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A Review of the Florida Keys Carrying Capacity Study (2002)

Chapter: Appendix B Interim Review of the Florida Keys Carrying Capacity Study

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Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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Appendix B
Interim Review of the Florida Keys Carrying Capacity Study

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×
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Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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Interim Review of the Florida Keys Carrying Capacity Study

National Research Council

Division on Earth and Life Studies

Ocean Studies Board & Water Science and Technology Board

Committee to Review the Florida Keys Carrying Capacity Study

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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NATIONAL ACADEMY PRESS • 2101 Constitution Avenue, NW • Washington, DC 20418

NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

This report and the committee were supported by a grant from the United States Army Corps of Engineers. The views expressed herein are those of the authors and do not necessarily reflect the views of the sponsors.

Additional copies of this report are available from:

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Copyright 2001 by the National Academy of Sciences. All rights reserved.

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Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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THE NATIONAL ACADEMIES

National Academy of Sciences

National Academy of Engineering

Institute of Medicine

National Research Council

The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences.

The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. William A. Wulf is president of the National Academy of Engineering.

The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Kenneth I. Shine is president of the Institute of Medicine.

The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. William A. Wulf are chairman and vice chairman, respectively, of the National Research Council.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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The work of this committee was overseen by the Ocean Studies Board and the Water Science and Technology Board of the National Research Council.

COMMITTEE TO REVIEW THE FLORIDA KEYS CARRYING CAPACITY STUDY

SCOTT NIXON (Chair), University of Rhode Island

GEORGE DALRYMPLE, Everglades Research Group, Inc.

ROBERT DEYLE, Florida State University

WAYNE HUBER, Oregon State University

MARK PETERSON, University of Southern Mississippi

STEPHEN POLASKY, University of Minnesota

NORBERT PSUTY, Rutgers University, Cook Campus

MALCOLM RIVKIN, University of Maryland

DANIEL SHEER, Water Resources Management, Inc.

Staff

MORGAN GOPNIK, Study Director

JEFFREY JACOBS, Senior Program Officer

MARK GIBSON, Program Officer

MEGAN KELLY, Senior Project Assistant

NANCY CAPUTO, Senior Project Assistant

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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Acknowledgments

This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the NRC’s Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making its published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their review of this report: John Adams (University of Minnesota), David Godschalk (University of North Carolina), Lance Gunderson (Emory University), Steven McCutcheon (U.S. Environmental Protection Agency), James Porter (University of Georgia), and Kathleen Segerson (University of Connecticut).

Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations nor did they see the final draft of the report before its release. The review of this report was overseen by Dr. Robert Frosch (Harvard University). Appointed by the National Research Council, he was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×
This page in the original is blank.
Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×
Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×
Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

Summary

This brief interim report provides initial feedback from a committee of experts asked to review the Florida Keys Carrying Capacity Study (the Keys Study). The committee first reviewed the Scope of Work for the Keys Study (United States Army Corps of Engineers, 1998) and then attended a two-day public workshop in January 2001 during which the study team explained their goals and their progress to date. Based on this brief preliminary review, the committee concludes that it is feasible to create a semi-quantitative tool (referred to in the Keys Study as the “Carrying Capacity Analysis Model” or [CCAM] for assessing the broad impacts of alternative future development scenarios on important biological, environmental, social, and economic factors. To ensure that the final product of the Keys Study is useful and scientifically credible, the report provides several suggestions for CCAM designers at this time:

  • Place a greater emphasis on definition of concepts and agreement on desired outcomes

  • Ensure a higher level of coordination between the different modules that make up the CCAM

  • Make better use of the expert advisors who have been involved in the process and could offer valuable ongoing feedback

  • Set clear priorities, overall and within each module, to ensure that the most important elements are addressed first.

More detailed suggestions for completing the individual modules are also included. This report will be followed by a more thorough examination of the Draft CCAM once it is completed later this year.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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1
Introduction

PURPOSE OF THIS REPORT

For years policy makers at local and state levels have been working to achieve a balance between economic development, quality of life, and environmental protection in the Florida Keys. After a lengthy process of public debate and legal proceedings, Florida Administration Commission Rule 28.20.100 was issued in 1996, requiring the preparation of a “carrying capacity analysis . . . designed to determine the ability of the Florida Keys ecosystem, and the various segments thereof, to withstand all impacts of additional land development activities.” That ruling led to the initiation of the Florida Keys Carrying Capacity Study and its companion Carrying Capacity Analysis Model, which are sponsored by the U.S. Army Corps of Engineers (the Corps) and the Florida Department of Community Affairs and are being carried out by the contractor URS (formerly Dames and Moore). The Corps and the Florida Department of Community Affairs, in turn, requested that the National Academy of Sciences/National Research Council establish a committee to provide an authoritative, independent technical review of this ambitious effort.

The charge to this committee was as follows:

“[R]eview and evaluate the scientific methods, principles, and data that form the basis for the Florida Keys Carrying Capacity Study and the accompanying Carrying Capacity Analysis Model being developed by the State of Florida. The committee will assess the ability of the Keys Study to fulfill its stated goal of ‘determining the ability of the Florida Keys ecosystem to withstand all

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

impacts of additional land development activities,’ and the extent to which the conclusions were reached based on a sound scientific process.

Specifically the committee will review and comment on the following:

  • the overall design assumptions

  • the data used

  • the requirements, responses, limiting factors, and thresholds for study categories selected

  • the determination of how land development activities will affect study categories

  • the adequacy and reliability of the study as a basis for local and state land management and planning decisions.”

The Keys Study is moving forward on a strict and very rapid schedule. Pending its outcome, strict limits have been placed on further development in the Keys through a rate-of-growth ordinance. These limits and a strong public desire to move beyond the impasse toward a long-term solution provide strong motivations to move forward as quickly as possible without sacrificing the credibility of the end product.

To provide rapid feedback to the project managers the National Research Council agreed to provide this interim report. The report is based largely on presentations made by the contractor at a two-day workshop held in Key Largo, Florida, January 9–10, 2001 (referred to in this report as the January workshop), where the contractor described progress to date in designing the CCAM. The committee will prepare a second, more detailed report when the contractor presents a complete working version of the CCAM, scheduled for June 2001.

The Keys Study is an innovative endeavor, and the committee is unanimous in its appreciation of the ambitious vision it represents. The committee members are also very aware that our understanding of the details of the study is limited by our recent and relatively brief exposure to it. The committee also remains mindful that the study is a work in progress. Although various enhancements and mid-course corrections may already have been made by the time this report is received, the committee nevertheless believes that an independent assessment of progress to date will remain useful to the project’s sponsors and program managers. In some cases the observations and recommendations in this report echo those made publicly by participants at the January workshop. In all cases the comments contained in this report reflect a consensus of this committee, based on intensive discussions throughout the workshop and the following day and in subsequent correspondence.

KEYS STUDY PHILOSOPHY, TERMINOLOGY, AND OBJECTIVES

Before addressing the specifics of project management and the technical content of the CCAM, it is worth examining the Keys Study’s broader philosophy

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

and objectives. Although the following discussion focuses on the use of particular terms (such as “carrying capacity,” “thresholds,” and “model”), the committee believes that the inconsistent use of these terms reflects underlying conceptual challenges in the Keys Study, and the conflicting perspectives and needs of different end-users.

The term “carrying capacity” is not easy to define. The glossary in the scope of work for the Keys Study defines “carrying capacity” as “maximum population impacts an area can sustain over time with a given level of technology and societal preferences.” This definition is rooted in the concepts of regional planning (Godschalk, Parker, and Knoche, 1974) and implies that there are defined thresholds given certain assumptions. Under this view, carrying capacity is limited by a set of maximum impacts that can be tolerated—a question involving human preferences about the quality of the environment and nature of communities. These impacts can also be modified if suitable technologies exist and are purchased. Such an approach will be most useful to the Florida Department of Community Affairs and other planning entities that have been directed by Florida Executive Order 96-108 to “adhere to and implement the findings of a carrying capacity analysis as it relates to and affects the rate of growth and permit allocation in Monroe County.”

