In the last decades, Europe became ever more aware of the fact that it has to respond to its own "water crisis". Facts and figures indeed demonstrate clearly that Europe water resources are under heavy pressure: 20% of surface water is at serious risk from pollution, 60% of the cities over-exploit their groundwater resources and in addition to this, the region has to cope with an ever-growing demand for water. As a response to these concerns, the Europe region has come up with new tools to manage and protect water. In particular, the European Union has adopted in 2000 a new legislative approach through the Water Framework Directive (WFD). The Directive sets an ambitious goal to its Member States: the achievement of the good status of European water bodies by 2015. Identifying challenges to (and solutions) for its achievements has to be recognized as a top-priority target.