Environmental Impact Assessment


Environmental impact assessment (EIA) is a systematic process designed to identify and predict the potential impacts of human activity on the biophysical and human environment. It also functions as an environmental management tool to identify measures to avoid, mitigate or compensate for those effects. EIA is intended to be an iterative process to follow‐up to projects postimplementation to determine actual environmental outcomes, interpret and communicate information about those outcomes and investigate opportunities for improved project environmental performance. Originating from the United States’ National Environmental Policy Act of 1970, EIA is now amongst the most successful and widely practiced environmental management tools in the world.

Key Concepts:

  • EIA is an aid to decision making through which concerns about the potential environmental consequences of proposed projects are assessed before those projects become a reality.

  • Screening in EIA ensures that assessments are done when needed and not done when not needed.

  • Scope is essential to good EIA and the goal is to focus on a select set of environmental components that are deemed important from scientific, public or regulatory perspectives and are likely to be adversely affected by the project.

  • The underlying intent of EIA is to allow project proponents, managers and decision makers to enhance the benefits of proposed development projects and to mitigate potentially adverse impacts to the point of acceptability.

  • EIA must be applied early in the development planning processes if it is to be influential in project design and decision making.

  • Information gained in EIA follow‐up studies, after the project is implemented, provides feedback to improve predictions and mitigation and management programmes, and an opportunity to learn for subsequent project proposals.

Keywords: environmental impact assessment; baseline studies; impact prediction; mitigation and management of impacts; cumulative environmental effects; follow‐up studies

Figure 1.

Generic environmental impact assessment process.



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Further Reading

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United States Council on Environmental Quality. http://www.whitehouse.gov/administration/eop/ceq/. About the Council on Environmental Quality.

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Noble, Bram F(Sep 2011) Environmental Impact Assessment. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0003253.pub2]