The scope of work also clearly states that “[t]he carrying capacity analysis shall consider aesthetic, socio-economic (including sustainable tourism), quality of life and community character issues, including the concentration of population, the amount of open space, diversity of habitats, and species richness.” These factors are important for residents and local leaders who care deeply about the impacts of alternative land development scenarios on the local economy, community character, and the environment.

On the other hand, the scope of work elsewhere explains that “[a] broad approach was chosen where elements of human society would be included as explicit variables in the modeling yet the value of protecting non-human species and the ecological system would establish the fundamental basis of the study” [emphasis added] and that the Keys Study will “determine the level of land development . . . that can be supported by a healthy, balanced, functioning ecosystem in the Florida Keys.” These goals reflect an attempt to apply the theoretical notion of ecological carrying capacity to assess relative environmental impacts.

Unfortunately there simply are no objective scientific criteria for determining “a healthy, balanced, functioning ecosystem . . .” Natural systems rarely exhibit quantifiable “thresholds” for species success and ecosystem functioning. In other words, there are no clear limits that separate healthy and non-healthy conditions. Whereas the habitat requirements for a few threatened and endangered species are reasonably well known, this is not the case for most components of the Keys ecosystem. Most evidence suggests that plants and animals respond to change in extremely complex ways, sometimes gradually and reversibly, sometimes with sudden non-linearities. For similar reasons, the terms

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

“indicator species” and “keystone species” do not have clear meanings, as discussed in Section 6 of this report.

Furthermore, both ecosystems and human communities are dynamic systems. The ability of an ecosystem to sustain viable populations shifts over time, in response to natural and human factors that vary over the short term (e.g., annual and decadal disturbances and cycles) and the long term (e.g., climate change). Community preferences also shift over time, as do technological alternatives for mitigating the impacts of human development. Thus, the notion of carrying capacity as the basis for determining limits for development depends on value judgments made by stakeholders about the desired state of the natural and built environments and will always be a moving target that must be regularly reassessed.

The use of the word “model” is itself problematic. Although the concept of a carrying capacity analysis model for the Florida Keys human and natural ecosystems is appealing, the construction of a precise mechanistic model that simulates all human and natural systems and their interactions, as suggested by the scope of work, is simply not possible within the current limits of funding, time, and basic knowledge. More realistic is the more modest goal of producing a useful planning tool that can be combined with other public policy efforts to help “determine the level of land development activities that will avoid (or at least minimize) further irreversible and/or adverse impacts to the Florida Keys ecosystem.” De-emphasizing the goal of creating a full numerical simulation model will also make it easier to incorporate less tangible, but critical, factors that affect the quality of life.

As a first step, the Keys Study should downplay the concept of producing a precise numerical “model” and focus instead on the production of a semi-quantitative “impact assessment tool” that can be used to help illustrate the consequences of various development scenarios on the environmental and social systems in the Keys. In keeping with this view, this report refers to the CCAM as an assessment tool, offering suggestions as to how the tool can be refined and focused in keeping with available knowledge and resources. The actual terminology to be used in the draft CCAM should be carefully considered by the design team.

Although the Keys Study must, of course, stay within the intent and spirit of the legal order that set it in motion, the sponsors and contractor will ultimately have to decide and agree on what can be meaningfully achieved. The contractor, the Corps, the Florida Department of Community Affairs, Monroe county managers, and other interested parties should acknowledge the existence of conceptual ambiguities and differing user needs, and continue to discuss realistic expectations for the Keys Study’s products, particularly the CCAM. Continued use of inconsistent definitions or reliance on an unrealistic picture of nature will make it difficult to achieve a common understanding of the goals for this vast and complex undertaking.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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2
Project Structure and Management

The committee finds that it was wise, and even necessary, to divide the CCAM into more manageable subsections or modules. The time constraints alone require such a breakdown, but the range of required technical expertise is also too great for any single team to cover. The companion to this decentralized approach is a need for detailed planning and frequent communication between the module teams. This kind of coordination appears to be missing. As a result, there were duplicated efforts (e.g., in water modeling), gaps in coverage (e.g., inadequate coverage of mangrove areas), and a serious lack of clarity about what inputs each module needed from the others and what outputs each was expected to provide. Seeing this kind of disconnect almost halfway through the life of the project is cause for concern and calls for immediate changes in project structure if a functional product is to be delivered by the June deadline. The various module-specific teams should be brought together as soon as possible to hammer out a roadmap detailing the needed inputs to and outputs from each module and precisely describing the connections and feedback between them. Frequent and regular contact (at least monthly and possibly weekly) should then be maintained to compare notes, discuss unforeseen difficulties, and amend the roadmap as needed. High-level planning and inter-module coordination should receive attention and resources from the study sponsors and the contractor on a par with the investment being made in each module. If it does not already exist, an appropriate task should be created under the Corps contract to cover coordination efforts.

The committee was impressed by the caliber and dedication of the large group of experts who attended the initial planning sessions and participated in the January workshop. These individuals represent an invaluable resource that has

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

not been used as thoroughly and effectively as it might have been. Although frequent large workshops may be impractical, an efficient and highly cost-effective approach might be for each module team to meet and/or hold conference calls regularly with small (2–4 person), subject-specific advisory groups who could offer technical input, criticism, and encouragement along the way. Of course, all experts will not agree on every issue; however, the broad discomfort expressed with basic aspects of the CCAM modules during the January workshop was surprising and reflected a lack of ongoing communication between the contractors and the expert advisors.

Due in part to the factors mentioned above, the rate of progress on the CCAM has been slower than will be needed to meet the ambitious timeline. The committee was not presented with a comprehensive picture of the level and distribution of resources for the project, so it is not possible to comment on this aspect. Some workshop participants suggested that the “task order” contractual arrangement between the contractor and the Corps may create a drag on progress by emphasizing sequential rather than parallel tasks. If this is the case, a serious effort should be made to initiate multiple, overlapping tasks, including some open-ended tasks that address overall coordination and long-range project planning. Whatever the solution, the pace will have to increase considerably, or the goals will have to be scaled down, if the project is to be completed in a satisfactory manner by the completion date. Alternatively, the Keys Study sponsors might consider amending the timeline.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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3
Development of the Assessment Tool

GENERAL COMMENTS

In addition to defining the inputs, outputs, and linkages between the individual modules (as discussed in the previous section) project managers should also immediately address: (1) the nature of the external inputs to the CCAM, from data sources or as specified in future scenarios; (2) the mechanisms and thresholds used in each module; and (3) the final outputs generated for the users. External data sources are discussed in greater detail in Section 6, and inputs from future scenarios in Section 5. The nature and acceptable format of all these inputs should be specified from the start and included in the coordination process called for in Section 2. The inner workings of each module are also discussed in Section 4. This section focuses on the final outputs from the assessment tool and on the determination of practical “thresholds.” As discussed in Section 1, clear, objective biological and social thresholds of viability rarely exist. Stakeholders, users, and technical experts should be consulted to help define thresholds and outputs that meet the project’s dual objectives for comprehensive planning and environmental impact assessment.

