quality conditions are associated
    with marsh zones of high mercury
    bioaccumulation ?

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                                              SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
      The probability-based sampling design is an assessment approach that
provides unbiased estimates of ecosystem condition with known confidence limits.
       Data from this study have been used by a variety of scientists and agencies for
    many purposes:

       •   Input to models that predict the Everglades' response to water management
          changes.
       •   Input to models that predict periphyton or vegetation changes  in response to
          phosphorus enrichment.
       •   Developing  empirical models in order to better understand interrelationships
          among mercury, phosphorus, sulfur, and carbon.
       •   Developing  water quality standards to protect human health, fish and wildlife.
       •   Understanding the relative risks of phosphorus and mercury.

       Monitoring is important for determining ecosystem condition,  identifying threats,
    and evaluating environmental restoration efforts.  As portions of the Comprehensive
    Everglades Restoration Plan are implemented, a system-wide monitoring program is
    needed.  Monitoring objectives include:

       •   Documenting status and trends;
       •   Determining baseline variability;
       •   Detecting responses to  management actions;
       •   Improving the understanding of cause and effect relationships.

       This South Florida Ecosystem Assessment Project provides such information system-
    wide for the freshwater Everglades marsh. The next sections describe ecosystem status
    based on the sampling program in canals and marshes from 1993 to 1996.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
WATER   MANAGEMENT
          The historic Everglades was defined in part by water: highly seasonal rainfall;
       slow, unimpeded, sheetlike water flow; and a large storage capacity that prolonged
       wetland flooding. These characteristics, along with subtle changes in ground surface
       elevation of only a few feet,  produced a variety of water depths and hydroperiods
       (duration of surface water inundation).  Because changes in water caused many of
       the harmful changes to the historic Everglades, water is key to restoration. Rainfall
       and the general patterns in water depth observed from 1993 to 1996 are described in
       this section.

          Rainfall is highly seasonal, with about 80% falling during the May to October wet
       season (Figures 19 and 20). Rainfall during the 1993-1996 sampling period was
       above average. Discharge through  public water pumping stations is also highly
       seasonal.  For example, at  S-8, a pumping station that provides flood control for part
       FIGURE 19.  A typical intense rain event in the
       slough-wet prairie complex during the summer wet
       season.
       FIGURE 21. The slough-wet prairie complex
       during the dry season.
                                                              1993
            1994
1995
1996
FIGURE  2O. Monthly rainfall (inches) from
1993 to 1996 at S-8, a pumping station that
provides flood control for part of the EAA by
discharging into the Everglades.
                                                               1993
             1994
 1995
 1996
 FIGURE 22.  Monthly discharge at S-8.
 Discharge varies from zero to several thousand
 cubic feet per second in response to rain events.

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                                                    SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
       of the Everglades Agricultural Area, discharge varies from zero during dry times to
       several thousand cubic feet per second in response to rain events (Figure 22).
     Dry  season
     April 1995
   Marsh water depths vary greatly with time and location (Figures 21, 23 to 25).
Water depths are deepest immediately upstream of levees that impede the natural
flow of water, such as the southern  portions of Arthur R. Marshall Loxahatchee
National Wildlife Refuge (the Refuge) and Water Conservation Areas 2 and 3A
(Figure 23).  Although all of these long hydroperiod areas remained wet during  the
study period, the unnaturally deep water depth of over five feet was observed within
Water Conservation Area 3 where the L-67 levee prevents sheetflow to the south.
                                           Shorter hydroperiod portions of the
                                           marsh are subjected to annual periods
                                           of drying.  During  both wet seasons the
                                           entire marsh was  inundated, while in
                                           April 1995 and May 1996 16% and 29%
                                           of the Everglades marsh was dry.
 Wet  season
September 1995
     Dry season
      May 1996
                     Wet season
                   September 1996
                              -2
                                                                 1994
                                                                            1995
                                                                                        1996
                                                        FIGURE 24. Mean monthly water depth at four
                                                        marsh locations. Red circles indicate when sampling
                                                        occurred. See Figure 23 for locations.
                                                         r
FIGURE  23. Water depth in the marsh system during the
four sampling events.  Colored squares indicate the location of
water depth gauges used for Figure 24.

                                                  FIGURE 25. The slough-wet prairie complex
                                                  during the wet season in Everglades National Park.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
WATER  QUALITY PATTERNS
       CONDUCTIVITY
         Water conductivity is useful
       for understanding the source of
       the water and its flow path.
       Precipitation in the Everglades
       has very low ionic content, with
       specific conductivity of volume-
       weighted annual precipitation
       of about 10 micromhos/cm(12).
       In contrast, the conductivity of
       water discharged from the EAA
       during the wet season is about
       100 times higher (1,000
       micromhos/cm).  Conductivity
       exhibits pronounced seasonal
       and spatial patterns in the
       Everglades (Figures 26 and
       27).  Very low conductivity in
       Big Cypress, the western
       portions of Water Conservation
       Area 3A and the interior of the
       Refuge (less than 100
       micromhos/cm) indicates that
       these areas are largely rainfall-
       driven.  Higher conductivity
       water is transported
       downstream in canals draining
       the EAA, and there is a
       progressive decrease
       southward to the Park with
       dilution by rainfall and marsh
       water.  Water Conservation
       Area 2 has the highest marsh
       conductivity. Marsh
       conductivity is higher in the dry
       season due to less dilution by
  •  0-199
  • 200 - 399
   400 - 599
   600 - 799
   800 - 2200
FIGURE 26. Surface water conductivity (micromhos/cm) in the marsh
(top) and canals (bottom) during the dry season (left) and wet season
(right).

