10
Conclusions

URS Corp. has been generally responsive to the concerns raised in the NRC Committee’s interim report (National Research Council, 2001), and the CCAM has been brought to a state of development beyond that anticipated at the time the interim report was submitted. The Committee greatly appreciates the contractor’s responses to its many questions, both written and oral, during the preparation of this final review. The ambitious vision that stimulated the development of the CCAM and the effort made by the contractor to fulfill that vision remain impressive.

At its present state of development, the six CCAM modules and the Scenario Generator have reached very different levels of development and consist of assumptions, formulations, and coefficients of widely varying credibility. As noted in Section 2 of this report, virtually all of the components suffer from several common fundamental problems and, as detailed in Sections 3–9 of this report, each module has a unique set of strengths and weaknesses. Given the many concerns described in this report, the Committee does not believe that the current version of the CCAM is ready to be used “as an impact assessment tool to support regional land use policy decisions” or to provide “an effective framework to determine whether scenarios fall within the carrying capacity of the Florida Keys, determined by a set of ecological, socioeconomic, and human infrastructure thresholds and criteria.” (URS Corporation, Inc., 2001a).

On a more positive note, several of the modules can be used in their current state, or with a modest level of additional effort, as tools to help assess a limited set of environmental, socioeconomic, fiscal, and infrastructure impacts of land use change in the Florida Keys. Even in those cases, however, it should be



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A Review of the Florida Keys Carrying Capacity Study 10 Conclusions URS Corp. has been generally responsive to the concerns raised in the NRC Committee’s interim report (National Research Council, 2001), and the CCAM has been brought to a state of development beyond that anticipated at the time the interim report was submitted. The Committee greatly appreciates the contractor’s responses to its many questions, both written and oral, during the preparation of this final review. The ambitious vision that stimulated the development of the CCAM and the effort made by the contractor to fulfill that vision remain impressive. At its present state of development, the six CCAM modules and the Scenario Generator have reached very different levels of development and consist of assumptions, formulations, and coefficients of widely varying credibility. As noted in Section 2 of this report, virtually all of the components suffer from several common fundamental problems and, as detailed in Sections 3–9 of this report, each module has a unique set of strengths and weaknesses. Given the many concerns described in this report, the Committee does not believe that the current version of the CCAM is ready to be used “as an impact assessment tool to support regional land use policy decisions” or to provide “an effective framework to determine whether scenarios fall within the carrying capacity of the Florida Keys, determined by a set of ecological, socioeconomic, and human infrastructure thresholds and criteria.” (URS Corporation, Inc., 2001a). On a more positive note, several of the modules can be used in their current state, or with a modest level of additional effort, as tools to help assess a limited set of environmental, socioeconomic, fiscal, and infrastructure impacts of land use change in the Florida Keys. Even in those cases, however, it should be

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A Review of the Florida Keys Carrying Capacity Study emphasized that the outcomes calculated by the Draft CCAM modules must be considered carefully and evaluated in the context of observational data, experience, and professional judgement. The reliability and utility of the individual modules have been assessed as follows: Scenario Generator—While the lack of a good description of current conditions in the Florida Keys hinders the development and evaluation of scenarios, the NRC Committee has no major technical criticisms of the Scenario Generator of the CCAM. It appears to be appropriate and flexible. The GUI should be modified to allow users to set coefficients and thresholds for individual modules, and the model threshold output should be modified to generate continuous color-density gradients rather than three-color thresholds. Socioeconomic and Quality of Life Modules—As currently constructed, these modules are seriously compromised and should not be used without the extensive modifications described in Section 4 of this review. Using current data to calculate the Affordable Housing Index (AHI) means that it cannot be used as an impact assessment variable to analyze different scenarios. In order to be useful, the AHI must change as scenario conditions change. Furthermore, the Competitive Commerce Index (CCI) has no clear meaning or significance. These two measures—the only socioeconomic/quality of life indicators calculated—fail to provide a comprehensive or accurate representation of the quality of life or socioeconomic well-being of people in the Florida Keys. The Committee was surprised to see that tourism has not been adequately considered in the model, thus ensuring that a large part of the Florida Keys economy is poorly represented at best. Fiscal Module—This module is straightforward and credible. A few modifications and additions have been suggested, but this component of the CCAM seems ready for use with little additional effort. Human Infrastructure Module—This module has two interrelated yet uncoupled components: level of service on U.S. Route 1 and hurricane evacuation clearance time. The first component is currently useful and needs only minor improvements in documentation. The hurricane evacuation component, however, has serious flaws. The model makes the unrealistic assumption of a linear relationship between total population within the Florida Keys and evacuation times. As a result, it fails to account for spatial differences in growth and the interaction of these differences with bottlenecks along U.S. Route 1. This component of the CCAM should not be used unless the time and resources are available to incorporate the existing evacuation clearance model prepared by Miller Consulting into the CCAM. If that model is added, all of its methods, assumptions, and uncertainties should be fully documented in the CCAM report.