SPECIFICATION OF OUTPUTS

It is clear that the CCAM development team recognizes the importance of creating an assessment tool that addresses the diverse concerns of many stakeholders. The team has expended substantial energy consulting with the intended CCAM users, including Monroe county, its municipalities, and the concerned

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

public, through extensive interviews and public meetings. Although these efforts helped generate a list of topics of concern (included in the contractor’s User Needs Assessment Report, URS Corporation, 2000), participants in the January workshop were not shown a comprehensive, prioritized list of environmental and socio-economic variables for which assessments will be conducted and final outputs provided. The design of the entire CCAM should be driven by the environmental and socio-economic impacts of greatest concern to stakeholders, users, and technical experts, recognizing the need to prioritize in light of time and money constraints.

A limited set of appropriate outputs should be selected as needed for the likely applications of the assessment tool, including periodic reviews of comprehensive plans, proposed changes in land development regulations, assessments of specific large-scale changes in land use, permitting, enforcement, and adaptive management (see Section 5). Evaluation criteria should then be defined for the variables of greatest concern. Due to resource constraints, not every useful or desirable output can be included. Difficult choices must be made by the design team, with input from expert advisors and stakeholders. (The emphasis on using a geographic information system base throughout the CCAM will facilitate the output process and is one excellent feature of the current plan.) It is urgent that output specifications be defined promptly to ensure that each module and the overall project is properly designed to meet user needs. The results of this exercise should also be fed directly into the module coordination process discussed in Section 2 to ensure that each module design team knows what it is responsible for producing.

CREATING A FUNCTIONAL DEFINITION OF CARRYING CAPACITY THRESHOLDS

As discussed in Section 1, the current design of the CCAM may not achieve the objectives of all end-users. In particular, the Florida Department of Community Affairs and Monroe county planners must be able to determine the extent of additional development that can be supported by the ecological and human support systems of the Keys. The CCAM currently generates impact evaluations but does not explicitly determine whether carrying capacity thresholds will be exceeded under alternative land development scenarios.

Although it is not feasible to accurately define ecological thresholds for all species and ecosystems in the Keys (due to limitations in data and understanding or the inherent complexity of nature), it is still possible to meet the needs of potential users. To do so, however, will require a shift in how the CCAM is conceptualized.

As described at the January workshop, outputs from the CCAM assessment tool will consist of an array of environmental and socio-economic parameters, the values of which are presented on simplified ordinal impact scales, such as high, medium, and low or red, yellow, and green. The module designers would assign

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

these values based on their best professional judgment. This vision will not provide state agencies or local planners with clear answers about when critical thresholds have been exceeded, as required by Administration Commission Rule 28.20.100 and Executive Order 96-108. This approach will also produce an insensitive assessment tool, offering users little information about the relative impacts of alternative land development scenarios.

This committee suggests consideration of an alternative approach to designing the CCAM, in which users and experts agree on thresholds for specific evaluation criteria (similar to the process suggested in NRC, 1995). These consensus thresholds can then be used to exclude land development scenarios from further consideration if they pose significant threats to environmental or community integrity. At least three kinds of critical thresholds might exist:

  1. externally mandated thresholds, such as federal water-quality standards, state hurricane evacuation clearance times, or legal requirements of the federal Endangered Species Act;

  2. thresholds for environmental parameters, which if exceeded would pose a significant threat to the long-term survival of individual species or biological communities in the Keys ecosystems, based on the best professional judgment of technical experts;

  3. thresholds for selected socio-economic measures, which if exceeded would significantly degrade the quality of life in the Keys, based on a consensus of representative residents.

These thresholds could then be used, not to define the maximum human population that could be sustained but to assess how specific changes in land development affect the survival of species or biological communities, compliance with regulatory standards, and quality of life measures. Any development scenario (whether based on changes to comprehensive plans, land development regulations, or specific permits) whose impacts would exceed one of the thresholds would be judged as likely to exceed the human and/or biological carrying capacity of the Keys. An alternative that does not exceed any of the exclusionary criteria can be further evaluated to minimize harmful impacts and maximize positive impacts based on a broader range of user-defined evaluation criteria included in the assessment tool.

Under this approach CCAM outputs could use one color (e.g., red) to quickly indicate values that exceed a critical threshold. For some simple, well-defined parameters, such as coliform levels in recreational waters, a simple green/red, or okay/not okay scale may be sufficient, if not very informative. Most parameters, however, would be better presented on some kind of ordinal scale with many levels, depending on the range of variation of the parameter and the levels at which significant biological or quality-of-life impacts might occur. The scales would need to be developed with the advice of technical experts and users.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

4
Technical Content of the Assessment Tool

CROSS-CUTTING ISSUES

Each of the technical modules that comprise the CCAM is discussed in detail later in this section. In assembling these comments it became clear that similar issues were raised for many of the modules. By first understanding and addressing these cross-cutting issues, progress can be made in many areas.

  1. Inputs and outputs—Immediate and clear decisions should be made about exactly what inputs and outputs are needed for each module and for the CCAM as a whole. This problem was discussed in greater detail in Section 2, but it bears repeating.

  2. Setting priorities—Creation of an all-encompassing assessment tool such as the CCAM would be a challenging undertaking under any circumstances: The existing severe limitations on time and money make it an even greater challenge. Each module should, before proceeding any further, have clear priorities for what processes and subsystems will be included and at what level of detail. These should be driven by the desired outputs from the entire assessment tool. Technical experts (including the module designers, the outside experts, and this committee!) appreciate all the complexities of the human and natural systems being explored and are reluctant to oversimplify. For the purposes of the CCAM, however, it will be necessary to focus on a subset of primary, driving mechanisms and ensure that these are accurately modeled.

  3. Data quality—CCAM designers should be selective about the data sets used. Once decisions are made about essential inputs and outputs, and then about

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

which mechanisms and processes will be included, it should be easier to determine which data sets are most critical. Appropriate quality assurance/quality control (QA/QC) should be performed for every data set used in module calculations. The contractor should ensure that all data used are reviewed for reasonableness and their authenticity and range documented to the best degree possible.

  1. Definition of terms—In Section 1, this report discussed the ambiguities inherent in such terms as “carrying capacity” and “thresholds.” In the modules, similar difficulties occur with the use of terms such as “keystone species” and “indicator species.” Project designers should clearly define, or avoid, potentially ambiguous concepts. The expert advisors might be helpful in this task.

  2. Use of expert opinion—As discussed in Section 2, for many important endpoints (such as the minimum habitat required to sustain a given species), quantitative measures have not been or cannot be defined. In these cases it will be necessary to rely on the consensus of an appropriate group of experts or relevant stakeholders. This kind of consensus judgement is preferable to an unreliable, inexact, or otherwise inappropriate “objective” measure.

  3. Spatial and temporal scales—Consideration of the spatial and temporal scales in and between modules is critical. Time- and space-averaged quantities will not always reveal critical information. For example, the nearly instantaneous effect of a heavy rainfall event on water quality and public bathing in the halo zone may be a significant output. Conversely, the slow rate of sea-level rise should be examined as an output of the dynamic nature of coastline habitats that will undergo spatial shifts along the edges of the Keys, especially the lower-lying middle Keys. Spatially, the near-shore distribution of propeller scars, boat groundings, and marina impacts may be of most importance because of the greater likelihood of thresholds being achieved, although there are certainly many human impacts farther offshore.

  4. Uncertainty and variability—Every data set and numerical output that is part of the CCAM should include some measure of its variability. Variability can often be indicated by customary measures such as standard deviations, coefficients of variation, quantiles (e.g., 10 percent and 90 percent values), ranges, or frequency histograms. This kind of statistical variability is just one source of uncertainty in the output. Other sources of uncertainty include lack of complete understanding of the systems being modeled, modeling simplifications, scale issues (e.g., application of data collected at a small scale to a much large study area), non-linearities that affect scaling, changes that occur between the time of original measurements and the time of application, and incorporation of unquantifiable factors such as public attitudes. End-users should be clearly informed about the different levels of uncertainty in the outputs—even when these values cannot be easily quantified—and be advised of the implications of these uncertainties for assessing alternative policies, regulations, or actions. Sensitivity analyses should be performed on all outputs when the draft CCAM is

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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complete. These analyses will provide guidance about which input variables most influence the ultimate outputs and therefore warrant the greatest effort in ensuring their reliability. At the same time, sensitivity analyses will aid in selecting the critical processes to be included in the modules.