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                                                SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
  rainfall, the drying of the marsh and subsequent evapoconcentration, and the
  continuing influence of canal water. Pronounced conductivity gradients clearly
  indicate pathways of water flow throughout the canal-marsh system and the extent to
  which the water management system and its operation influences water quality.
                            Canal
                 Conductivity (micromhos/cm)
          Marsh
Conductivity (micromhos/cm)
                    200   400    600    800  1000

                        Sulfate (ppm)
   200   400    600   800  1000

       Sulfate (ppm)
                   Total Organic Carbon (ppm)
Total Organic Carbon (ppm)
LNWR -

VVCAoN
VVCAoo -
CM p

BCNP -


I
1






i





i



i

                                                           0
     10
20
30
FIGURE 27.  Seasonal comparison of surface water conductivity (micromhos/cm), sulfate (ppm) and total
organic carbon (ppm) by latitudinal subarea for canals (left) and marsh (right).  Blue bars are wet season,
orange bars are dry season.  EPA north of AA is the Everglades Protection Area north of Alligator Alley.
WCA3N is WCA3A north of Alligator Alley. WCA3A S is WCA3B and WCA3A south of Alligator Alley. TT is
Tamiami Trail.  The median is reported.
40

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
       SULFATE
          Sulfate is common in nature and is a natural ingredient of rainfall, surface water
       and groundwater. Sulfur is also
       a secondary nutrient required
       for crops. Agricultural sulfur is
       applied to EAA soils in order to
       make plant nutrients more
       readily available'13'14).
           Marsh and canal surface
       water sulfate from 1993 to 1996
       exhibited strong gradients and
       seasonality (Figures 27 and 28).
       Rainfall sulfate concentrations
       are less than 1  ppm(12). Marsh
       background concentrations of
       less than 2 ppm are found only
       in the interior rainfall-driven
       portion of the Refuge, and
       portions of the marsh that are
       distant from the influence of
       canal water deliveries, such as
       western Water Conservation
       Area 3, Big Cypress, and
       portions of the Park. The
       highest sulfate concentrations
       of over 100 ppm were observed
       in canals within the  EAA during
       the wet season.  The highest
       marsh concentrations are found
       in Water Conservation Area 2.
       Concentrations progressively
       decrease to the south and west.
       The lowest concentrations are
       found in the Refuge, Big
       Cypress, and the  marsh south
       of Tamiami Trail during the wet
FIGURE 28. Surface water sulfate (ppm) in the marsh (top) and
canals (bottom) during the dry season (left) and wet season (right).

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                                         SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
  Pronounced spatial gradients in surface water conductivity and sulfate
 throughout the canal and marsh system vividly demonstrate that the canal
 system is a conduit for transport.  Water management affects water quality.
   Dry Season £ a^
      Canal
     5- 9
     10 - 19
     20-29
     30-39
     40 - 100
                                                       season (median of less than 2
                                                       ppm).

                                                         These spatial patterns
                                                       indicate that the canal system
                                                       delivers sulfate from the north
                                                       into Everglades marshes.
                                                       Sulfate is of particular
                                                       ecological concern since
                                                       slightly elevated sulfate
                                                       concentrations have been
                                                       hypothesized to affect
                                                       mercury cycling by stimulating
                                                       mercury methylation'15'.
TOTAL  ORGANIC
CARBON
   The highest total organic
carbon was observed in
canals within the EAA
(Figures 27 and 29). Total
organic carbon also exhibits
high seasonality with highest
values during the dry season.
Carbon is important in that it
also plays a role in mercury
cycling'15'.  The specific
effects of carbon and sulfur on
mercury cycling are the
subject of ongoing research.
FIGURE 29. Surface water total organic carbon (ppm) in the marsh (top)
and canals (bottom) during the dry season (left) and wet season (right).

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
SOIL  SUBSIDENCE
         Soil is a key defining characteristic of an ecosystem, and soil preservation is an
       important aspect of ecosystem protection. The South Florida Ecosystem Restoration
       Task Force and the Comprehensive Everglades Restoration Plan have adopted
       objectives and success indices in order to define restoration goals, track ecosystem
       status, and measure restoration effectiveness. Among these is restoring the natural
       rates of organic soil and marl soil accretion, and stopping soil subsidence'7'.

         A variety of soil types are found in the Everglades. Soils to the west in Big
       Cypress Swamp are primarily sandy, while the wetland soils of the central  Everglades
       are primarily organic peat (see Figures 5 and 16). Peat soils are formed by decaying
       plant matter. Another major soil type found within Everglades wetlands is  a calcitic
       mud (marl), commonly found in the shallower peripheral marshes of the Everglades
       subjected to shorter periods of surface water inundation (Figure 30).  Marl is found
       in association with thick algal mats, called periphyton, which are able to precipitate
       calcium carbonate from the water column'16'.

