Habitats Regulations Appraisal (HRA): likely significant effects

Checking for the likelihood of significant effects on Natura sites is a simple but precautionary part of Habitats Regulations Appraisal 

Checking for likely significant effects removes from the Habitats Regulations Appraisal (HRA) process any aspect of a plan or project that either:

  • clearly has no ecological connectivity to the site’s qualifying interests
  • obviously won’t undermine the conservation objectives for the qualifying interests to which it has a connection

This check:

  • should be a relatively quick and straightforward decision
  • includes plans and projects at any distance beyond the European site’s boundaries

You should only conclude ‘likely significant effect’ on the basis of reasonable links between a proposal’s effects and the site’s qualifying interests.

Reasoning must be provided in the HRA record to justify all conclusions made at this stage.

The competent authority must carry out an appropriate assessment for all remaining aspects of the plan or project. This includes any aspect where there’s reasonable doubt over the nature or size of its effects.

How to interpret ‘likely’ and ‘significant’

Unless a significant effect can be objectively ruled out with certainty, it is considered ‘likely’.

It was the Waddenzee case (European Court of Justice C-127/02) that clarified what “likely to have a significant effect” means in the HRA context. The European Court of Justice ruled that a plan or project should undergo an appropriate assessment “if it cannot be excluded, on the basis of objective information, that it will have a significant effect on the site”.

The Sweetman case (European Court of Justice C-258/11) reinforced and further refined the Waddenzee case interpretation. The Advocate General’s Opinion stated: “the question is simply whether the plan or project concerned is capable of having an effect. It is in that sense that the English ‘likely to’ should be understood.”

European Commission Managing Natura 2000 Sites guidance states that deciding what is and isn’t ‘significant’ requires an objective approach. But it also says that it requires an understanding of the “specific features and environmental conditions of the protected site concerned”.

You should therefore judge each case on its own merits: what may be significant for one site (or qualifying interest) may not be significant for another.

Note that following the UK’s departure from the European Union rulings from the European Court of Justice remain in force as though made by the Supreme Court.  We also continue to refer to EU procedural guidance for the management of European sites.

Cumulative effects

You must consider the effects of the plan or project ‘in combination with’ the effects of other plans and projects on the same European site. This is to check whether an effect that would not be significant, or likely, on its own might become significant, likely, or both when checked in combination with the effects of other proposals.

This test must consider both:

  • the potential effects of other plans published for consultation and projects seeking consent
  • any ongoing negative effects of completed plans or projects

Help and advice

Read further help and advice on Habitats Regulations Appraisal.

Find out more

Scottish Government policy for proposed SACs and proposed SPAs

Natura sites and the Habitats Regulations leaflet

Habitats Regulations Appraisal of Plans: Guidance for Plan-making Bodies in Scotland

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