  1. Future updates—Section 6 discusses the benefits that could be realized by maintaining and updating the CCAM over the coming years. Although this decision will probably not be made until later, a small effort now can make a huge difference in facilitating later updates. Each module should identify key data sets and other factors that are likely to change over time and processes that are likely to become better understood. Documentation should then include specific recommendations and instructions aimed at future maintenance and improvement.

The suggestions above are of high priority and apply to all the modules. They are not repeated in the analysis of each module that follows, although specific examples are pointed out in some sections. The following sections are intended primarily for those directly involved in module development. Thus these comments include more terminology and a greater level of detail than previous sections.

SOCIO-ECONOMIC/LAND USE/ HUMAN INFRASTRUCTURE MODULE

This module plays three critical roles in the CCAM.

  1. It is the interface through which alternative plan amendments, land development regulations, and other scenarios are input into the assessment tool.

  2. It must produce appropriate outputs, such as land use changes and population projections, to be used as inputs to the other modules in evaluating impacts on natural systems.

  3. It must provide a range of important performance-measure outputs of its own.

All of these functions will need to be accomplished successfully if the overall carrying capacity study is to be successful. The module, as described and presented by the project team, is not now sufficiently developed to accomplish these crucial tasks.

As with all the modules, many uncertainties remain concerning inputs and outputs. In addition, this module has not yet developed a detailed approach for delivering useful socio-economic, quality-of-life, community character performance measures and other important issues. The project team also needs to establish a more realistic portrait of where future development is likely to occur and what patterns that development may take. As it stands, the module has a

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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narrow focus on development that excludes redevelopment potential and the influence of land development regulations. This module will need to provide information about what development or redevelopment activities occur and where these activities occur, at a scale and in a format consistent with the approaches taken by the terrestrial, marine, and water modules.

The current plan to provide output as acres of development in general categories (as population and dwellings for 29 area units) does not appear consistent with the input needs of the other modules. For example, fragmentation of habitat, which depends on the location and not just the total acreage of development, is important to the terrestrial ecosystems and species module. In determining wastewater volume and contaminants it is important to know the types of development that occur—fish processing plants versus shopping centers, for example—rather than aggregate categories. It is also important to account for land development regulations that govern the quantity and quality of stormwater generated, such as limits on total impervious surface or design and performance standards for stormwater detention, retention, or treatment.

The socio-economics, land use, and human infrastructure module must be able to link population growth estimates (both in number, type, and location) to resultant plausible land use scenarios in order to produce GIS-based maps of appropriate quantities, both for use as final outputs and as input to the other modules. It is highly unlikely that population and economic growth will be concentrated on undeveloped, privately owned, upland sites. With 70 percent of the Keys’ land already in public ownership, and most of the residual private property developed in some fashion, pristine available sites are apparently quite limited despite an inventory of unbuilt platted lots. This is especially true in considering demand for non-residential space (i.e., commercial, service, or hotel). Construction of non-residential facilities has been greatly constrained, perhaps even more so than for residential units, during the Rate of Growth Ordinance period. Instead, the main focus of future development, whether limited by growth restrictions or simply in response to market demands, is likely to be on currently developed sites already disturbed beyond their pristine state.

Some existing sites may be candidates for redevelopment, in other words, the replacement of old or obsolete structures by new uses at contemporary standards of construction. Other sites may be underutilized, that is, occupied by commercial or residential structures built well below current zoning potential, to which new uses at higher densities will be attracted. Given the physical configuration of the Keys and the evolution of development there over more than 150 years, such conclusions appear inevitable. The very fact that Route 1 is the only major road and its adjacent lands form the only corridor providing easy accessibility for commercial and other non-residential uses (including public facilities such as schools and libraries) drives these conclusions. The module design team should identify sites that are the most realistic redevelopment targets and then design

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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several redevelopment scenarios to assess the impacts of build-out to maximum allowable densities and intensities on the human and natural environments.

To do so this module will need to accept input parameters that reflect potential amendments to land development regulations or changes to comprehensive plans and future land use maps. These sorts of changes will alter the impacts of development and redevelopment on such output measures as environmental quality, socio-economic conditions, and quality of life. Based on the January workshop presentations, it appears that the study team is treating potential development as an “on/off” switch. The team seemed to include only new growth (i.e., new dwelling units, square feet of retail, acres of commercial) and the extent to which it “disturbs” land, thereby presenting an overly simplistic view of ecosystem impacts and effectively ignoring socio-economic and quality-of-life impacts.

Different comprehensive plan policies and land development regulations can produce very different levels and kinds of disturbance. For example, a clustered, zero-lot-line project, with stormwater source controls and substantial open space, may be more environmentally benign than a subdivision on conventional quarter acre lots with engineered stormwater retention or detention systems. Developments with the same numbers of dwelling units can have significantly different occupancy rates and can attract substantially different types of residents whose impacts on the natural environment and on public facilities and infrastructure may also be significantly different. Thus the module should be able to account for an array of land development regulation alternatives and the variable impacts that result.

The project team should consider the use of a regional economics model capable of providing information on different sectors of the economy. The current aggregate approach overlooks differences in environmental and human impacts that arise from different types of economic activity. Looking in more detail at various sectors will allow the project team a more accurate picture of the types of development pressure likely to face Monroe county and the likely environmental impacts that may result. The use of a more detailed regional economics model also allows projection of employment and income patterns, important economic performance measures in their own right. Given the time and budget constraints, the team should adopt an existing regional economic model, supplied with Monroe county data and adapted to fit local conditions.

Tourism is the principal economic activity in Monroe county and should be an integral part of the CCAM. According to the U.S. Census’s County Business Patterns (1998), more than 55 percent of the employment in the county was in two tourism-oriented sectors: (1) accommodations and food service and (2) retail. It is appropriate that projections of future tourist levels are being included in estimates of functional population, but this is not enough: Land use, facility character, water access requirements, and traffic impacts of tourism should also be examined. Tourism experts should be enlisted to assist in estimating the effects of alternative land development scenarios on the number and type of

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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tourists likely to be attracted to Monroe county. Attention should also be given to identifying affordable housing options for tourism industry support staff. Based on the geography of the Keys, long-distance commuting or labor shortages are not viable options in this sector.

The existing market analysis framework assumes that housing demand is fixed and exogenous, instead of modeling the demand as a function of housing prices. Housing prices are determined by considerations of supply and demand, with prices rising and falling to equate supply and demand. Ignoring price effects in the housing market is a serious deficiency. Monroe county currently has the highest median house price of any county in Florida. Because of continuing pressure on the housing market and concerns over affordable housing, projections of land and housing prices should be an important performance measure. In the context of the Keys, where physical and regulatory constraints largely limit the supply of developable land, changes in demand essentially translate into changes in price.

One essential Keys Study goal is to assess the impacts of alternative land development scenarios on the local economy and community. To date, factors other than fiscal impact analysis, land use, and population projections have been largely ignored, although the carrying capacity study was charged with considering socio-economic, quality-of-life, and community character issues. The range of expertise on the project team (including the expert advisors) should be expanded to include individuals conversant with aesthetic, socio-economic, quality-of-life, and community character issues and those knowledgeable about relevant design and performance standards that may be incorporated in future land development regulations.

