Benefit-Risk Analysis of Everglades Construction Project Phase I Discharge Alternatives. James D. Englehardt, University of Miami, PO Box 248294, Coral Gables, FL 33124-0630
An ecological, economic benefit-risk analysis of alternatives for discharge of waters to the Everglades during start-up of agricultural drainage water treatment areas is presented in this paper. Currently proposed discharge to northern sawgrass marshes entails risks of cattail expansion, as well as changes in hydroperiod. Alternative "Bypass Plans" to convey water from treatment areas to current discharge points during start-up may result in less cattail expansion, due to the ability of existing cattails to remove phosphorus to the catotelm. The probabilistic, ecological net present values of the Current Plan relative to the Bypass Plan for treatment areas 2, 3/4, 5, and 6 were compared to costs of building bypass canals. Uncertainty in cattail expansion rates was handled by Monte Carlo analysis. Replacement of sawgrass by cattail was considered economically irreversible. Annual values of freshwater marshes were assumed based on previous contingent valuation and basic energy analyses for freshwater marshes in Louisiana and Europe, and compared to market values. Valuation of ecological benefits and losses were based on a conceptual model developed to show ecological interactions. Results favored the Current Plan only in areas where the hydroperiod was improved, and in a potential case where the Bypass plan would involve construction of a new pump station. Sensitivity of results to eutrophic and natural marsh valuations and discount rate were examined.