What Is An Environmental Impact Assessment? A Quick Guide To EIA’s

Are you about to embark on a project (big, small or in between) and just realised that you have to do something called an Environmental Impact Assessment (EIA)? Does the term sound vaguely familiar but you would like more info on the ins and outs of the process? Or perhaps you just wondered how developments like highways or those wind turbines you see on your way to work have factored in the environment?

Then you should read this article to get the lowdown on what exactly an EIA is. Find out:

  • who needs to do one;
  • what types of environmental factors need to be considered;
  • who is involved in the process;
  • how to put together an environmental impact assessment report.

What Is An Environmental Impact Assessment?

An environmental impact assessment is a method used to determine the environmental and social consequences of a project or policy. So whether that’s government plans to build a new highway or a property developer wanting to build houses, an environmental impact assessment is used to see what kind of consequences these developments would have on the local environment.

Most countries around the world have legislation in place that requires the use of EIAs.

Key features of an environmental impact assessment:

  • Environmental implications are considered before the project is approved.
  • The findings are published in a report that has to be made public.
  • The public is consulted about the environmental impacts of the development.
  • Decision making is more inclusive (in theory)


Given the global awareness of the environmental problems we face as a society, most governments recognize the need to prevent further environmental harm from happening. Doing an environmental impact assessment before a project is implemented can identify potential environmental and social issues such as habitat destruction and noise pollution.

environmental impact assessment

An environmental impact assessment is a structured process where the environmental consequences of a project can be defined and assessed. Not only is an environmental impact assessment a way to understand the environmental effects of a project but it must provide solutions to mitigate any harm that may be caused.

What Types of Environmental Factors Are Considered?

Specific environmental factors may vary between countries but under EU law these are the areas that must be addressed in an environmental impact assessment.

The report should cover:

  • Impacts related to climate change (mitigation and adaptation)
  • Impacts related to biodiversity
  • Risks of major accidents and disasters
  • Use of natural resources

Climate change

Two main issues should be addressed in the report, firstly the project’s potential greenhouse gas emissions and whether it will contribute to climate change. Secondly, the vulnerability of the project to the future impacts of climate change (heatwaves, drought, extreme rainfall etc.)


Will the project have negative consequences for species and different ecosystem types in the surrounding area? Factors that should be addressed include; loss of species diversity, loss of genetic diversity, degradation of habitats, and loss of ecosystem services (the benefits we get from nature such as air purification).

The report should also pay special attention to vulnerable species and habitats as identified by the EU Habitats Directive and the Birds Directive respectively.

Risk of major accidents and disasters

The risk of causing accidents and disasters and the associated impact on human health and the environment must be assessed.

As does the project’s vulnerability to both natural and man-made disasters. Both of these factors must be identified in the report and plans must be implemented to manage the risks.

Use of natural resources

How sustainable is the project? Are there any resource depletion risks? Factors of concern here are the types of materials and natural resources used (water, land, biodiversity) and the sustainability of these resources in the longer term. Also, energy demand and use in the operational phase of the project should be assessed.

How Does An Environmental Impact Assessment Work?

There are several stages to completing an environmental impact assessment before the project gets permission to go ahead.

The steps of an environmental impact assessment:

  1. Screening- the first stage is to decide whether the project requires an environmental impact assessment (usually decided by the relevant authority, typically the national government). This decision must then be made public so interested parties can be part of the process.
  2. Scoping – the scope of the assessment is then defined either by the relevant authorities or the developers i.e what type of information needs to be included in the report and what impacts must be assessed.
  3. The EIA report- the report is usually prepared by experts employed by the developer. The report must lay out in clear terms the environmental effects of the project, examination of alternatives and potential methods to mitigate harmful environmental impacts. Also (under EU law) a non-technical summary must be included.
  4. Consultation – the developer then has to make the report along with the planning application public and send it to the relevant authorities for review.

The general public and other interested organizations are then given the opportunity to comment on the impacts of the project.

  • Decision-making – after the public consultation, the relevant authority will then decide whether or not to give the project the go-ahead and comment on the significance of the environmental effects.
  • Information on consent – the public will then be made aware of the decision to approve the project.
  • Monitoring – once the project is given the go-ahead the developer must monitor the impact of the project during its construction and operation phase and evaluate the measures it has taken to mitigate negative environmental impacts.

How to know if an Environmental Impact Assessment is needed?

Known as the screening stage, once an application is submitted for approval, a decision will normally be taken by the national government or the relevant authorities (dependent on individual countries).

