Through their strategic and programmatic role, master plans should constitute a framework that guides projects towards both a better understanding of reduction measures and a consistent implementation in their territory. Where the planning document contains prescriptive conditions, mitigation measures should be incorporated to ensure they are implemented.
Reduction of environmental impacts at a master plan level can be context dependent and may include either direct measures to reduce the impact, or a general framework to study and limit the impact of the master plan on the environment. For instance, in France, the Schéma Directeur d’Aménagement et de Gestion des Eaux (SDAGE) is a strategic document for the implementation of the Water Directive. It specifies the fundamental guidelines for each major French river basin to promote balanced management of water resources amongst all users (citizens, farmers, industry). SDAGE also establishes guidelines for reducing the impact of development projects such as transport infrastructure on aquatic and wetland environments. Some guidelines of the SDAGEs ask project owners to seek ‘technical alternatives’ to their projects when they impact environs with high environmental stakes (e.g., wetlands, watercourses in very good condition, biological reservoirs, major migratory routes, habitats of species protected and endangered species); otherwise their project will be incompatible with the SDAGE.
For a given policy, objective or for a project implemented within the scope of the master plan, appropriate biodiversity mitigation frameworks or approaches should be considered. These can include eco-design, reduce management requirements of natural or agricultural areas, environmental requalification, environmental upgrading with the restoration of ecological continuity, or exemplary construction site taking into account natural environments. For instance, the decision-making process related to the European Regional Development Fund (ERDF) operation program includes SEAs that should aim to formulate avoidance and reduction measures. For reduction measures, a general framework should be given to each project benefiting from ERDF financial support, such exemplary building sites, the identification of solid environmental management methods and engineering.