         The Everglades once contained the largest single body of organic soils in the
       world, covering over 3,000 square miles, and accumulating to a thickness of up to 17
       feet in what is now the EAA(17). The origin and perpetuation of peat and marl soils is
       greatly dependent upon water depth and the duration  of surface water inundation,
       and the resulting wetland vegetative communities. Diminished surface water
       inundation  can cause soil loss or changes in soil composition, which may in turn
       result  in  altered vegetative communities. These altered plant communities may
       cause further changes in soil type and thickness as this different plant community
       eventually decomposes and forms altered soil.
                                 Peat soils are subject to subsidence and surface
                              elevation loss when drained.  Oxidation, burning and
                              compaction are considered the dominant subsidence
                              forces, and from a practical standpoint are irreversible.
                              An inch of Everglades peat that takes a century to form
                              can be lost within a few years.  Early in the twentieth
                              century the deep peat soils (mostly formed by decaying
                              sawgrass) of the 700,000 acre EAA were drained to
                              facilitate agricultural production.  The process  of soil
                              formation was reversed  in 1906 when the first canals were
FIGURE 3O. An Everglades soil
core with peat overlaying marl.

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                                           SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
cut from Lake Okeechobee through the EAA to the coast'18'.  Subsequent subsidence
within the EAA and efforts to control it on agricultural lands are well documented.

   In contrast, prior to this study subsidence of peat soils during the last 50 years
within the Everglades Protection Area was poorly documented. Soil loss in the public
Everglades is largely due to water management practices during the 1900s. The
major canals draining the EAA extend southeast through the Everglades to the
Atlantic Ocean and were completed by 1917. However, unimpeded surface water
flow from the EAA south through the Everglades to the Park, Florida Bay, and the
Gulf of Mexico still occurred until the late 1950s, when levees were constructed
forming the southern  boundary of the EAA. During the early 1960s additional levees
were completed that partitioned the Everglades into the Water Conservation Areas.
By the 1960s Everglades surface water depths, flow,  and  inundation periods had
been greatly altered'19'.
   Soil thickness measured at 479 sampling
sites from 1995 to 1996 is presented in
Figures 31 and 32, along  with soil
thicknesses  reported by Davis in  1946(20).
Soil thicknesses throughout the study area
vary greatly  from 0 feet to over 12 feet.  The
deepest soils are the peat deposits within the
Refuge with  a median soil thickness of over
9 feet. Median soil thicknesses for
remaining portions of the  study area were
4.2 feet in Water Conservation Area 2,
1.2 feet in Water Conservation Area 3A north
of Alligator Alley, 2.8 feet in Water
Conservation Area 3 south of Alligator Alley,
1.0 feet in the Park, and 1.0 feet in Big
Cypress. About 19% of the Everglades had
a soil  thickness less than  one foot, while
40% had a soil thickness  of over three feet.
The deepest peat in the Everglades outside
of the Refuge is within those portions  of
Water Conservation Area 2 and southern
Water Conservation Area 3 which typically
stay inundated year-round.
            Organic Matter (percent)
            20
                   40
                          60
                                  80
               Bulk Density (glee)
               Soil Thickness (feet)
                                        100
LNWR
WCA2
WCA3N
WCA3S
ENP
BCNP

	




















LNWR
WCA2
WCA3N .
WCA3S .
ENP
BCNP


| 	 |











                                        10
FIGURE 3 1. Spatial variation in soil organic matter,
bulk density, and thickness throughout the Everglades
marsh system at about 480 sampling sites. The median is
reported.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
FIGURE 32. Soil thickness (feet) as reported by Davis in 1946 (left) and at
479 sites in 1995 to 1996 (this study).
                                                              Figure 33 presents the
                                                           change in peat thickness
                                                           throughout the Everglades
                                                           during the last 50 years.
                                                           Soil volumes reported in
                                                           1946 and 1996 and the
                                                           difference have been
                                                           calculated bysubarea.
                                                           Since the 1946 peat
                                                           thickness was reported in
                                                           2-foot intervals, soil
                                                           volume differences from
                                                           1946 to 1996 are
                                                           presented as a range.
                                                           Calculation of soil loss
                                                           during the last 50 years
                                                           indicates that the portion of
                                                           Water Conservation Area
                                                           3 north of Alligator Alley
                                                           lost between 39% and
                                                           65% (2.0to6.0x108m3)
                                                           of its soil. This area was
                                                           reported to have 3 to 5
                                                           feet of peat in 1946, while
                                                           the present study found
                                                           only 1 to 3 feet of soil,
                                                           with less than 1  foot in
                                                           some  areas.  The
                                                           southeastern part of
                                                           Water Conservation Area
                                                           3 (WCA3B) and the
                                                            northeast Shark Slough
                                                            portion of the Park may
FIGURE 33. Soil loss (feet) from 1946 to 1996 for the Everglades.          have lost up to 3 feet Of
                                                           soil, representing a 53%
       loss of volume in Northeast Shark Slough, and a 42% loss of volume in WCA3B.
       These three portions of the Everglades, which encompass about 200,000 acres, have
      Minimum
        Loss
                         No
                       Loss
Maximum
  Loss

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                                           SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
been subjected to decreased surface water inundation since completion of the Water
Conservation Areas about 40 years ago. During the last 50 years the Everglades
Protection Area has lost up to 28% of its soil (17 x 108 m3).  The accretion of soil
within portions of the Park suggested by Figure 33 may be an artifact of the 1946
sampling method. Davis (1946) mentions seven areas of detailed sampling, none of
which were within what is now the Park.

