Ultimate Guide to Environmental Impact Assessment (EIA) in Ireland: Your Complete Planning and Compliance Resource

Introduction to Environmental Impact Assessment (EIA)

Environmental Impact Assessment (EIA) is a legally defined process used to evaluate the likely significant environmental effects of certain public and private projects before development consent is granted. In Ireland, EIA is integrated into the planning system under the Planning and Development Act 2000 (as amended) and implements the Environmental Impact Assessment Directive (2011/92/EU as amended by 2014/52/EU).

EIA ensures that decisions regarding development consent are made with full knowledge of a project’s likely impact on the environment, including human health, biodiversity, and cultural heritage.

What is an Environmental Impact Assessment Report (EIAR)?

An Environmental Impact Assessment Report (EIAR) is defined under Irish law as:

“a report of the effects, if any, which proposed development, if carried out, would have on the environment and shall include the information specified in Annex IV of the Environmental Impact Assessment Directive.”

The EIAR is prepared by the developer and forms part of the consent application submitted to the Competent Authority (CA). It enables the CA and the public to understand the likely significant environmental effects of a proposed project and informs the decision-making process.

Legal Framework

Step-by-Step Method for Preparing an EIAR (Environmental Impact Assessment Report)

The following steps outlines how to prepare an EIAR.

Step 1: Screening – Is an EIA Required?

Purpose: Determine whether the proposed project falls under categories requiring a mandatory EIA or if it needs a screening determination.

• Check relevant thresholds and criteria under the Planning and Development Regulations 2001 (as amended).

• If there is uncertainty, submit a request to the Competent Authority (CA) for a formal screening determination.

• Outcome: Decision whether an EIA is legally required.

Step 2: Scoping – What Should the EIAR Cover?

Purpose: Identify the key environmental issuess to be addressed in the EIAR and what methods should be used to gather and assess that information.

• Engage in early consultation with the CA and prescribed bodies.

• Use the results of consultations and baseline knowledge to determine significant environmental factors

  • Environmental factors include material assets (e.g. Roads & Traffic, Built Services, Waste Management), water (e.g. surface water, ground water, waste water), and landscape (e.g. visual effects and amenity).

• Focus on likely significant effects, not all possible effects.

• Optional but strongly recommended to seek a formal scoping opinion from the CA.

Step 3: Consideration of Reasonable Alternatives

Purpose: Demonstrate how environmental considerations influenced project choices.

• Describe reasonable alternatives studied by the developer, including:

  • Alternative sites

  • Alternative designs

  • Technologies or layouts

  • Project timing or scale

• For each alternative, explain why it was chosen or rejected, taking environmental impacts into account.

• Must include the “do nothing” scenario as a baseline (aka a general description of the evolution of the key environmental factors of the site and environs if the proposed project did not proceed).

Step 4: Project Description

Purpose: The developer clearly and objectively describes the proposed development.

Include:

• Location and layout

• Physical characteristics (e.g., structures, emissions, materials)

• Operational details (e.g., duration, processes, energy use)

• Land use requirements

• Resource consumption (e.g., water, raw materials)

• Residuals, waste and emissions

• Construction, operation, and decommissioning phases

Ensure the description is detailed, consistent, and legally accurate.

Step 5: Baseline Description – The Receiving Environment

Purpose: Describe the current state of the environment (baseline scenario) before the project is implemented. This involves the collection and analysis of information on the condition, sensitivity and significance of relevant environmental factors that would be significantly affected by the project.

Organise this section by the following environmental factors (as required by Article 3 of the EIA Directive):

• Population and human health

• Biodiversity (with special focus on species/habitats protected under Directives 92/43/EEC and 2009/147/EC)

• Land, soil, water, air, and climate

• Material assets, cultural heritage, and the landscape

• Interactions between all the above

Use:

• Up-to-date and verifiable data

• Maps, diagrams, surveys

• Reliable and replicable scientific methods

Step 6: Assessment of Likely Significant Impacts

Purpose: Identify, describe, and present an assessment of the direct and indirect effects of the project on the environment.

