The Decision-Identification Tree: A New NEPA Scoping Tool

/ No single methodology has been universally accepted for determining the appropriate scope of analysis for an environmental impact statement (EIS). Most typically, the scope of analysis is determined by first identifying actions and facilities that need to be analyzed. Once the scope of actions and facilities is identified, the scope of impacts is determined. Yet agencies sometimes complete an EIS only to discover that the analysis does not adequately support decisions that need to be made. Such discrepancies can often be traced to disconnects between scoping, the subsequent analysis, and the final decision-making process that follows. A new and markedly different approach-decision-based scoping-provides an effective methodology for improving the EIS scoping process. Decision-based scoping, in conjunction with a new tool, the decision-identification tree (DIT), places emphasis on first identifying the potential decisions that may eventually need to be made. The DIT provides a methodology for mapping alternative courses of action as a function of fundamental decision points. Once these decision points have been correctly identified, the range of actions, alternatives, and impacts can be more accurately assessed; this approach can improve the effectiveness of EIS planning, while reducing the risk of future disconnects between the EIS analysis and reaching a final decision. This approach also has applications in other planning disciplines beyond that of the EIS.