In principle, an environmental impact assessment (EIA) system could apply to all actions likely to have significant environmental impact, irrespective of their type. Thus, the potential scope of a comprehensive EIA system could encompass the approval of policies, plans, programmes and projects at all levels of government. Lee & Wood (1978) have suggested a ‘tiered’ system of EIA applied to a chronological sequence of category of action, as shown in Figure 6.1.
There are several advantages associated with an EIA system that is not confined to projects. In particular, higher levels of action not subject to environmental assessment may generate projects which are misspecified or which lack sufficient alternatives. Similarly, there may be time savings if environmental data are collected when a higher-order action is proposed rather than after an urgent project is suggested or if the assessment of a plan or
Figure 6.1 Categories of action and levels of government within a comprehensive EIA system.