Nitrates Directive
Zones rendered vulnerable by nitrates
While Member States have been granted “wide discretion” in the identification of vulnerable waters because of the complexity of the assessments which they are called upon to carry out in that context, they are obliged to respect the objectives of the Nitrates Directive, “namely, the reduction of water pollution caused by nitrates from agricultural sources”, so that “the exercise of that discretion may not result (...) in a large portion of nitrogen-bearing waters falling outside the scope of the Directive (Case C-258/00 Commission v France, paras. 53-54; Case C-356/13 Commission v Poland, paras. 38-42 (available only in French)).
Member States are not required to determine the proportion of the pollution which is attributable to nitrates of agricultural origin nor to establish that the cause of such pollution is exclusively agricultural. They must take into account not only pollution of agricultural sources, but also that of other sources, so as to determine a maximum level of pollution authorised for waters destined for human consumption (case C-293/97 H.A. Standley e.a. & D.G.D. Metson e.a.; case C-356/13 Commission v Poland (available only in French)). In other words, the mere fact that domestic or industrial discharges also contribute to the concentration of nitrates in superficial waters does not suffice as such to rule out as a possibility the application of Directive 91/676/EEC (case C-356/13 Commission v Poland). However, the Directive does apply only to the extent that discharges of agricultural origin contribute to the pollution in a significant way, even though the EU law does not provide a practical threshold. In addition, the above considerations do not imply that farmers should bear the costs of eliminating pollution to which they have not contributed (case C-293/97 H.A. Standley e.a. & D.G.D. Metson e.a.).
Mere powers given to an administrative authority to identify waters affected or potentially affected by pollution and to designate vulnerable zones is not sufficient for transposition and implementation of the Directive: “the identification of all waters that are affected by pollution or could be so affected (...), first, and, secondly, the subsequent designation, on the basis of the waters thus identified, of vulnerable zones, constitute distinct obligations which must be fulfilled specifically and separately” (case C-221/03 Commission v Belgium).