    Soil organic  matter observed during 1995 and 1996 at 479 sites ranged from
<1 % to 97% (Figures 31 and 34).  Peat soils are highly organic, while marl soils and
sandy soils are primarily mineral. The highest organic matter content was found in
the thick peat soils within the Refuge with a median of 93%. Water Conservation
Area 2A and Water Conservation Area 3 south of Alligator Alley also had  soils
exceeding 75% organic matter. These highly organic zones coincide with  the deeper
soil portions of the system.  The area of maximum soil loss within Water
Conservation Area 3 north of Alligator Alley had a median soil organic matter content
FIGURE 34. Soil organic matter (percent, left) and bulk density (g/cc, right).  Data are for the 0 to 10 cm soil
depth.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
     During the last 50 years, over one-half of the soil has been lost from portions of
    the Everglades.  Water management must be improved to maintain marsh soils if
    the plant communities and wildlife habitat of these wetlands are to be preserved.
       of 63%, the lowest within the Water Conservation Areas.  Soils in the Park, which
       include the peat soils within the Shark Slough trough as well as the marl soils of
       adjacent shorter hydroperiod areas, had a median organic content of 31 %. The
       sandy soils of Big  Cypress had a median organic matter content of only 11%.
       Portions of the Park outside the central Shark Slough trough also  had lower organic
       matter content, usually in the 10% to 20% range.

         Soil bulk density at 475 marsh sites in 1995 and 1996 ranged from 0.05 to 1.50 g/
       cc (Figures 31 and 34). The highly organic peat soils of the Refuge had the lowest
       bulk density with a median of 0.06 g/cc as compared to the mineral soils of Big
       Cypress, which  had  a median of 0.75 g/cc.  The median bulk density for Water
       Conservation Area 3 north of Alligator Alley was 0.21 g/cc, the highest in the Water
       Conservation Areas. Within the Water Conservation Areas, this portion of northern
       Water Conservation  Area 3 had the lowest organic matter content, the highest bulk
       density, and the greatest soil loss.

         All of these observations are suggestive of formerly deeper peat soils being
       subjected to drier  conditions due to water management changes over the  last
       50 years. Surface water inundation has been reduced, soils have subsided, and the
       resulting surface soil has become less organic. This South Florida Ecosystem
       Assessment Project is the first effort to consistently document soil thickness,  bulk
       density and organic matter throughout the Everglades system.


EUTROPHICATION  AND  HABITAT

         Historically, the Everglades ecosystem was nutrient poor, with surface water
       phosphorus concentrations less than 10 parts per billion (ppb)(21).  Rainfall was the
       dominant source of external phosphorus, and the hydrology of the marsh was rainfall-
       driven, with slow overland sheet flow supplying water to downstream wetlands.
       There were no canals in the Everglades region prior to the early part of the twentieth
       century.  This natural nutrient-poor condition resulted in a  diversity of wildlife habitats,
       such as sloughs, sawgrass marshes, and wet prairies which included well-developed
       periphyton communities.

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                                          SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
   Today, the canal system is a conduit for nutrient transport. Nutrient loading from
the EAA and urban areas has significantly increased phosphorus concentrations in
the downstream Water Conservation Areas and the Park, causing eutrophic impacts
to these wetland systems. Among the progressive eutrophic impacts are altered
periphyton communities, loss of water column dissolved oxygen, increased soil
phosphorus content, conversion of wet prairie and sawgrass plant communities to
cattail, and subsequent loss of important wading bird foraging habitat. These
collective changes impact the structure and function of the aquatic ecosystem.
   A phosphorus control program was initiated in the 1990s in order to prevent the
further loss of Everglades plant communities and wildlife habitat due to nutrient
enrichment. Phase I of the program requires that discharges from the EAA into the
Everglades be at 50 ppb total phosphorus (TP) or less.  Control is to be achieved by
a combination of about 47,000 acres of treatment wetlands, referred to as
Stormwater Treatment Areas (STAs) (Figure 35), and agricultural Best Management
Practices (BMPs). The first STA (about
10% of the  Phase I treatment acreage)
began  discharging in 1994, and BMPs
were required to be in  place by 1995.  The
1993 to 1996 sampling period reported
here corresponds to the phase-in period
for EAA BMPs, as during these years the
percentage of EAA farms with phosphorus
control BMPs in place  went from 0 to 100.
The BMPs have resulted in about a 50%
three-year cumulative  phosphorus load
reduction from the EAA basin to the
Everglades Protection Area, as compared
to the load that would have been expected
without BMPs(22).  This report documents
the 1993 to 1996 phosphorus conditions
and habitat during the  initiation of
                              Stormwater
                               Treatment
                                 Areas
            Everglades
            Agricultural
               Area
phosphorus control efforts.
FIGURE 35. Location of Phase I phosphorus control
program Stormwater treatment wetlands. In combination
with agricultural best management practices they are to
decrease phosphorus to 50 ppb or less prior to discharge
into the Everglades (adapted from SFWMD).
   Water and soil samples were analyzed
for phosphorus and other indicators of nutrient enrichment, such as nitrogen,
chlorophyll a, and alkaline phosphatase activity.  Relationships between phosphorus
concentrations in water and soils, plant communities, and periphyton presence were

