Impact assessment is compulsory for plans and projects that may have an effect on sites of community importance (SCI) and special protection areas (SPA), established in accordance with the european directives
“Habitats” (92/43EEC) and “Birds” (79/409/EEC). Impact assessment is regulated in Italy by Presidential Decree 357/97 (art. 5 and Annex G), transposal of Directive 92/43/EEC “Habitat”, modified and integrated from Presidential Decree 120/2003. Art. 6 from Presidential Decree no. 120 determines that the territorial planning and programming must take into account the naturalistic-environmental value of the proposed sites of community importance (pSCI), Sites of Community Importance (SIC) and special areas of conservation (SAC).
The main purpose of Impact Assessment is safeguarding the integrity of Rete Natura 2000 through the analysis of the interferences of plans and projects not directly connected to the conservation of habitats and species for which they had been created, but capable of influencing their environmental balance. This kind of procedure is a preventive instrument aimed at obtaining the perfect balance between a “satisfying/satisfactory” conservation of habitats and species and the sustainable use of the territory. The proponent of the plan or program must submit a Study of Incidence/Impact to the competent authority for the interested sites, for which minimal contents the addresses in attachment G to Presidential Decree 357/97 are given. This attachment, which has not been modified by the decree (DPR 120/2003), states that the study of the assessment of the impact must include:

a detailed description of the plan or project that refers particularly to the type of actions and/or works, the dimension, the complementarity with other plans and/or projects, the use of natural resources, the production of waste, the pollution and environmental disturbance, the risk of accidents concerning the substance and technologies used;

an analysis of the interferences of the plan or project with the reference environmental system, taking into consideration the biotic and abiotic components and environmental connections.