§3.1.4 Step 4: Assess whether likely significant effects can be ruled out in view of the site's conservation objectives

The next step of the screening stage is to assess the likelihood and potential significance of the impacts identified in the previous step, taking into account potential cumulative impacts with other plans or projects. 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. Box 7 Examples of significance indicators Impact type Significance indicator Loss of habitat area Degradation Hectares of habitat lost, percentage of the habitat lost Area (in absolute terms and percentage) where the attributes used to determine the conservation status of the species or habitat has worsened as well as the scale of degradation for each of the attributes Disturbance Degree of intensity, duration or permanence of the disturbance factor, its distance from breeding areas Fragmentation Change in comparison with the original and desired states (e.g. creation of several small habitat patches instead of one large one, hectares of habitat exposed to the edge effect) Indirect effects Degree to which the area is opened to other threats (invasive alien species, human and animal penetration, additional developments). 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. Assessing possible cumulative impacts with other plans and projects During screening, the assessment of the likelihood of potentially significant effects should be done of the plan or project, either alone or in combination with other projects or plans. The assessment of such cumulative impacts is often less detailed at the screening stage than in the appropriate assessment. But there is still a need to identify all other plans or projects that could give rise to cumulative impacts with the plan or project in question. The ‘in combination’ screening requires the identification of other plans and projects that can have potential effects on the same Natura 2000 sites and then assessing their capacity to cause significant effects when considered together with the plan or project under assessment. If this analysis cannot reach definitive conclusions, it should at least identify any other relevant plans and projects that should be scrutinised in more detail during the appropriate assessment. Assessing cumulative effects at the screening stage A series of individually low-level impacts may, in combination, produce a significant impact. When determining likely significant effects, the combination with other plans and/or projects should also be considered to take account of cumulative impacts during the assessment of the plan or project. The in-combination provision concerns other plans or projects that have been already completed, approved but uncompleted, or proposed (i.e. for which an application for approval or consent has been submitted). In addition, it is important to note that the assessment of cumulative effects is not restricted to the assessment of similar types of plans or projects covering the same sector of activity. All types of plans or projects that could, in combination with the plan or project under consideration, have a significant effect, should be included during the assessment. Similarly, the assessment should look at the cumulative effects, not just between projects or between plans but also between projects and plans (and vice versa) . For example, a new project to build a major motorway may on its own not adversely affect the site, but when considered in combination with an already approved housing development plan for the same area, the impacts may become significant enough to adversely affect the site. By contrast, a plan may have no significant impact on Natura 2000 sites on its own but may be assessed differently if considered in combination with an already proposed or authorised major development project not included in that plan. See further details in the Article 6 Guide – section 4.5.3. Obtaining information on other plans and projects that can combine to generate cumulative impacts on the Natura 2000 site can be challenging. It is very useful to have databases or information systems that can provide this information in a selected area, as some countries already have or are in the process of developing (19). Existing databases to inform the public about SEA and EIA of plans and projects may also be used to identify possible cumulative effects (20). In any case, the competent authorities (environmental or sectoral) should be consulted and should be able to provide information about other plans/projects to consider during the screening. Table 2 outlines the key steps for assessing cumulative effects on a Natura 2000 site. Steps in the assessment Activity to be completed Define geographic boundaries and the timeframe for assessment Define boundaries for examining cumulative effects; note these will be different for different types of impact (e.g. effects upon water resources, noise) and may include remote (off-site) locations. Identify all projects/plans that could act in combination Identify all possible sources of effects from the plan or project under consideration, together with other sources in the existing environment and other possible effects from other proposed projects or plans; timing and phasing of projects or plans. Impact identification Identify the types of impact (e.g. noise, water resource reduction, chemical emissions) that can affect the structure and functions of the site vulnerable to change. Pathway identification Identify potential cumulative pathways (21) (e.g. via water, air; accumulation of effects in time or space). Examine site conditions to identify where vulnerable aspects of the structure and function of the site are at risk. Prediction Predict the magnitude/extent of identified likely cumulative effects. Assessment Explain whether or not the potential cumulative impacts are likely to be significant, taking into account information collected during the ‘assessing significance’ step. When a protected habitat or species in the site is already in an unfavourable condition or when critical thresholds of impacts for the habitats’ or species’ specific attributes are being exceeded (or if the site is subject to cumulative effects that will lead to either of these states), any additional plan or project which, either alone or in combination, adds further impacts to these levels is likely to have a significant effect on the Natura 2000 site.

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Source: EUR-Lex (Cellar) · retrieved 2026-09-07