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
       noted to identify correlations between nutrient enrichment and habitat in the
       Everglades ecosystem.
          Canal TP concentrations exhibit strong north to south gradients. Concentrations
       in EAA canals were significantly higher than those in any other area sampled
       (Figures 36 and 37), with a wet season median of 149 ppb (as compared to 13 ppb in
                                                   canals near the Park). About 80% of
                                                   the canal miles in the EAA had TP
                                                   concentrations greater than the
             ^               _                    Phase I STA design target of 50 ppb.
       {-*|~ ' x       \      '   f~~V\r ^>   This drops to 15% for canals in the
       \    \   \    '         V   \   /I    "   area between Alligator Alley and
                                                   Tamiami Trail, and to only 1% for
                                                   canals in the area south of Tamiami
                                                   Trail.  North of Alligator Alley wet
                                                   season concentrations tend to be
                                                   higher, while to the south dry season
                                                   concentrations tend to be  higher.
                                                   Overall, 44% of canal miles had
                                                   water TP concentrations greater than
                                                   50 ppb.
                                                      Marsh sites also exhibit spatial
                                                   gradients. Marsh TP concentrations
                                                   were notably higher in the dry
                                                   season, with the highest
                                                   concentrations most consistently
                                                   occurring in northeast Water
                                                   Conservation Area 2A.  The interior
                                                   of the Refuge tended to have very
                                                   low concentrations, indicative of its
                                                   rainfall-driven status (Figures 36
                                                   and 37).  Median TP concentrations
                                                   throughout the Everglades system
                                                   ranged from less than 10 ppb in the
                                                   marsh during the wet season (Figure
                                                   38), to almost 50 ppb in the canals
                                                   during the dry season.
FIGURE 36.  Surface water total phosphorus (ppb) in the
marsh (top) and canals (bottom) during the dry season (left) and
wet season (right).

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                                                SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
                        Canal
                   Total Phosphorus
         0          50          100         150
            Alkaline Phosphatase Activity
                                     Marsh
                               Total Phosphorus
                      0      10     20     30     40     50
                        Alkaline Phosphatase Activity
LNVVR-
WCA2 -
WCA3N -
WCA3S "
ENP-
BCNP-
I
EEP

i


i
	 b
^m

                                                          01234

FIGURE 37. Seasonal comparison of surface water total phosphorus (ppb) and alkaline phosphatase activity
(micromoles/hr) by latitudinal subarea for canals (left) and marsh (right). Blue bars are wet season, orange bars are dry
season. Alkaline phosphatase is an enzyme that makes phosphorus available for biological uptake. Lower activity is
indicative of higher phosphorus availability.  EPA north of AA is the Everglades Protection Area north of Alligator Alley.
WCA3 N is WCA3A north of Alligator Alley (AA). WCA3 S is WC3B and WCA 3A south of Alligator Alley. TT is Tamiami
Trail. The median is reported.
   Similar patterns existed for
alkaline phosphatase activity
(APA) (Figures 37 and 39).
Alkaline phosphatase is an
enzyme that makes
phosphorus available for
biological uptake. Higher
activity indicates low
phosphorus concentration.  In
general, APA throughout the
marsh and  canals exhibited
strong gradients and the
expected inverse relationship
with TP in water. The lowest
enzyme activities (median of
 100
                                         	 Canal Wet
                                             Canal Dry
                                         	 Marsh Dry
                                             Marsh Wet
                              50
                    Total Phosphorus (ppb)
100
FIGURE 38. Cumulative distribution of frequency for total phospho-
rus by season in the marsh and canal systems. The y-axis indicates
percent of canal miles or percent of marsh area.  The 50% line is the
median.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
         FIGURE 39. Surface water alkaline phosphatase activity (micromoles per hour) in the marsh (left, September
         1995) and canals. Canal data are for dry season (middle) and wet season (right).
       about 0.1 micromoles/hr) were observed in EAA canals where water TP
       concentrations were highest.  The highest enzyme activities were found during the
       wet season in the Refuge (median of 4.2 micromoles/hr) and interior portions of the
       Park (median of 2.5 micromoles/hr).

          Phosphorus in marsh soils can be an indicator of enrichment. Soil type varies
       greatly throughout the Everglades, as the median bulk density of soil varied from
       about 0.06 g/cc in the Refuge to 0.75 g/cc in Big Cypress (Figure 34).  Soil
       phosphorus is expressed in Figure 40 as milligrams phosphorus per kilogram  of soil,
       and as micrograms phosphorus per cubic centimeter of soil in order to remove the
       influence of varying soil bulk density.  Depicted in this manner, Water Conservation
       Area 3A north of Alligator Alley and northern Water Conservation Area 2A have the
       highest soil phosphorus in the portion of the Everglades with peat soil. In contrast,
       the Refuge interior has much lower soil phosphorus than any other part of the
       system. Results reported here for 1995 to 1996 are similar to those obtained by
       others in the early 1990s for the Refuge and Water Conservation Areas 2 and  3(21).
       This study is the first to perform systematic synoptic sampling of soil phosphorus
       throughout all of the Everglades Protection Area and Big Cypress.

