Directive 91/676/EEC on pollution caused by nitrates from agricultural sources applies only where the discharge of nitrogen compounds of agricultural origin makes a significant contribution to the pollution, given the objective of the Community legislature, namely to reduce and prevent water pollution caused or induced by nitrates from agricultural sources, and the scope of the measures envisaged for that purpose by Article 5. The directive is in conformity with the principles that ‘the polluter pays’ and that environmental pollution should be rectified at its source.