Environmental Impact Assessment

An Environmental Impact Assessment (EIA) is an ex ante analytical process for identifying and assessing the potential environmental impacts of a project in its different phases (construction, operation and decommissioning). EIA applies to projects with potential significant adverse impacts on the environment, and informs the development consent process. An EIA proposes measures to avoid and/or mitigate negative impacts, optimise positive effects, and includes an Environmental Management Plan (EMP) laying out how such measures should be implemented and monitored.

Based on the EIA the project can be approved without changes or conditions; approved with minor changes; subjected to major changes that justify new studies; or judged unacceptable, even with corrective measures, and therefore refused. EIAs are normally prepared under the requirements of national EIA systems, but can also be required by the EU based on its own standards.

Public participation and transparency are fundamental principles of an EIA. Meaningful opportunities must be given for all stakeholders and the public in general, to engage throughout the EIA process, in consistency with the obligations under the Aarhus Convention.

For further guidance on this subject, refer to the Model Terms of Reference for an Environmental Impact Assessment.

The main stages of an EIA are:

1. EIA Screening

Screening refers to the decision to carry out the EIA, based on national legislation, the nature of the project and the sensitivity of the environment.

2. EIA Scoping

The Scoping helps to define the aspects that need to be covered in the EIA study, such as the key environmental issues to consider; the time-frame; the geographical area; the legislative and institutional framework; key stakeholders views and concerns; and specific assessment methodologies to be employed.

3. EIA study

A baseline study describes the initial state of the environment within the selected boundaries of the study area. It also includes the description of the “no project” scenario, based on assumptions regarding future changes. Another important step is the identification and evaluation of the potential significant environmental impacts. The impacts are the differences between the situation with, and the situation without the project. The identification and assessments of impacts are necessary for all alternatives under study, in order to compare them and provide recommendations on the selection of the most environmentally sound alternative. It may be decided to undertake a more detailed assessment of a preferred alternative. The last part of the study provides recommendations, mitigation/optimization measures and the Environmental Management Plan (EMP). Measures should be proposed to avoid/mitigate negative impacts (mitigation measures), as well as to optimize positive effects.

Guidance and reports on EIA

Model Terms of Reference for an Environmental Impact Assessment

Text of EIA Directive 2014/52/EU

Review process of the European Commission EIA directive

Revised Directive on impact assessment of projects enters into application for Member States (16/05/2017)

Commission guidance document on streamlining environmental assessments conducted under Article 2(3) of the EIA Directive (26/07/2016)

Group of EIA/SEA National Experts

International Association for Impact Assessment publications

Directory of Impact Assessment Guidelines, IIED, 1998

EIA in Developing Countries: An Overview (2003)

Environment Guide, a guide to environmental screening, DFID, 2003

Environmental Impact Assessment for Developing Countries in Asia, ADB, 1997