Environmental Impact Analysis of Aquatic Ecosystems Using Rational Threshold Value Methodologies

Abstract

The techniques generally applicable to environmental impact analysis fall short of effective predictive capacity because of incomplete data bases and the lack of procedures for systematic data analysis to maximize data utility. To overcome these difficulties, the Construction Engineering Research Laboratory of the Department of the Army has developed a computer-based environmental impact analysis system. As part of this continuing activity, the Environmental Impact Computer System (EICS) has been used as a basis for development of a detailed subprogram for predicting impacts on aquatic ecosystems. The EICS system is based on the development of methodology for determination of rational threshold values (RTV). RTV includes indexes of both structural and functional community conditions that are integrated into a decision algorithm. Data for community parameters are obtained from readily available resources [STORET, National Pollution Discharge Elimination System (NPDES) permit reporting, and other state and federal water-quality monitoring efforts], system subprograms that provide population predictions based on state-of-the-art population models, and actual field data. The protocols described include interactive, real-time manipulation of data based on site-specific information. The application of these protocols provides a new dimension in impact analysis methodology. Ecosystem-specific threshold levels can be set, and impacts caused by alternatives can be evaluated efficiently and economically. This paper summarizes aquatic ecosystem RTV analysis procedures, discusses feasibility of application, and provides a sound quantitative approach to priority ordering of community parameters for aquatic ecosystem impact analysis.