A retrospective evaluation of 316(b) mitigation options using a decision analysis framework

Abstract

Choosing the best 316(b) mitigation option is a daunting task. Decision analysis (DA) provides an objective framework that can be used to choose among several mitigation strategies where there are multiple objectives and numerous uncertainties. This paper has two objectives: (1) to illustrate the use of the DA framework for making a 316(b) decision (using the Chalk Point Power Station as a case study); and (2) to show that DA is also useful for quantifying the benefits of a previous decision. The Chalk Point case, resolved in 1990, centered around the mitigation of adverse environmental impacts of a cooling water intake structure (CWIS) as a result of fish and blue crab losses associated with impingement and entrainment. Barrier nets and fishery enhancement programs were used to mitigate the losses. We compare the costs and benefits of the mitigation options actually employed to those of other options. The costs and benefits were estimated numerically using standard DA methods. Valuations and probabilities were derived largely by professional judgment based upon the original Chalk Point 316(b) studies and ongoing monitoring. DA indicated that the optimal strategy and expected utility were functions of the weighting of environmental benefits relative to cost.