The study is concerned with the design of administrative arrangements for managing water quality on a regional system basis. It reviews existing water quality decision-making arrangements and presents two case studies on water quality management decisions in Wisconsin to indicate how groups and political parties have functioned in dealing with water quality management. The implications of the regional system approach for the design of administrative arrangements are then examined and design criteria for such arrangements developed on the basis of the current literature on organizational theory. These criteria are then applied in an evaluation of three alternative administrative models. One of these is a simple extension of existing arrangements with the existing Department of Natural Resources operating the regional system. In the second, a regional water quality management agency is envisaged as operating the regional system with the Department of Natural Resources establishing and enforcing standards. (WRSIC abstract)