In the South of France, gravity-fed irrigation canals embody centuries-old experience in water management in response to the high variability of rainfall across space and time. But nowadays, the sustainability of these works (called "béals" in the Cévennes gardoises) is no longer given and their very existence comes in the way of the adaptation to the new regulations concerning water sharing and quality (water laws 1992, 2006). To address a situation that has become problematic, a process of modernisation (institutional and technical) of the canals has been initiated by the Administration. Based on fieldwork in the Cévennes with irrigators' associations dealing with the modernisation of their béals, the aim of this paper is to discuss the actors' relationship to water through the study of local reactions to, and questions about, an administrative conception of these works that denies the values and knowledge associated with them.