Almost all aspects involving alteration of natural environment now require that the impact, interactions and effects of every designed structures towards natural habitat or ecosystems be considered and assessed for any kind of activities. In US, this was in 1970 which the principle was enacted into federal law.
The law requires that environmental impact must be assessed whenever an action or project or activities will cause environmental alteration, impact, as well as requiring that alternatives be identified and considered. Since 1990, a number of programmatic environmental impact statements have been drafted, and many years followed, many countries throughout the world adopted this principle, including of course Indonesia, known as Amdal (Analisa Mengenai Dampak Lingkungan).
Usually, if the project is proposed, there are several stages must be conducted. They are environmental assessment, a finding of no significant impact if that is appropriate, an environmental impact assessment, and a record of decision made following the environmental assessment. Ideal approach of a problem generally consists of a sequence of actions. Those are (1) problem definition, (2) identifying alternative solutions, (3) evaluation of alternatives, (4) action or implementation of a selected solution, and (5) review and revision of the solution implemented. In some extend, there is a decision process after review and review, although this is particulary not so significant.
One thing to remember is to assess environmental impact, we need analytical tools as well as the specific impacts and mitigation measures, which are discussed later. The keypoint here is impact assessment provides an integrated view of the problems of environmental engineering.