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Environmental impact assessment (EIA) was developed as a tool to minimize negative impact of human activities on the environment.

EIA is one of the environmental assessment tools being used worldwide to provide decision-makers and the concerned public with essential information to plan for environmentally sustainable economic development. It is a systematic analysis of projects to determine their potential environmental impacts and the significance of such impacts and to propose measures to mitigate the negative impacts.

Decisions on whether development goes ahead or not may involve trade-offs between an environment, which is considered to be desirable and healthy, 'quality of life' issues, and economic gain. Whilst it may not resolve such issues, EIA aims to make explicit to society what the consequences of such trade-offs might be and so ensure decision-makers are more accountable for their decisions.

Environmental problems in the developing world are often linked to unbalanced or inappropriate development.


The purpose of the environmental impact assessment is to

  • Assess the impact of a proposed activity on the environment before making the decision on whether to carry it out, and
  • Develop and assess measures to avoid or minimize those impacts if it is decided to carry out the activity.

Key issues in EIA

In order to identify the likely consequences of development, a series of steps must be undertaken to ensure that issues are approached in a systematic and rational way. These stages form what is known as the EIA process. The process is iterative, which means that it is not linear, but stages in the process recur and feed back into the process and the design of the project as new information is gathered. There are a number of key issues which run through EIA in all countries and which are essential components of the process, and which are highlighted below.

When is EIA required?

EIA is required for all projects that have been identified as likely to have a significant effect upon the environment. As you can probably imagine, defining what is 'significant' is not a simple task. The approaches used in different countries are outlined later.

When does EIA start?

To be effective, EIA should start early in the planning of a project in order materially to influence the design and location. There are a number of advantages and disadvantages of undertaking EIA at an early stage. Advantages include fewer costs associated with rethinking a project, or delays resulting from an attempt to mitigate impacts late in the design process. The project is more likely to be accepted if it has dealt with the concerns of the local people at an early stage; EIA can be seen as aiding good environmental public relations. Cost-effective design, taking the environment into account, often means that the overall project development costs are reduced

Disadvantages of undertaking EIA early in the development process include the difficulty of assessing the impacts of a project which is not fully designed. It may be difficult to predict the costs of EIA, and indeed the project, when the final outcome is unknown as a result of not knowing what effects the consideration of the environment may have on the project.

What should be covered in an EIA?

It is important that the number of impacts considered in an EIA is reduced to a manageable number of key issues at an early stage. This helps to direct resources towards addressing important issues, which are of concern to involved parties and the wider public. Examples of the types of issues, which may be included, are pollution of watercourses, visual intrusion in a sensitive landscape, or the destruction of a habitat or area important for its cultural heritage.

Who carries out EIAs?

This varies in different counties. Frequently, it is the developer or environmental consultants acting on behalf of the developer who carry out EIAs. However, in other cases, the EIA can be commissioned by the decision-making authority or undertaken by an independent body.

What about the public?

Consultation and participation have formed an integral part of the EIA process since its inception and most EIA systems make some provision for the involvement of the public. The public have a democratic right to be informed about projects that will affect the environment in which they live and to voice their concerns. There is growing acceptance that increased consultation and participation can produce significant benefits for both the project proponent and those affected.

How are the results of the EIA presented?

The environmental impact statement (EIS) is the document that is presented to the decision-making body, alongside the application for development consent. It contains the environmental information and conclusions of the assessment and should be presented in a clear, unbiased manner, enabling non-specialists to determine what issues are at stake. A non-technical summary is often produced for wider distribution. Public meetings, exhibitions, and displays also provide a means of disseminating information to the public

Approach / Methodology

EIA is both a planning tool and a decision-making tool.

As a planning tool, EIA presents methodologies and techniques for identifying, predicting, and evaluating potential environmental impacts of projects as per the project cycle.

As a decision-making tool, it provides information that promotes policy-making and actions that ensure sustainability in the implemented projects.

Best-practice EIA identifies environmental risks, lessens conflicts by promoting community participation, minimizes adverse environmental effects, informs decision-makers, and helps lay the base for environmentally sound projects.

Benefits of integrating EIA have been observed in all stages of a project, from exploration and planning through construction, operations, decommissioning, and beyond site closure.