WATER AND WASTEWATER MODULE

The original scope of work required the Keys Study to “describe site specific interactions between geology, surface water, coastal water, land use, nutrients, pollutants, runoff, erosion, and vessels.” This is a tall order, and central to achieving it will be understanding the nature of water flows throughout the Keys. In the general area of water systems modeling, the CCAM identifies three primary subareas: stormwater, wastewater, and receiving water. These are further subdivided in the contractor’s water-modeling flow chart, but it is these three subareas that are the focus of the discussion that follows. The stormwater submodule is farthest along toward completion, followed by the wastewater submodule. Tracking water-quality constituents from their generation on land to their fate in near-shore receiving waters is a very complicated process. In particular, the receiving-water modeling effort has the potential for massive complexity and this element remained purely conceptual at the time of the January workshop. Given the pressing time constraints, the contractor should make every effort to identify essential components that cannot be omitted or simplified and

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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focus resources on those components. Establishment of clear aquatic ecological indicators and the performance of sensitivity analyses on important parameters and forcing functions will help guide the effort.

The following comments are to a significant degree based as much on what is planned as on what has been accomplished to date. In addition to participating in the January workshop, the committee has drawn some inferences based on verbal evaluations of the water module made by the expert advisors who attended the January workshop.

General Comments

Overall, the committee finds that the stormwater modeling effort is on track. The contractor is using a simplified runoff prediction method based on daily rainfall records and runoff coefficients (a “spreadsheet” approach). This approach can be justified by the lack of a need for surface flow routing (which would require shorter time step computations) and the current goal of evaluating only those receiving-water-quality indicators that respond over a long time period. However, the committee notes that hourly or even 15-minute runoff estimates (consistent with available rainfall data) could be performed by the same spreadsheet method if necessary and could be helpful in analyzing certain kinds of scenarios.

The linkage between this module and land-use descriptions is consistent with the need for data on imperviousness and other parameters that influence runoff. Use of event mean concentrations is a reasonable way to develop water-quality loads (WEF and ASCE, 1998; NRC, 2000). The committee understands that event mean concentration data are not currently available for the Keys, but the contractor should investigate the transferability of urban data for South Florida, especially for impervious surfaces. The limerock and sand stratigraphy of the Keys make it harder to evaluate the impact of some stormwater best management practices, since studies elsewhere reflect the mitigating effects of greater depths and different types of soil. (The level of uncertainty introduced with any such extrapolation should also be assessed.)

Wastewater loadings can reasonably be based on documented effluent quality of the treatment devices currently in use in the Keys (NRC, 2000), including cesspools, septic tanks, aerobic septic systems, on-site wastewater nutrient reduction systems, and wastewater treatment plants, as proposed by the contractor, with attention to the quality and variability of the different data sets. Although gaps exist, a good effort has been made at defining the extent of each type of disposal system in the Keys and at assessing long-term plans for upgrading inferior systems. Nevertheless, the quality of the effluent that reaches the coast following seepage from residential systems or discharge from shallow (60–90 ft) boreholes for small wastewater treatment plants is unknown. The ultimate fate of wastewater injected into shallow or deep wells is also unknown. If long-term

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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solutions for the disposal of treated wastewater focus on injection wells, it will be important to know whether upward migration of the effluent plumes will occur. Finally, wastewater loadings should account for the transient nature of population in the Keys, including the relatively recent appearance of large cruise ships in Key West. Initial estimates should be made of wastewater loadings caused by the influx of persons from such ships to determine whether these will be significant and to determine the impact of such short-term loading peaks on the performance of the Key West wastewater treatment plant.

Detailed Comments

1. It is unclear what final parameters will be generated to evaluate the Florida Keys carrying capacity based on aquatic water quality. The focus area seems to be the halo zone, 50-100 m of salt water adjacent to the islands’ beaches (defined at the January workshop as water approximately 1 m deep or less). Specific aquatic end points mentioned were seagrass coverage in the halo zone, the extent and location of benthic communities, coral reef status, the species associated with the previous three communities, and water clarity, perhaps including water clarity in finger canals.

The method for evaluating receiving-water quality in the halo zone is still under development. The outline as presented at the workshop was to drive a steady-state receiving-water-quality model using residual near-shore currents based on the Corps’ Florida Bay model or some alternative Florida Keys circulation model yet to be defined. Steady-state modeling was justified by the response of seagrass—assumed to be the primary aquatic endpoint—which occurs over a period of many months, making short-term variations in loadings and currents unimportant. This assumption may be correct for seagrass, but concerns remain regarding the necessary timescales. Some questions include the following:

  • To evaluate seagrass growth, what water-quality parameters are needed, both in the receiving water and from stormwater and wastewater runoff estimates? If dissolved inorganic nitrogen is to be used in a receiving-water-quality model, can the necessary loadings be provided to drive the model? The contractors should consider the successful seagrass modeling performed in Tampa Bay.

  • What parameters are required to estimate water clarity?

  • Can receiving-water quality be estimated solely on the basis of long-term loadings, allowing for use of a steady-state model, or is there also a need for short-term modeling for bacteria, pathogens, or biological oxygen demand (BOD)? For instance, water-quality standards for coliform bacteria exist for Class III marine waters. These standards might serve as appropriate performance measures in the CCAM (§62-302.503 Florida Administrative Code). Other standards for Class III marine waters, such

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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as those for biological integrity, dissolved oxygen, BOD, pH, transparency, and turbidity should also be considered possible performance measures and may be appropriate inputs to the marine ecosystem module. It may be appropriate to incorporate the prohibitions that result from designation of most of the waters surrounding the Keys as outstanding Florida waters (§62-4, Florida Administrative Code).

  • Is the water quality in finger canals an important CCAM output? If so, a different level of receiving-water model will be needed.

  • Although the health of coral reefs was identified as an issue of concern in the scope of work, the modeling of reef response to anthropogenic forcing functions is very complex. Will it be possible to do this quantitatively within current project constraints? If not, how will this endpoint be evaluated?

  • What are the implications for the Keys of possible long-term changes in the water quality of Florida Bay, and will the CCAM be able to incorporate such changes?

Consideration of these questions is important to guide further development of this module and allocate resources wisely. Appropriate land-side loadings and temporal and spatial definitions will need to be resolved quickly to meet the needs of receiving-water modeling. Far-field forcing functions (such as regional current models) should also be better linked to the near-shore modeling efforts.

2. The water systems experts must know what water-quality parameters (such as receiving-water concentrations) will be needed to evaluate the status of various important aquatic species.

3. There is an urgent need to provide quality assurance/quality control on the data used in the water modules. For example, in the wastewater module the effluent quality predictions for BOD, Total Suspended Solids, Total Nitrogen, and Total Phosphorous presented by the contractor were probably overly optimistic, based on the immediate feedback from the experts.

4. Related to the issue of quality assurance/quality control are those of variability and uncertainty. The contractor should continue to seek out the best available data sources for items such as stormwater event mean concentrations or wastewater treatment performance measures. The use of these data, however, must be qualified by their inherent variability. Variability can be assessed by using several sources of stormwater quality data in South Florida and variations over time at individual sites. A realistic range of effluent quality should also be employed for evaluation of wastewater discharges.

5. Because the water calculations are driven by weather, the nature of the long-term weather patterns input to the CCAM will strongly influence the water-quality endpoints. For instance, a wet year generally provides higher loadings than a dry year. With this in mind, the basis of the weather scenarios should be clarified. Use of a number of representative conditions (e.g., dry, average, or wet

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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for stormwater modeling and calm, average, or windy for circulation modeling) is one option for evaluating the impact of climatic variations. Continuous hydrological modeling (i.e., a rainfall and meteorological time series lasting over a period of years) is another, more complex option that could be used to ensure realistic variability. However it is achieved, the water module should incorporate variations in climatic conditions and should quantify these variations and their impacts on module outputs.