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                                           SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
FIGURE  4O. Soil total phosphorus expressed as milligrams per kilogram (left) and as micrograms
per cubic centimeter (right).  Data are for the 0 to 10 centimeter soil depth.

   The natural mosaic of vegetation community types is a defining characteristic of
the Everglades.  Wet prairies and open water areas void of dense emergent
macrophytes serve as  preferred wading bird foraging habitat. Factors driving
vegetation community  composition include hydroperiod, salinity, nutrients, and
disturbances such as fire, frosts, and hurricanes.  Field crews documented the
dominant and secondary plant communities at the marsh sampling sites.  A simple
vegetation classification method was used to qualitatively group marsh habitat into
several classes,  including sawgrass marsh and wet prairie.  Field crews also noted  if
cattail (Typha domingensis) was present at a site. Cattail is a native species known
to respond to phosphorus enrichment such that  it can replace wet prairies and
sawgrass.
   Wet prairie and sawgrass marsh are the two dominant plant communities in the
Everglades. Sawgrass was dominant at 47% of the 479 sampling sites and the wet
prairie-slough complex was dominant at 44% of the sites (Figures 41 to 43). Wet
prairie tends to dominate in the Refuge, and in wetter portions of WCA3.  Sawgrass
tends to dominate north of Alligator Alley and in Water Conservation Area 2, while the
Park contains a mix of the two communities. Cattail presence along with soil
phosphorus is shown in Figure 43.  Cattail was present at 10% of the sampling sites.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
FIGURE 4 1 . Aerial view of the Everglades showing the mosaic of
sawgrass marsh and wet prairie plant communities.
                                                               FIGURE  42. Sawgrass marsh with
                                                               high plant density.

                                                   Cattail was prevalent in the northern
                                                   portions of Water Conservation Areas 3A
                                                   and 2A, and sites that were generally in
                                                   close proximity to canals.  There tends to
                                                   be a strong association between cattail
                                                   presence and  soil phosphorus or proximity
                                                   to canals.  As  soil phosphorus increases,
                                                   there is a greater likelihood that cattail will
                                                   be present'23'.
    Soil TP
  > 870 mg/kg
FIGURE 43. The spatial distribution of the wet prairie
(blue) and sawgrass marsh (green) vegetation
communities. Red indicates the presence of cattail. Yellow
indicates soil phosphorus greater than 870 mg/kg(23).
FIGURE 44. Everglades eutrophication promotes
cattail expansion.

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                                          SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
          Low phosphorus conditions must be restored if natural
    Everglades periphyton and plant communities are to be maintained.
   Well-developed attached or floating periphyton
mats are a defining characteristic of Everglades
habitats, particularly wet prairies and deeper slough
areas (Figures 2, 17, 45 and 46). These biologic
communities serve multiple functions such as
providing oxygen to the water column for fish,
removing calcium carbonate from the water and
depositing it as soil,  removing phosphorus from the
water to very low levels, and serving as a food web
base'21'. These periphyton communities are
sensitive to very slight increases in nutrient
concentration,  with increases in phosphorus
condition causing mat disappearance or changes to
the periphyton  assemblage,  including species
composition and  biomass. Consequently, periphyton
are a sensitive indicator of marsh ecosystem status.

   Periphyton  mats were found at 67% of the
sample sites during 1995-1996.  The species
composition of these mats was  not documented.
Mats were less common in the Refuge and the
northern portions of Water Conservation Areas 2A
and 3A (Figure 46).  With the exception of the
Refuge, the areas where periphyton mats were not
found tend to be areas where wet prairies are
absent and sawgrass or cattail dominate. In
communities where plant density, height, and above
ground biomass are  high, shading effects may
preclude the development of periphyton mats and
wet prairie communities. Elevated phosphorus may
also explain the absence of the mat community, or
a change in periphyton species composition to
species that are more nutrient tolerant'21'.
FIGURE 45. Underwater view of a wet prairie
in southern Water Conservation Area 3 with
periphyton attached to macrophytes.
                         Present
                         Absent
FIGURE 46. Presence of a periphyton mat
community. Green indicates presence while
black indicates absence.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
KEY  FINDINGS  AND  MANAGEMENT
IMPLICATIONS
         This report describes the condition of the Everglades system during the extensive
       1993 to 1996 synoptic sampling effort. This represents the condition prior to initiation
       of the Comprehensive Everglades Restoration Program.  Study findings have various
       management implications.

         • Pronounced water quality gradients: Water discharged from Everglades
           Agricultural Area canals is loading the public Everglades with excess
           phosphorus, carbon, and sulfur.  Concentrations progressively decrease
           downstream.

         • Canals are a conduit for pollutant transport: The canal system is an effective
           conduit for the transport of degraded water into and through the Everglades
           marsh system. Water management clearly affects water quality.  Downstream
           water quality would be improved if delivery canals were eliminated or if they were
           operated to maximize the diluting influence of rainfall, cleaner marsh water and
           surface water sheetflow.

         • Varying water quality:  Surface water conductivity, phosphorus,  carbon,
           nitrogen and sulfur vary greatly throughout Big Cypress and the Everglades and
           are dependent upon  location, time of year and  water management practices.
           Long-term sampling  is required in order to differentiate between natural
           seasonality, inter-annual variability, and the effects of specific restoration actions
           taken under the adaptive assessment  approach.