Overview of the stages of the EIA process

The following briefly presents an overview of the stages of EIA to help place them in the context of the whole process.


The EIA process begins from the very start of a project. Once a developer has identified a need and assessed all the possible alternatives of project design and sites to select a preferred alternative, two important questions must be asked: 'What will be the effects of this development on the environment? Are those effects significant?' If the answer to the second question is 'yes', an EIA may be required. Answering this question is a process known as screening and can be an essential first step into a formal EIA.

The EIA process is, it must be stressed, iterative. This is demonstrated at this early stage of screening where the requirement for a formal EIA and its associated cost implications can lead the developer to reassess the project design with a view to reducing the significant impacts to a level where an EIA is not legally required (Nielsen et al 2005).


Where it is decided that a formal EIA is required, the next stage is to define the issues that need to be addressed, that is, those impacts that have a significant effect on the environment. This is known as scoping and is essential for focusing the available resources on the relevant issues.

Baseline study

Following on from scoping, it is essential to collect all relevant information on the current status of the environment. This study is referred to as a baseline study as it provides a baseline against which change due to a development can be measured.

Impact prediction

Once the baseline study information is available, the important task of impact prediction can begin. Impact prediction involves forecasting the likely changes in the environment that will occur as a result of the development.

Impact assessment

The next phase involves the assessment of the identified impacts - impact assessment. This requires interpretation of the importance or significance of the impacts to provide a conclusion, which can ultimately be used by decision-makers in determining the fate of the project application.


Frequently, the assessment of impacts will reveal damaging effects upon the environment. These may be alleviated by mitigation measures. Mitigation involves taking measures to reduce or remove environmental impacts and it can be seen that the iterative nature of the EIA process is well demonstrated here.

Producing the environmental impact statement

The outcome of an EIA is usually a formal document, known as an environmental impact statement (EIS), which sets out factual information relating to the development, and all the information gathered relating to screening, scoping, baseline study, impact prediction and assessment, mitigation, and monitoring measures. It is quite common that a requirement of an EIS is that it also produces a non-technical summary. This is a summary of the information contained within the EIS, presented in a concise non-technical format, for those who do not wish to read the detailed documents.

EIS review

Once the EIA is complete, the EIS is submitted to the competent authority. This is the body with the authority to permit or refuse development applications. Basically, the review process should enable the decision-maker to decide whether the EIS is adequate (eg whether it is legally compliant), whether the information is correct, and whether it is unbiased. If it is, they are then in a position to use the EIS as information to be considered in determining whether the project should receive consent.

The competent authority is now in possession of the information they require about the possible effects of the development on the environment.

Follow up

Follow up relates to the post-approval phase of EIA and encompasses monitoring of impacts, the continued environmental management of a project, and impact auditing. Follow up presents an opportunity both to control environmental effects and to learn from the process and cause-effect relationships. Ideally, data generated by monitoring and other aspects of follow up should be compared with the original predictions and mitigation measures in the EIS to determine

  • the accuracy of the original predictions
  • the degree of the deviation from the predictions
  • the possible reasons for any deviation
  • whether mitigation measures have achieved their objective of reducing or eliminating impacts

Information generated by this process can contribute to the improvement of future EIA practice, for example, by enabling more accurate predictions to be made.

General Process in EIA

Figure: Key Stages of EIA

Key Stages of EIA


Main Participants of EIA Study

EIA applies to public and private sections. The six main players are:

  • Those who propose the project
  • The environmental consultant who prepare EIA on behalf of project proponent.
  • Pollution Control Board (State or National).
  • Public has the right to express their opinion.
  • The Impact Assessment Agency.
  • Regional centre of the Ministry of Environment and Forest.

After 2006 Amendment the EIA cycle comprises of four stages

  1. Screening
  2. Scoping
  3. Public hearing
  4. Appraisal

Category A projects require mandatory environmental clearance and thus they do not undergo the screening process.

environment impact assessment

Category B projects undergoes screening process and they are classified into two types.

  • Category B, projects (Mandatorily requires EIA).
  • Category B2 projects (Do not require EIA).

Thus, Category A projects and Category B, projects undergo the complete EIA process whereas Category B2 projects are excluded from complete EIA process.

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