TERRESTRIAL ECOSYSTEMS AND SPECIES MODULE

This module, like most, was in a very early stage of development at the time of the workshop. The module designers were unable to answer many questions, because they had not yet considered all the important issues. The largest efforts so far seem to have been made in reducing the list of species to be considered in evaluating the impacts of development. As of January 2001 the list had been reduced from an initial 128 to 17 and was reduced further over the course of the workshop. The species chosen include federally listed endangered species (both threatened and endangered), a rare-plant community complex, a suite of fruit-producing species (incorrectly described as keystone species), some species that are dependent on fire and pineland, and several species that are good indicators of hardwood hammock habitat.

This module cannot and was perhaps not intended to function as an ecological population dynamics model that might typically be used to quantify biological carrying capacity. The module was also not intended to be a dynamic habitat or ecosystem function model. Instead, it provides a very simplified measure of future habitat losses and fragmentation. The processes, database, and methods described at the January workshop will produce an assessment tool that provides a basic illustration of probable degrees of impact from future development.

Other modules may require maps of upland and wetland habitat distribution. Such maps are the basis for all impact evaluations planned for this module, however it is not clear that up-to-date and professionally agreed coverage maps for these habitats currently exist. It also appeared that the actual geographic distributions for some of the species being examined are in dispute (e.g., the lower Keys marsh rabbit). For some species (e.g., the white-crowned pigeon) information for the lower Florida Keys will be needed in addition to the information being relied upon for the upper Keys. Such information will have to be obtained and integrated immediately if these species are to be included.

To date, no habitat- or ecosystem-level outputs based on physical factors or processes have been developed. The design team agreed that any additional losses of hammock or pineland would be unacceptable for many of the chosen indicator species or groups (e.g., Schaus’s butterfly, wooly croton, rare plants, tree snails, wood rat, Key deer, tree cactus, forest birds). The team stopped short of concluding that mapping additional habitat fragmentation or loss of acreage in

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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pinelands or hammocks would in itself serve as an effective output to identify development impacts. This is a simple and obvious addition to this module’s outputs, but it requires input from the socio-economic module that is spatially explicit about where land use changes will occur.

As mentioned above with respect to pinelands and hammocks, the contractor expressed an intention to look more closely at habitats or ecosystems, but no specific proposal was presented for review. Of particular concern at this time is the lack of any clear plan for reviewing the distribution, status, or impacts of development on wetlands. Some indirect evaluation would be derived from looking at single species that depend on freshwater wetlands, such as the mud turtle. Some level of wetland response may also be derived from the assessment of red mangrove impacts. However, no habitat level assessment of tidal wetlands is currently included in the module. Wetlands compose nearly 60 percent of the study area and have a history of direct and secondary cumulative adverse impacts from development. The wetlands areas deserve a much higher profile and level of evaluation than allocated to date. Different parts of this evaluation may involve the water, terrestrial, and marine modules. Some level of gradient analysis of water quality in tidal wetlands should be included as an output from the CCAM.

In the case of the Key deer the opinions of the module design team appear to be at odds with accepted scientific information and opinion. For example, workshop participants were told that the information necessary to conduct a population viability analysis was not available for any of the team’s chosen species, however a thorough population viability analysis was performed for the Key deer in 1990 (Seal et al., 1990). The module design team should take advantage of the extensive information available on this well-studied endangered species. The outside expert advisors could be very helpful with this task. Doing a top-notch job with this high-visibility species would add a good deal of credibility to the overall effort.

The module-design team had previously agreed upon using geographic, spatially explicit mapping of habitat loss and fragmentation as the means for evaluating various development scenarios. To date, the impact analyses have been made by selecting specific habitat patch sizes below which a given species will no longer inhabit that patch. The outputs produced are summary statistical tables and color-coded maps indicating the number of patches from which a species is eliminated due to a particular development scenario. The scenarios tested to date simulate losses of habitat caused by additional upland development. The rules that determine minimum patch sizes needed are generally well thought out, easy to understand, and easy to measure, however these rules have not been fully developed or accepted by a consensus of experts. Additional consultation and review will be needed to ensure the credibility of the outputs. It is essential, as noted above, that the output from the socio-economic and land use module provide spatially explicit data about where land use change will occur.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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Beyond the basic rule on patch size described above there is some concern that within-patch variability has been ignored. All patches of a given size are not the same from a species point of view. Consideration of inter-patch variability for such features as time since last fire, presence of specific host species, or sources of drinking water could significantly and easily improve the module output. By including information on conditions immediately surrounding each patch (e.g., type of development, availability of drinking water, prevailing wind direction) the outputs can be made more detailed with relatively little effort.

MARINE ECOSYSTEMS AND SPECIES MODULE

This module was also in a very preliminary stage of development at the January workshop. The contractor presented some interesting concepts, such as the approach to assessing the impacts of boat scarring on seagrass beds, but many elements of the module were still undeveloped. As discussed in Section 2, lack of sufficient coordination between modules has been a major barrier to progress. For example, the marine and water modules will need to reach an immediate decision about the modeling of Florida Bay waters and their impacts on Keys water quality. Much of the effort to date in the marine module has been spent on gathering useable data sets, anticipating the data that may be generated by other modules, and exploring other potentially available data.

Three main metrics were identified for marine ecosystems: seagrass cover, water clarity, and contaminant loads. Because the data are relatively sparse and the diversity of marine fauna is high, the module design team decided to focus on a process-oriented approach rather than a species-specific approach as used in the terrestrial module.

Although seagrasses play a central role in determining the overall health of the marine ecosystem under the proposed approach, the maps of species-specific seagrass distribution were not well developed. Because all seagrasses are not the same (in terms of growth patterns, nutrient requirements, recovery time after prop scarring), further work will be necessary to map the distribution of seagrasses around the Keys.

Up until now almost no effort has been made to understand either the impacts of fishing on marine ecosystems or the impacts on fish populations of other activities. There was some reference to gathering data on the increase in marinas and boats, but it was unclear how such data would be used. If such information is desired, it should be produced as an output from the socio-economic and land use module. With little time remaining, many important issues remain to be investigated: collisions with manatees, fishing pressure per boat, size of boats (which relates probably non-linearly to the number of fishers per boat), and reef damage due to recreational diving, boat anchors, and removal of upper level predators. These constitute real impacts to the health of the Florida Keys.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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Because the marine module design team’s approach so far is spatially explicit and does not consider temporal aspects, the assessment tool will be able to provide only a basic visualization of relative degrees of impact and fragmentation from future development, and only for a limited marine community. For example, the current approach would produce a tool that could not examine the impacts of such short-term events as sediment pulses from storms on communities of concern at some vital time in organism or community development. It would also be unable to assess synergistic or cumulative issues. Furthermore, the spatial arrangement of impacts (mangroves to seagrass to inshore patch reefs to offshore reefs) should be examined, given the juxtaposition of these important habitat types in space and the documented connections between these important habitats and proper nursery function throughout the Keys (e.g., for snappers, grunts, and groupers).

Finally, the marine module does not currently look at species on the Federal Endangered Species List or the Official Lists of Florida’s Endangered Species and Species of Special Concern, such as the manatee, crocodile, mangrove rivulus, and numerous marine turtles. It also does not consider important intertidal marine habitats, like mangroves. The inclusion of these federal- and state-protected species in this module is vital and will provide important performance measures for the carrying-capacity analyses.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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5
Applications of the Assessment Tool

BASIC REQUIREMENTS

If properly designed, implemented, and maintained, the CCAM assessment tool could be extremely useful for a number of applications. Foremost, the tool is intended to help evaluate proposed comprehensive plan amendments as well as the regulations designed to implement those plans. This is evident from the list of future scenarios developed for testing, some of which are described in terms of land use patterns (as for a comprehensive plan) and some of which are described in terms of regulatory policy (e.g., no more than 10 permits per year in Islamorada). Although the project team described how to input and thus assess a particular snapshot of land use, the committee saw no obvious input mechanism for evaluating regulatory policies.