         • Phosphorus enrichment: As of 1995 to 1996, about 44%  of the Everglades
           canal system and 4% of the Everglades marsh area had total phosphorus
           concentrations exceeding the Phase I  50 part per billion control target.  Once all
           phosphorus control efforts are in place (2007),  probability-based sampling can
           be repeated to document the effectiveness of these efforts.

          • Marsh habitat a mosaic: Wet prairie and sawgrass marsh were the two
           dominant plant communities in the Everglades, representing 44% and 47% of
           the sites sampled. Cattail was present at 10% of these sites, and was
           associated with elevated soil phosphorus or proximity to canals.  Water quantity
           and water quality must be managed to maintain these important habitats, and
           halt further encroachment of cattail.

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                                          SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
   • Periphyton conspicuous: Well-defined periphyton mats, a defining
    characteristic of the Everglades marsh complex, were found at 67% of the
    sample sites.  Water quality should be maintained such that oligotrophic
    periphyton  mats are perpetuated.

   • Soil loss in the Everglades Protection Area: From 1946 to 1996, about one-
    half of the peat soil was lost from drier portions of the Everglades.  This is a
    serious problem that must be addressed. Water management must be improved
    to maintain remaining marsh soils if the plant communities and wildlife habitat of
    these wetlands are to be preserved.

   • Ecological condition varies by location and time: The ecological condition of
    the Everglades varied greatly with location.  Rainfall-driven portions of the
    system that are distant from the influence of canal water, such as the interior of
    Arthur R. Marshall Loxahatchee National Wildlife  Refuge and the southwest
    portion of Water Conservation Area 3A, were found to have good water quality
    and low soil phosphorus. The interior of Loxahatchee National Wildlife Refuge
    tended to have the most pristine water quality and the lowest phosphorus
    concentrations in peat soils. In contrast, northern Water Conservation Area 3A
    had poorer water quality, extensive soil loss due to water management, elevated
    soil phosphorus and cattail encroachment.  Water Conservation Area 2 had
    evidence of phosphorus enrichment and cattail encroachment, along with high
    sulfate and conductivity.  Big Cypress had good water quality and  no  obvious
    indications of phosphorus enrichment. Water quantity conditions at a given
    location vary with season and year.

   • Environmental threats interrelated: Ecological stressors such as water
    management, soil loss, water quality degradation, eutrophication, cattail
    encroachment and mercury contamination are often interrelated. Management
    actions must be holistic.

   This project provides a critical benchmark for assessing the ecosystem condition
and the effectiveness of Everglades restoration activities into the twenty-first century.
As Everglades protection efforts proceed, this probability-based sampling can be
repeated to document the effectiveness of these actions.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
     The South Florida Ecosystem Assessment Project documents conditions in the
      Everglades prior to ecosystem restoration efforts. This provides a benchmark
       for determining the effectiveness of future Everglades restoration activities.
REFERENCES
          REFERENCES  CITED

          1. United States Army Corps of Engineers and South Florida Water Management District.
            July 1999.  Rescuing an Endangered Ecosystem: the Plan to Restore America's
            Everglades. The Central and Southern Florida Project Comprehensive Review Study
            (The Restudy).  28 p.  

          2. United States Bureau of the Census. 1890 to 1990 United States census results.

          3. Davis, Steven M. and John C. Ogden. 1993. Everglades: The Ecosystem and Its
            Restoration. St. Lucie Press. Delray Beach, Florida. 826 p.

          4. Ogden, John C. 1993.   A Comparison of Wading Bird Nesting Colony Dynamics
            (1931-1946 and 1971-1989) as an Indication of Ecosystem Conditions in the Southern
            Everglades, pp. 533-570 in Everglades: The Ecosystem and Its Restoration. Davis,
            Steven M. and John C. Ogden (editors).   St. Lucie  Press. Delray Beach, Florida.
            826 p.

          5. Ingebritsen, S. E., Christopher McVoy, B. Glaz, and Winfred  Park. 2000.  Florida
            Everglades, pp. 95-106 in Land Subsidence in the  United States. Devin Galloway,
            David R. Jones and S. E. Ingebritzen, editors.  United States Geological Survey
            Circular 1182.  Denver, Colorado.  177 p.

          6. United States Army Corps of Engineers and South Florida Water Management District.
            October 1998.  Overview.  The Central and Southern Florida Project Comprehensive
            Review Study. 29 p.  

          7. Science Subgroup.  1997.  Ecologic and Precursor Success  Criteria for South Florida
            Ecosystem Restoration.  Report to the Working Group of the South Florida Ecosystem
            Restoration Task Force.  Planning Division.  United States Army Corps of Engineers.
            Jacksonville, Florida. < http://www.sfrestore.org/>

          8. Thornton, K. W., Saul, G. E. and Hyatt, D. E. 1994. Environmental Monitoring and
            Assessment Program Assessment Framework. United States Environmental Agency
            Report EPA/620/R-94/016.  Research Triangle Park, North Carolina. 47 p.

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                                           SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
9.  Stevens, Don L, Jr.  1997.  Variable Density Grid-based Sampling Designs for
   Continuous Spatial Populations.   Environmetrics vol. 8, p. 167-195.

