AbstractThis paper presents a holistic strategy on the interaction of activities in the Elbe river basin and their effects to eutrophication in the coastal waters of the German Bight. This catchment - coastal zone interaction is the main target of the EUROCAT (EUROpean CATchments, catchment changes and their impact on the coast) research project, with the Elbe being one of eight case studies. The definition of socio-economic scenarios is linked with the application of models to evaluate measures in the catchment by estimation of nutrient emissions with MONERIS (MOdelling Nutrient Emissions in RIver Systems) and their effects on coastal waters with the ecosystem model ERSEM (European Regional Seas Ecosystem Model). The cost effectiveness of reduction measures will then be evaluated by application of the CENER model (Cost-Effective Nutrient Emission Reduction) and a multicriteria analysis. Finally, the interpretation of ecological integrity is used as a measure to describe ecological impacts in an aggregated form.