To serve its main purpose, the CCAM must be capable of accepting inputs either as an end-of-period land use picture or as a set of regulatory policies designed to achieve such land uses. In other words, it must accommodate spatially explicit build-out scenarios based on future land use plans, zoning regulations, and other land development regulations that govern density and intensity of land use. From these scenario characteristics the CCAM should generate the parameters needed as inputs to the ecosystem, water-quality, and socio-economic and land use modules. The CCAM should be capable of assigning new development and redevelopment to specific land parcels to generate spatially explicit outputs that represent development impacts.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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ADDITIONAL OPPORTUNITIES

The assessment tool could have several very valuable additional applications. Although there will probably not be enough time to develop all of these applications immediately, it will be helpful to keep them in mind during the design phase in order to facilitate their addition at a later date. To ensure that actual development on the ground is consistent with amended comprehensive plans or land development regulations, the CCAM should be able to serve two additional functions: evaluation of permit applications and adaptive management. Once the comprehensive plans are amended and supporting regulations developed based on the results of the Keys Study, the permit limitations and conditions implied by those regulations can be incorporated into the assessment tool. The CCAM could then automate many of the labor-intensive functions required for evaluation of permits, resulting in reduced administrative costs and more consistent evaluations. This is an extension of the role currently envisioned for the routine planning tool, a still undeveloped component of the CCAM that, as described, would only make the underlying data in the CCAM available for use in the evaluation of permits.

To implement adaptive management it is important to know whether local comprehensive plans and their implementing regulations are having the desired effect over time. Because of the unpredictable influence of natural variables, it is necessary to use models to assess the extent to which actual impacts are consistent with original expectations. If the CCAM databases are updated to include newly permitted development, then the predicted impacts can be compared to the results of actual monitoring. Assuming that the original CCAM went through a rigorous validation process, deviations between predicted and observed conditions could uncover ongoing violations of environmental permits or indicate that regulations are not achieving what was intended. In either case the CCAM could be revised as appropriate and then used to develop improved adaptive-management actions.

SCENARIO DEVELOPMENT

Scenario testing serves several functions in the CCAM, and as many tests as possible should be run. Such testing will provide sensitivity analyses and help to identify errors by uncovering anomalous results. In consultation with the expert advisors, a battery of test scenarios should be designed for the sole purpose of exploring the performance and limitations of the assessment tool.

Of course, scenario testing is also at the heart of the goal of the Keys Study. By examining a range of possible futures for population growth, economic and land development, and environmental management in the Keys, planners can make meaningful, well-informed choices about the future. The alternatives currently being considered (as listed in the Project Strategy Outline, Dames & Moore,

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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2000a) are described in very different ways. Although some are described in terms of land use patterns, others depict potential land development regulations designed to manage future development. It is not at all clear how the CCAM will handle such scenarios as input, nor is it clear how land development regulations will be converted into the kinds of spatially explicit inputs that will be needed by the other modules to determine the impacts of alternative scenarios. As mentioned above, efforts will be required either to develop an input format for such regulations or to craft reasonable protocols for automatically or manually converting such scenarios into spatially explicit data suitable for analysis.

Evaluation of one or more hurricane disaster scenarios can provide useful information to state and local land use planners about the relative vulnerability of different future development patterns (Deyle et al., 1998). It is much more difficult, however, to develop hurricane impact scenarios for biological communities that will provide useful information for the evaluation of planning and land use alternatives. While a comprehensive evaluation of the full range of possible hurricane scenarios is not possible under current time and budget constraints, it may be feasible to assess one or more scenarios that simulate the likely damage to the built environment from a Category 3 or Category 4 hurricane. Local disaster mitigation policies and programs can help lessen the impacts of hurricanes of this magnitude, while catastrophic storms (Category 5) generally are viewed as “acts of God” beyond feasible mitigation (Godschalk, Brower, and Beatley, 1989). Such a vulnerability assessment should be possible using existing land use and property data available from county and municipal agencies in the Keys and the TAOS software available from the Florida Department of Community Affairs. TAOS can be used to estimate damage from storm surge, wave height, maximum sustained surface winds, and inland flooding (Watson, 1995; Florida Department of Community Affairs, 1998). It also may be worthwhile to explore the effect of sea-level rise on storm surge levels 25 and 50 years into the future to assess the altered vulnerability of the built environment.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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6
Follow-up for the Assessment Tool

Given the significant investment being made in this innovative tool it would be a shame to use it only in the next round of comprehensive plan amendments. However, any future use of the CCAM, including the additional applications described above, will be possible only if the CCAM is maintained. Although the study team indicated that discussions about the CCAM’s future have been initiated, and the scope of work refers to development of a fiscal and administrative framework for this purpose, this issue should be given substantially more attention, now, during the design phase. Suitable provisions should be made in each module to ensure that future updates, revisions, or enhancements are possible. Changes will certainly occur in the development patterns and overall economy of the Keys. Changes may also occur in nature (such as sea-level change), in local culture, or in our fundamental understanding of human and ecological systems.

The ultimate creation of a continuing implementation mechanism will depend on future decisions by the Florida Department of Community Affairs, the Army Corps of Engineers, and Monroe County and is clearly beyond the scope of the current contract. Nevertheless, one relatively simple task under this contract should be to provide a blueprint for such implementation while the contractor and subcontractors are still familiar with the inner workings of the CCAM. The blueprint should include at least the following elements:

  1. Suggestions for plausible organizational mechanisms for maintaining and updating the assessment tool (for example, within a state or county government agency or a university);

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×
  1. A description of the number and kinds of staff required;

  2. An estimate of the initial and subsequent annual budgets required, along with any special logistical and equipment needs.

Based on considerable experience with comparable large projects, the committee recommends that design of a detailed implementation program be one output of the present effort.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

7
Conclusion

The Florida Keys Carrying Capacity Study is an ambitious effort, and this committee fully appreciates the technical and policy challenges facing the study team and sponsors. The challenge of creating a comprehensive, flexible, and reliable assessment tool is compounded by a highly charged political atmosphere surrounding land development and environmental issues in the Keys. The study team is to be commended for its efforts to date and the many areas where progress has been made in the Carrying Capacity Analysis Model and the overall study.

The committee notes that this brief interim report is based primarily on presentations made during a two-day workshop that attempted to describe a major activity still in progress. The committee appreciates the cooperation and explanations offered by the study team and recognizes that its exposure to the assessment tool has been limited. The comments and advice provided are offered in a spirit of constructive criticism with the understanding that many changes and improvements to the assessment tool may already have been made since the workshop.

The major concerns raised by the committee at this time, along with some suggested remedies, are summarized below. Many more detailed observations and recommendations are contained throughout the text of the report.

The concept of creating an assessment tool to guide the development and environmental future of the Florida Keys is intriguing; however, the goal established for this study, “to develop a model capable of determining the ability of the Keys ecosystem to withstand all impacts of additional land development activities,” contains ambiguities and imprecision that must be addressed. Some expectations for the Keys Study exceed current scientific understanding and modeling capabilities. Much of the terminology employed in the scope of work is also

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

unclear. For example, the term “carrying capacity” is not easy to define or measure. Nevertheless, the term could be incorporated into the planning tool if its usage and the ways it is to be measured are defined carefully and clearly.