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A Review of the Florida Keys Carrying Capacity Study Integrated Water Module—This module has three components, one dealing with stormwater runoff, one with wastewater, and the last with potable water supply and sewage. Taken as a whole, the Integrated Water Module is one of the most substantial parts of the CCAM. It will be useful as a first order tool after only minor revisions and additions, and may prove helpful to address certain questions dealing with water issues. The lack of calibration and the time averaging of runoff make the module unsuitable for drawing inferences about the impact of runoff or sewage on receiving water quality, an important limitation. Marine Module—It is most unfortunate that a component of the Florida Keys environment that generates much public concern and constitutes the major tourist attraction of Monroe County is represented by the weakest component of the CCAM. The contractor appears to have made a serious effort to create a useful Marine Module, but was unable to develop convincing quantitative relationships between land use, population, and environmental conditions in near-shore waters. Such relationships could be developed in some cases, but it seems extremely unlikely that they will be discovered and included as part of the current effort. Moreover, the Integrated Water Module’s treatment of nutrients and metals delivered to the coast is so crude that in this regard, the Committee believes the model is more misleading than it is helpful. The Committee recommends that this module not be used at all unless it undergoes drastic revision. The near-shore environment of the Florida Keys will have to be the subject of a more focused effort with more support and time at some point in the future. Terrestrial Module—In contrast to the Marine Module’s handling of the marine environment, issues of terrestrial habitat and species richness appear to be reasonably well addressed by the Terrestrial Module. Section 9 of this report identified several important technical concerns that will require only a modest effort to make this component useful for relating land use changes to wildlife habitat in the Florida Keys. SUMMARY In summary, the Marine Module should not be used in its current form, nor should the Socioeconomic Module and hurricane evacuation component of the Human Infrastructure Module without thorough revision. The remaining modules need relatively modest technical adjustments and corrections before they can play a helpful, if limited, role in estimating some of the impacts of various land use scenarios in the Florida Keys. This assessment will disappoint many of those who had hoped for a powerful new tool that would provide credible predictions of the environmental and social consequences of human decisions and actions. These conclusions must also come as a disappointment to those who took on what was, in truth, an impossible

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A Review of the Florida Keys Carrying Capacity Study task and gave it their best effort. It is important to measure their success against the difficulty of the charge they were given and the time available for the work. In many ways this was a pioneering effort and its major long-term benefit may lie in the heuristic value of the exercise and in the personal interactions and exchanges among members of the public, environmental scientists, and planners who took part in the process of model development. The current knowledge base in the environmental and social sciences is simply not yet adequate to enable anyone to “determine the ability of the Florida Keys ecosystem to withstand all impacts of additional land development activities.” That knowledge cannot be ordered up no matter how badly it is needed or desired. It will only come from patient work and support, rare moments of creative insight, and a continuing investment in synthetic efforts such as the one reviewed here. In this effort there is no failure, only slower or faster rates of learning and progress.