Interim Review of the Florida Keys Carrying Capacity Study (2001)

In addition to defining the inputs, outputs, and linkages betweenthe individual modules (as discussed in the previous section) projectmanagers should also immediately address: (1) the nature of the externalinputs to the CCAM, from data sources or as specified in future scenarios;(2) the mechanisms and thresholds used in each module; and (3) thefinal outputs generated for the users. External data sources arediscussed in greater detail in Section 6, and inputs from futurescenarios in Section 5. The nature and acceptable format of all theseinputs should be specified from the start and included in the coordinationprocess called for in Section 2. The inner workings of each moduleare also discussed in Section 4. This section focuses on the finaloutputs from the assessment tool and on the determination of practical“thresholds.” As discussed in Section 1, clear, objective biological and socialthresholds of viability rarely exist. Stakeholders, users, and technicalexperts should be consulted to help define thresholds and outputsthat meet the project's dual objectives for comprehensive planningand environmental impact assessment.

It is clear that the CCAM development team recognizes the importanceof creating an assessment tool that addresses the diverse concernsof many stakeholders. The team has expended substantial energy consultingwith the intended CCAM users, including Monroe county, its municipalities,and the concerned public, through extensive interviews and publicmeetings. Although these efforts helped generate a list of topicsof concern (included in the contractor's User Needs Assessment Report,Dames and Moore, 2000b), participants in the January workshop werenot shown a comprehensive, prioritized list of environmental andsocio-economic variables for which assessments will be conductedand final outputs provided. The design of the entire CCAM shouldbe driven by the environmental and socio-economic impacts of greatest concernto stakeholders, users, and technical experts, recognizing the needto prioritize in light of time and money constraints.

A limited set of appropriate outputs should be selected as neededfor the likely applications of the assessment tool, including periodicreviews of comprehensive plans, proposed changes in land developmentregulations, assessments of specific large-scale changes in landuse, permitting, enforcement, and adaptive management (see Section5). Evaluation criteria should then be defined for the variablesof greatest concern. Due to resource constraints, not every usefulor desirable output can be included. Difficult choices must be madeby the design team, with input from expert advisors and stakeholders.(The emphasis on using a geographic information system base throughoutthe CCAM will facilitate the output process and is one excellentfeature of the current plan.) It is urgent that output specificationsbe defined promptly to ensure that each module and the overall projectis properly designed to meet user needs. The results of this exerciseshould also be fed directly into the module coordination processdiscussed in Section 2 to ensure that each module design team knowswhat it is responsible for producing.

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

Although it is not feasible to accurately define ecological thresholdsfor all species and ecosystems in the Keys (due to limitations indata and understanding or the inherent complexity of nature), itis 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 assessmenttool will consist of an array of environmental and socio-economicparameters, the values of which are presented on simplified ordinalimpact scales, such as high, medium, and low or red, yellow, andgreen. The module designers would assign these values based on theirbest professional judgment. This vision will not provide state agenciesor local planners with clear answers about when critical thresholdshave been exceeded, as required by Administration Commission Rule28.20.100 and Executive Order 96-108. This approach will also producean insensitive assessment tool, offering users little informationabout the relative impacts of alternative land development scenarios.

This committee suggests consideration of an alternative approachto designing the CCAM, in which users and experts agree on thresholdsfor specific evaluation criteria (similar to the process suggestedin NRC, 1995). These consensus thresholds can then be used to excludeland development scenarios from further consideration if they posesignificant threats to environmental or community integrity. At leastthree kinds of critical thresholds might exist:

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

2. thresholds for environmental parameters which if exceeded would posea significant threat to the long-term survival of individual speciesor biological communities in the Keys ecosystems, based on the bestprofessional judgment of technical experts;

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

These thresholds could then be used, not to define the maximum humanpopulation that can be sustained but to assess how specific changesin land development affect the survival of species or biologicalcommunities, compliance with regulatory standards, and quality oflife measures. Any development scenario (whether based on changesto comprehensive plans, land development regulations, or specificpermits) whose impacts would exceed one of the thresholds would bejudged as likely to exceed the human and/or biological carrying capacityof the Keys. An alternative that does not exceed any of the exclusionary criteria can be further evaluated to minimizeharmful impacts and maximize positive impacts based on a broaderrange of user-defined evaluation criteria included in the assessmenttool.

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