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What is it?

An Environmental Impact Assessment (EIA) is an analytical process that systematically examines the possible environmental consequences of a project´s implementation. EIA provides a way of assessing key issues effectively and transparently, and highlights opportunities to achieve wider environmental objectives. An EIA is carried out for new projects that are likely to have significant adverse impacts on the environment.
An Environmental Management Plan (EMP) is one of the outputs of an EIA process. An EMP establishes how impact mitigation measures are to be implemented and monitored.

What can it be used for?

An EIA provides competent environmental authorities insight on the environmental risks of a project to determine if it should be rejected, approved, or approved conditioned to the implementation of mitigation measures. It is also used by the EU to determine the acceptability of a project on environmental grounds, and elements to improve its design from an environmental sustainability perspective.
The EMP is used to ensure the impact mitigation measures get implemented and provides the elements to monitor key environmental variables.

When can it be used?

The need for an EIA is determined by the environment and climate risk screening process.
The EIA and EMP are prepared during formulation and the EMP is implemented and monitored with the project.

Who can use it?
  • The EIA is used by the EU and competent authorities involved in determining the feasibility of a project on environmental grounds. It is also useful for the project proponent to enhance the project's design.
  • The EMP is used by the project proponent and the EU to monitor the effectiveness of the mitigation measures. The EU needs to ensure that the EMP is reflected in the relevant contractual documents.
What are its strengths?
  • It allows to identify projects that have unacceptable potential impacts on the environment and should thus not be further pursued, and provides recommendations to improve the environmental performance of other projects subject to an EIA.
What are its limitations?
  • Depending on the scope of the project, EIAs can take time to complete, which must be factored into the project formulation process.
  • National EIA systems are sometimes weak, so the EU must ensure adherence to the standards set by the EU EIA Directive.


Key elements

The need for an EIA is determined by a screening process (Annex 3 of the Guidelines). An EIA consists of the following typical components: (A) screening; (B) scoping; (C) identification of potential impacts; (D) impact assessment; (E) analysis of alternatives; (F) EIA report; (G) preparation of an Environmental Management Plan (EMP). Public participation should be integrated throughout the process.


Data/information. Preparation of and EIA requires extensive details of the project, considering its construction, operation and decommissioning phases. It also requires data for a variety of dimensions: biological, physical, sociological, cultural of the receiving environment. Various impact identification and assessment methodologies are available, which vary depending on the type of project (e.g. Leopold-type matrices, cause-effect diagrams, map overlays, mathematical modelling, habitat fragmentation analysis). Quantitative assessments are the norm in EIA, but qualitative approaches may be required when data availability or quality if lacking.

Time. The time required to prepare an EIA can vary a lot, depending on the complexity of the project. EIAs require more time than other types of assessment (e.g. SEA), given the level of detail required, and the need to prepare an environmental baseline (which can require the generation of primary data). The time require can be calculated in months, although more than a year may be necessary for highly complex projects for which incomplete baseline information is available.

Skills. An EIA requires an interdisciplinary team able to assess the potential impacts of all project components on the different environmental and social components, particularly where scoping indicates the existence of complex issues.

Facilities and materials. N/A

Financial costs and sources. Cost of an EIA has been estimated to be generally less than 1% of the total project cost.

Tips and tricks

The scoping phase is critical to define, at an early stage, the key issues the EIA will focus on. Public participation is fundamental to identify key risks and concerns.

The EU EIA Directive requires that an EIA also assessed the project's vulnerability to climate change. In this sense, the elements of a Climate Risk Assessment (CRA) can be incorporated into the EIA.


Where to find it

The European Commission, Tools and Methods Series, 2016. Guidelines N. 6, Integrating the environment and climate change into EU international cooperation and development (Annex 6, Terms of reference for an Environmental Impact Assessment)

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