Under EU law, some types of public projects always need to do an environmental impact assessment, for example, major power plants and major transport infrastructures such as large highways and railway lines.

what is an environmental impact assessment

For other types, an environmental impact assessment must be done if the project is likely to have a significant environmental impact, but what does this mean exactly? What is a significant impact?

Luckily, the EU has a set of questions that can be used as a guide to check if an environmental impact assessment is necessary for instance;

  • Will there be a large change in environmental conditions?
  • Will new features be out-of-scale with the existing environment?
  • Will the effect be unusual in the area or particularly complex?
  • Will the effect extend over a large area?
  • Will there be any potential for transboundary impact?
  • Will many people be affected?
  • Will valuable or scarce features or resources be affected?

If the answer to any of the questions is yes then an environmental impact assessment will have to be done. If the answers to any of the questions are uncertain then it is likely an environmental impact assessment will be needed to determine significance.

A list of all the questions can be viewed here.

The location of the project is also an important factor, if the project will take place in or nearby an environmentally sensitive area such as a nature reserve an EIA will probably be needed.

Broadly speaking the 3 main factors that determine if a project needs screening are the type or nature of the project, its size and its location. Larger scale projects are most likely to need an EIA given the often irreversible longer-term impacts on the environment and people’s lives in the surrounding area.

The decision on whether a project needs an EIA must be publicised so that the community is made aware and can respond accordingly.

What Types Of Info To Include In An Environmental Impact Assessment?

The scoping stage is the part of the process where the content of the report needs to be determined, i.e what type of data should be included and what impacts need to be investigated.

Basically, this stage is all about determining relevant information which is important for the developer so no time is wasted on unnecessary issues. Scoping is also crucial to ensure that all relevant information is included and the most important impacts are studied so that the authorities can make an informed decision.

The applicant can submit a request to the national agency in charge to define the boundaries of the assessment. In most countries this is optional and a scoping decision is only provided upon request by the applicant/developer.

However, the scoping stage is considered to be good practice and so is something that developers should consider. Also, the developer can choose to consult relevant bodies such as local environmental agencies.

The EIA Report

Once the scope of the assessment is decided, the data can be collected and the report prepared. The report is the material evidence of the EIA process if you will.

The report has to communicate with two different audiences, the decision-makers and the people impacted by the project. So, it needs to be written in a clear and organised way with a logical structure that is easy for non-experts to understand.

It also should include a baseline or do nothing scenario describing how the environment in the target area would develop without the project. In some cases, this is not needed if the project is deemed essential as could be the case for some waste management proposals.

What are the alternatives?

A feature of most EIA reports is the identification and consideration of alternatives to the proposed project.

One of the most important features of an EIA is the inclusion of a non-technical summary. This part of the EIA should steer clear of any technical jargon and be easy to understand for people who have no environmental expertise and are not familiar with the project.

Once the report has been submitted to the decision-makers and the necessary stakeholders are given the opportunity to voice their comments, then the decision of whether to approve the project will be announced.

Who Is Involved In The Consultation Process?

The EIA Directive requires three different groups to be consulted on the findings in the report. They are:

  • The wider public (a public consultation should be a minimum of 30 days)
  • The relevant authorities such as local planning authorities or environmental agencies.
  • Other member states (if the report has identified transboundary impacts).

Who Reviews The EIA And Grants Approval?

This is dependent on national governments with some such as the Netherlands opting for an official commission of experts.

What Happens Next? The Monitoring Stage

Once the project is given permission to go ahead, the developers are still required to monitor the environmental impacts during project implementation and operation.

These evaluation plans must have been clearly described in the EIA report.

Monitoring measures usually include methods such as indicators and specific criteria to assess focus areas, for instance, energy used in the project life cycle or types of pollution emitted.

environmental impact assessment meaning

‘Monitoring need not be difficult or overly technical, and could even be as simple as a photo taken from the same vantage point over time if such a photo clearly documents the relevant indicator’.

EU guidelines on EIA 2017

Monitoring is needed to document the longer-term impact of the project on communities and the environment.

Let’s Recap

An EIA is used to factor in the environment early on in a project. It’s a vital tool for sustainable development and helps to prevent permanent environmental damage.

Protect our natural resources – Doing an environmental impact assessment helps a project run more smoothly. It gives developers the chance to identify potential problems that could occur along the way and come up with solutions. Developers are more prepared and ready to respond.

More proactive less reactive – By giving communities and others a chance to voice their opinions, an environmental impact assessment enables more transparency in the decision-making process. Creating a dialogue between developers, local authorities and communities can improve relations, reducing the risk of conflict further down the road.

More inclusive – So, while the environmental impact assessment process can seem daunting at first, breaking it down step by step makes it easier to get to grips with.