MULINO is an EU RTD project, funded under the FP5-EESD programme. It aims at providing aDecision Support System (DSS) targeted at solving decision problems in the management of water resources.Through the integration of socio-economic and environmental modelling techniques with geographicinformation system (GIS) capabilities and multi-criteria decision aids, the MULINO-DSS aspires to be anoperational tool which meets the needs of European water management authorities and facilitates theimplementation of the EU Water Framework Directive. The application-driven approach to developing theMULINO-DSS combines the scientific background of the consortium members with local knowledge anddecision support needs, expressed by five user groups. The diversity of cultural, socio-economic andenvironmental characteristics of the case studies requires that the tool is capable of a common approach todifferent decision cases but also flexible enough to adapt to the specific objectives and constraints of a givendecision problem. The DPSIR framework (Driving forces – Pressure – State – Impact – response) has beenchosen as the overall conceptual framework of the DSS. A demonstration of the first MULINO-DSSprototype is presented through an application example in the Vela catchment that belongs to the VeniceLagoon Watershed (north-east Italy). The decision act refers to the choice among alternative actions (publicworks) for the improvement of Vela’s water quality.