10. Olsen, A. R., Sedransk, J.,  Edwards, D., Gotway, C. A., Liggett, W.  1999. Statistical
   Issues for Monitoring Ecological and Natural Resources in the United States.
   Environmental Monitoring and Assessment, vol. 54, p. 1-45.

11. United States Environmental Protection Agency. 1995.  Environmental Monitoring and
   Assessment Program (EMAP) Cumulative Bibliography.  United States  Environmental
   Protection Agency, Office of Research and Development.  EPA/620/R-95/006.
   Resarch Triangle Park, North Carolina.  44 p.

12. National Atmospheric Deposition Program. 2000.  National Atmospheric Deposition
   Program data, site FL11.   Accessed July 19,
   2000.

13. Coale, Frank J. 1994. Sugarcane Production in the EAA. pp. 224-237 in Everglades
   Agricultural Area (EAA): Water, Soil, Crop, and Environmental Management.
   University Press of Florida. Gainesville, Florida. 318 p.

14. Schueneman, T. J. and C. A. Sanchez.  1994.  Vegetable Production in the EAA. pp.
   238-277 in Everglades Agricultural Area (EAA): Water,  Soil, Crop, and  Environmental
   Management.  University Press of Florida.  Gainesville, Florida.  318 p.

15. Larry Fink and Peter Rawlik. 2000.  The Everglades Mercury Problem. Chapter 7 in
   Everglades  Consolidated Report.  January 1, 2000. South Florida Water
   Management District, 

16. Gleason, Patrick J. and Peter Stone. 1993. Age, Origin and Landscape Evolution of
   Everglades  Peatland. pp. 149-197 in Everglades: The Ecosystem and  Its Restoration.
   Davis, Steven M. and John C. Ogden (editors).  St. Lucie Press.  Delray Beach,
   Florida.  826 p.

17. Stephens, John C. and Lamar Johnson.  1951.  Subsidence of Peat Soils in the
   Everglades  Region of Florida.  United States Department of Agriculture Soil
   Conservation Service.  47  p.

18. Stephens, John C. 1956. Subsidence of Organic Soils in the Florida Everglades.
   Soil Science Society Proceedings,  pp. 77-80.

19. Light, Stephen S.  and J.  Walter Dineen.  1993. Water Control in the Everglades: A
   Historical Perspective, pp.  47-84  in Everglades: The Ecosystem and Its Restoration.
   Davis, Steven M. and John C. Ogden (editors).  St. Lucie Press.  Delray Beach,
   Florida.  826 p.

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SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT
          20. Davis, John H., Jr.  1943.  The Peat Deposits of Florida: Their Occurrence,
             Development and Uses.  Geological Bulletin No. 30.  Florida Geological Survey.
             Tallahassee, Florida. 247 pp.

          21. McCormick, Paul C., Susan Newman, ShiLi Miao, Ramesh Reddy, Dale Gawlik, Carl
             Fitz, Tom Fontaine and Darlene Marley. 1999.  Ecological  Needs of the Everglades.
             Chapter 3 in Everglades  Consolidated  Report.  January 1,  1999.   South Florida Water
             Management District,  

          22. South Florida Water Management District. 1999.  Everglades Best Management
             Practices Program.  Water  Year 1999:  May 1, 1998 through April 30, 1999. 5th
             Annual Report,  

          23. William W. Walker, Jr., and Robert H. Kadlec. 1996.  A Model for Simulating
             Phosphorus Concentrations in Waters  and Soils Downstream of Everglades
             Stormwater Treatment Areas.  August 16, 1996 draft.  108 p.
          OTHER   REFERENCES

             South Florida Ecosystem Restoration Task Force.  1999.  Maintaining the Momentum.
             Biennial Report to the U. S. Congress, Florida Legislature, Seminole Tribe of Florida,
             and Miccosukee Tribe of Indians of Florida. 24 p. 

             Stober, Q. J., R. D. Jones and D. J. Scheldt.  1995. Ultra Trace Level Mercury in the
             Everglades Ecosystem: A Multimedia Pilot Study. Water, Air and Soil Pollution vol.
             80, p. 1269-1278.

             Stober, Jerry, Daniel Scheldt, Ron Jones,  Kent Thornton, Robert Ambrose and Danny
             France.  1996.  South Florida Ecosystem Assessment: Monitoring for Ecosystem
             Restoration.  Interim Report.  EPA 904-R-96-008. USEPA Region 4 Science and
             Ecosystem Support Division and Office of Research and Development.  Athens,
             Georgia. 26 p.  

             Stober, Jerry, Daniel Scheldt, Ron Jones,  Kent Thornton, Lisa Gandy, Don Stevens,
             Joel Trexler and Steve Rathbun. 1998.  South Florida Ecosystem Assessment:
             Monitoring for Ecosystem Restoration. Final Technical Report - Phase I.  EPA 904-R-
             98-002.  USEPA Region 4 Science and Ecosystem Support Division and Office of
             Research and Development.  Athens, Georgia. 285 p. plus appendices.
             


          PHOTOGRAPHIC ACKNOWLEDGEMENTS

             Table of contents water control structure and  Figure 8: South Florida Water
             Management District; Figure 3:  Everglades National Park; All other photographs:
             Daniel Scheldt.

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