Résumé
In the environmental field, the “functional” divisions in space that mark out areas for management are often presented as natural. The European Union thus frequently builds its macroregional strategies on natural characteristics by attaching them to mountain ranges, seas and of course river basins. The river basin and its European counterpart under the Water Framework Directive (WFD) enacted in 2000, the river basin district, do not escape this rule. This chapter examines the issues surrounding the construction and adoption of the natural spatial references – the catchment basin, the river basin district, and the body of water – in the implementation process of the WFD. Surface water is split into four categories: waterways, lakes and reservoirs, transitional waters and coastal waters.