Monitoring effectiveness of the EU Nitrates Directive Action Programmes. Results of the MonNO₃ workshop in the Netherlands 11-12 June 2003

The contributions of the participants to the MonNO3 workshop, organised by RIVM, GEUS and DMU in The Hague (Scheveningen), the Netherlands on 11-12 June 2003 are assembled in this report. More specifically, the report provides a synthesis of the papers and an outline of the workshop discussions on the methodology for monitoring the effectiveness of the EU Nitrates Directive Action Programmes. The legal requirements for this type of monitoring have been incorporated in Article 5(6) of the Nitrates Directive. Two different approaches −upscaling and interpolation− for describing the effect of Action Programmes on a national scale were defined but not discussed in detail, since this was beyond the scope of the MonNO3 workshop. All contributions presented make clear that water quality is not only influenced by agricultural practice but by other factors as well. Soil type, hydrological and geological characteristics of sediments or rocks (or of the surface water system), and climate and weather are examples of environmental factors that may cause differences in water quality, either between locations or in time.