Key considerations:

• Magnitude, duration, frequency, reversibility of effects

• Effects during construction, operation, and decommissioning

• Cumulative effects with other existing or approved projects

• Use clear and consistent terminology to describe impact significance (e.g., slight, moderate, significant)

• Ensure assessments are evidence-based and repeatable

Step 7: Mitigation and Monitoring

Purpose: Describe how adverse impacts will be avoided, prevented, reduced, offset, or monitored.

• Identify mitigation measures for each significant effect.

• Include design changes or technologies incorporated to reduce impact.

• Describe monitoring programmes to ensure mitigation effectiveness.

• Clearly assign responsibilities and timing for implementation.

• Where appropriate, include contingency plans for unforeseen impacts.

Ongoing: Consultation Throughout the EIAR Process

Consultation is not a separate step — it must occur throughout.

• Engage with:

  • Statutory consultees (as required under legislation)

  • Non-statutory stakeholders and the public

• Consultation helps to:

  • Identify issues early

  • Improve design and mitigation

  • Build transparency and trust

Include a Consultation Section in the EIAR that documents:

• Who was consulted

• When and how they were consulted

• Summary of feedback

• How issues raised were addressed in the EIAR

Final Structure of the EIAR

To align with legal expectations, the EIAR should include:

1. Non-Technical Summary (NTS)

2. Introduction and Methodology

3. Project Description

4. Consideration of Alternatives

5. Description of Receiving Environment

6. Assessment of Impacts

7. Mitigation and Monitoring Measures

8. Consultation Summary

9. Cumulative and Interactive Effects

Note: the EIAR, or sections of the EIAR, should avoid including a ‘Conclusions’ Section. Instead, the EIAR can include an overall summary of the effects on the environment.

Structure of the Environmental Impact Assessment Report

The EIAR’s structure and language should have the following:

• A rational, systematic, format which clearly shows how it relates to mandatory requirements.
• Accessible and clear.
• Ensure that facts and prediction are kept separate.
• FORMAT:
  • Starts with an introduction
  • Descriptions of the screening and scoping stages
  • An overall project description.
  • Examines each environmental factor as a separate section.
  • Clear page numbering and numbering of sections and subsections.
  • Include a table of contents with lists of tables, figures, and appendices.
• LANGUAGE:
  • Thorough briefing and editing to reduce the possibility of inconsistencies. 
  • Avoid euphemisms
  • Consistent terms
  • Avoid repetition
• ILLUSTRATIONS: Maps, plans, sections, diagrams, photographs and sketches can be used.
• APPENDICES: Can be used for supporting information to offer a more detailed understanding of significant issues.
• SIZE: Varies due to the range and complexity of significant issues.

It must also be:

• Prepared by competent experts

• Objective, systematic, and clearly structured

• Legally defensible and capable of supporting a robust decision by the competent authority

Fundamental Principles of the EIA Process

Effective EIA involves:

• Anticipating and avoiding significant effects

• Maintaining scientific objectivity

• Ensuring clarity and quality of information

• Providing relevant and legally compliant data

• Facilitating meaningful consultation

These principles aim to protect the environment, improve project design, and inform better decision-making.

Next Steps of the EIA Process

After preparing the EIAR, the next steps include submitting the report to the Competent Authority for review, followed by public consultation and feedback. The authority will then assess the findings, consider mitigation measures, and make a decision on development consent, ensuring environmental protection throughout.

Further Resources

• Environmental Protection Agency (EPA): www.epa.ie

• Department of Housing, Local Government and Heritage: www.housing.gov.ie

• European Commission – EIA Directive: ec.europa.eu/environment/eia

Final Notes

This guide is based on official Irish guidance and the requirements of the EIA Directive. For project-specific legal compliance, developers and planners should refer to the EPA Guidelines on EIARs, the Planning and Development Regulations, and consult with the competent planning authority.