The decision to build a nuclear power plant at Calvert Cliffs on the western shore of the Chesapeake Bay in southern Maryland resulted in a Iandmark legal decision (Calvert Cliffs Coordinating Committee vs Atomic Energy Commission) and began one ofthe mostintensive long-term studies ever carried out in an American estuarine system. In the pages that follow we describe the major results and findings from studies conducted over more than a decade by scientists from The Academy of Natural Seiences of Philadelphia (ANSP). These studies were designed to assess the potential effects that operation...