Assessing the likelihood of significant effects
A likely significant effect is, in this context, any effect that may reasonably be predicted as a consequence of a plan or project that would negatively and significantly affect the conservation objectives established for the habitats and species significantly present on the Natura 2000 site. This can result from either on-site or off-site activities, or through combinations with other plans or projects. It should be recalled here that if likely significant effects cannot be excluded beyond reasonable doubt, the plan or project will have to undergo a full appropriate assessment under Article 6(3) (see section 3.2.2.b for further details on assessing potential impacts). Significance of the effects will vary depending on factors such as the magnitude of impact, the type, extent, duration, intensity, timing, probability, cumulative effects and the vulnerability of the habitats and species concerned. Box 7 lists examples of indicators to quantify the significance of these effects. Sources of information to assess the significance of effects include evidence from similar operations affecting sites with similar designated features in a similar conservation condition or with similar conservation objectives, and expert judgement based on available evidence. However, as each case is necessarily different, consideration must be given to the local circumstances. The assessment must therefore always be done on a case-by-case basis. As stated in the Article 6 Guide, what may be significant for one site may not be significant for another. For example, a loss of a hundred square metres of habitat may be significant for a small rare orchid site, while a similar loss in a large steppe site may be insignificant if it does not affect the site’s conservation objectives. In case of plans, depending on the level of definition and details of the various aspects and components of the plan, it may be difficult to assess the magnitude and significance of all potential effects on individual sites at this stage. Nevertheless, the likelihood of significant effects on Natura 2000 site can still be assessed for instance in light of the type of plan or project and its potential zone of influence. Plans must therefore be screened with a sufficient degree of caution (beyond reasonable doubt), and in light of the precautionary principle, to avoid ruling out components or actions with a potential impact on a Natura 2000 site and excluding them from further scrutiny in the appropriate assessment. As regards the assessment of mitigation measures (18) in implementing the Article 6(3) procedure, the Court has ruled that ‘in order to determine whether it is necessary to carry out, subsequently, an appropriate assessment of the implications, for a site concerned, of a plan or project, it is not appropriate, at the screening stage, to take account of the measures intended to avoid or reduce the harmful effects of the plan or project on that site’ (Case C-323/17). However, project developers can sometimes design projects in a way to avoid or minimise potential impacts from the outset. This can be done by using best available technologies or by applying pre-emptive measures, including statutory measures (e.g. no go zones) prescribed e.g. in sector-specific regulations, Natura 2000 management plans or in spatial/zoning plans Such generic components of the project can be considered in the screening, contrary to the plan- or project-specific mitigation measures that must not be taken into account at this stage. These components should be clearly identified in the project description. Specific mitigation measures e.g. construction of green bridges to allow migration of species for protection of which the site has been designated, particularly if imposed by the competent authority, should only be considered during the appropriate assessment, as described in section 3.2.5.
Source: EUR-Lex (Cellar) · retrieved 2026-09-25 · Text as adopted (Official Journal); later amendments are not incorporated in this text.