ABSTRACT
The environmental effects from development and operation are many and of great variety. The consequences are to be seen in the evolution of the practice of impact assessment. For one thing, the scope of the impacts taken into account had been growing. For another, the scope of the planning process, within which they need to be considered, has for some time been extended from discrete projects to programmes, policies and plans, making the role of the assessment more ambitious (O’Riordan & Sewell 1981:1; Breheny 1984:20-24; Rickson et al. 1989; Lee & Walsh 1992). Because of this evolution, the practice of impact assessment has been lumpy and, as in all evolving disciplines, various lumps have originated from differing disciplines. This must accordingly be reflected in our account below of the origins from the various sources.
