Through dialogues between partners, a river contract intends to develop and restore the multiple functions and uses of water in answer to the needs of a community of users. Under this scheme, both government and private-sector players commit themselves by means of a contract to implement a consensus action programme to restore the river and its drainage basin’s water resources. Information and awareness campaigns are added to concrete actions of waterway development and different sorts of work connected to water. The river committee is a place for democratic speech where the familiar rubs shoulders with the institutional, where citizens meet operators, where the life forces of society are finally brought together to take charge of their river’s future and their relationship with the river. In this way, a joint project has been bringing together Belgian and French protagonists since 1999, trough the Interreg II and Interreg III operational programmes. They work now together in a joint management of the river and its tributaries, this time on the scale of the entire Semois-Semoy hydrographical subdrainage basin. This article describe the concept and the methodology of this concrete transboundary collaboration, the results and the perspectives.