INTRODUCTION

Scientists, engineers, and economists working as environmental consultants are in a unique position to address the practical aspects of a working definition of “adverse environmental impact” (AEI). In our contacts with the electric utility industry, various regulatory agencies, and the legal community, we have encountered numerous and sometimes conflicting interpretations of what constitutes AEI. Over the last 30 or more years, Lawler, Matusky & Skelly Engineers LLP (LMS) has applied most of the suggested approaches with varying degrees of acceptance. In this paper, we share some of our experiences with the hope of providing insight into the development of a useful methodology for meeting the statutory requirements of §316(b) of the Clean Water Act. To establish a common understanding, we must first ask, “Why do we care about a definition of AEI?” The answer to this requires that we examine the wording of the 316(b) regulation itself.