Although many of the goals set and words used were not chosen by the study team members, nevertheless, they should quickly develop a clear and consistent terminology for the study and work to educate all interested parties about the inherent limitations of this ambitious effort. By reviewing some of the published literature on ecological and social system modeling and obtaining more regular input from the expert advisors, the study team can help explain how the final product can best be used by land use planners, other decision makers, and the public in the Florida Keys.

Despite these limitations, the study team’s efforts in data collection and process modeling should still be very useful. Rather than creating a fully predictive numerical simulation model the study team should aim to create an “impact assessment tool” that can be used to help visualize the consequences of various land development scenarios on the Keys’ environmental and social systems. Such a tool could be used in analyzing future development scenarios and could be a powerful aid in helping decision makers understand how the Keys might change under a variety of development scenarios.

The study team should also place an immediate, strong emphasis on specifying the procedures by which the sub-modules will interact. A high level “roadmap” should be constructed, showing every input to and output from each module. In addressing this task it will be best to start at the end, obtaining agreement from key stakeholders about what the final CCAM outputs will be, and how they will be presented. The next step should be to determine the nature of the CCAM scenario inputs. Knowing more about the initial inputs and ultimate outputs will guide much of the module development. Finally, whenever one module produces an output to be used as input to another module, a clear understanding must be reached between the module teams about the space and time scales, level of precision, and units required. Seamless coordination between modules represents one of the greatest challenges to the study team, but not enough resources and time have yet been devoted to this effort.

Although the “big picture” design should be a top priority, the CCAM will only provide meaningful results if each module translates inputs to outputs in a reasonable way, based on an understanding of the parameters and processes involved. To do this to the limits of current knowledge would far exceed the time and money available. Thus, difficult choices will have to be made about which elements to include in each module and at what level of detail. Greater reliance on the expert advisors should be helpful in making these choices.

This committee has been asked by the Keys Study sponsors to provide a second, more detailed review after the draft CCAM is completed in June 2001. For that review to be successful the committee will require relevant CCAM documentation, including a clear summary document, before it begins delibera-

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

tions. In particular, the committee will need to consider such materials as the following:

  1. documents that precisely describe the inputs to and outputs from each module, provide clear explanations of the process for getting from inputs to outputs in each module, and include other relevant information about the inner workings of the CCAM;

  2. documentation of the data used in each module, including their sources, dates, and quality assurance/quality control procedures and results;

  3. explanations of the uncertainties associated with each output from each module and results of sensitivity testing, as discussed in Section 4 of this report;

  4. results of any scenario tests conducted, describing the input parameters, the data transfers between modules, and the module outputs, both numerically and graphically.

Due to the preliminary nature of this interim report, and the rapid turnaround required by the sponsors, the committee’s full evaluation of the final CCAM product may differ in many respects from the statements made here. Nevertheless, the committee hopes that this report will help the CCAM design team achieve a better end-product.

The committee looks forward to continued interactions with the study team and to playing a useful role in evaluating this innovative tool for land use planning and public policy formulation in the Florida Keys.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

References

Dames & Moore, Inc. 2000a. Florida Keys Carrying Capacity Study Project Strategy Outline. Third revision. Tampa, FL: Dames & Moore, Inc.

Dames & Moore, Inc. 2000b. Users Needs Assessment Report. Tampa, FL: Dames & Moore, Inc.

Deyle, Robert E., Steven P. French, Robert B. Olshansky, and Robert G. Paterson. 1998. Hazard Assessment: A Factual Basis for Planning and Mitigation. In Raymond J. Burby (ed.), Cooperating With Nature: Confronting Natural Hazards With Land-Use Planning For Sustainable Communities, pp. 119–166. Washington, D.C.: Joseph Henry Press.


Florida Administration Commission Rule 28.20.100.

Florida Executive Order 96-108.

Florida Department of Community Affairs. 1998. The Local Mitigation Strategy: Cities and Counties Working Together to Build Disaster-Resistant Communities. Tallahassee, FL: The Florida Department of Community Affairs.


Godschalk, David R., Francis H. Parker, and Thomas R. Knoche. 1974. Carrying Capacity: A Basis for Coastal Planning? Chapel Hill, NC: University of North Carolina Department of City and Regional Planning.

Godschalk, David, David Brower, and Timothy Beatley. 1989. Catastrophic Coastal Storms. Durham, NC: Duke University Press.


National Research Council. 1995. Science, Policy, and the Coast: Improving Decisionmaking. Washington, D.C.: National Academy Press.

National Research Council. 2000. Clean Coastal Water, Understanding and Reducing the Effects of Nutrient Pollution. Washington, D.C.: National Academy Press.


Seal et al. 1990. Florida Key Deer Population Viability Assessment. Captive Breeding Specialist Group. Apple Valley, MN.


United States Army Corps of Engineers, Jacksonville District. 1998. Scope of Work for the Florida Keys Carrying Capacity Study.

United States Census. 1998. County Business Patterns.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

Water Environment Federation and American Society of Civil Engineers. 1998. Urban Runoff Quality Management. WEF Manual of Practice No. 23, ASCE Manual and Report on Engineering Practice No. 87. Alexandria, VA: Water Environment Federation.

Watson, Charles C. 1995. The Arbiter of Storms: A High Resolution GIS-Based System for Integrated Storm Hazard Modeling. Natural Weather Digest 20(2): 2–9.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
×

APPENDIX A
Supporting Documents

Dames & Moore, Inc. 2000a. Florida Keys Carrying Capacity Study Project Strategy Outline. Third revision. Tampa, FL: Dames & Moore, Inc.

Dames & Moore, Inc. 2000b. Users Needs Assessment Report. Tampa, FL: Dames & Moore, Inc.

Duck, James C. 2000. Letter to Stephen Parker, National Research Council. August 31.

Florida Administration Commission Rule 28.20.100.

Florida Executive Order 96-108.

United States Army Corps of Engineers, Jacksonville District. 1998. Scope of Work for the Florida Keys Carrying Capacity Study.

United States Army Corps of Engineers, Jacksonville District. 2000. First Series of Public Workshops Minutes. Key Largo Public Library, July 18. http://www.saj.usace.army.mil/projects/pubmeeting.html.

   

Note: Appendix B of the Interim Report is not reprinted here, because the information is the same as Appendix A of the Review of the Florida Keys Carrying Capacity Study Final Report.

Suggested Citation:"Appendix B Interim Review of the Florida Keys Carrying Capacity Study." National Research Council. 2002. A Review of the Florida Keys Carrying Capacity Study. Washington, DC: The National Academies Press. doi: 10.17226/10316.
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Nearly thirty years ago the Florida Keys were designated as an Area of Critical State Concern. The state recognized that Monroe County contained many valuable natural, environmental, historical, and economic resources that required thoughtful management. In 1996, as a result of many years of discussion, negotiation, and litigation, the Florida Administration Commission issued an Executive Order requiring the preparation of a "carrying capacity analysis" for the Florida Keys. To fulfill this requirement, the U.S. Army Corps of Engineers and the Florida Department of Community Affairs jointly sponsored the Florida Keys Carrying Capacity Study (FKCCS). The key component of this study is a carrying capacity analysis model (CCAM) that provides a technical tool for state and local jurisdictions to "determine the ability of the Florida Keys ecosystem, and the various segments thereof, to withstand all impacts of additional land development activities."

This National Research Council (NRC) report provides a critical review of the Florida Keys Carrying Capacity Study: Test Carrying Capacity Analysis Model, First Draft, hereafter referred to as the Draft CCAM. This independent review offers critical commentary in order to assist the sponsors and contractors in making final adjustments to their report and the Carrying Capacity Analysis Model.

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