Résumé
The decentralisation of water management in France is a result of a necessary reform of former State management of water and a general trend towards local authorities integration in policy formulation and application. The former top-down management gives now place to a management based on policies defined in a progressive way, at different nested levels, designed at the scale of the resource. At each level, the decision is made by a commission of representatives of users, local authorities and the State. It gives a frame and key values that will be used by underlying levels An example of this reform is the low water management in the Adour River basin, located in the Southwest of France. The massive growth of irrigation led to a net deficit of water in the Basin. The idea that rivers drying are no longer acceptable has been expressed more and more strongly. To cope with that deficit, a framework of commissions and tools has been set up : SDAGE at the Adour-Garonne region level, Low Water Management Plan (PGE), currently in negotiation among all stakeholders, at the Adour level. It will settle for all the affluents and Adour River parts: (i) key values for low water river flows and (ii) areas and water volumes that can be dedicated to irrigation. This scheme allows a management at the scale of the resource and is supported by a large majority of stakeholders. Nevertheless, this Plan encounters the scepticism of the Ministry of Environment because of the possible lack of strength of environmentalist actors throughout the negotiation. More generally, this evolution brings along some unresolved questions : definition of common interest, elicitation and weight of each stakeholder, coordination between different water management levels, financing of water management. Three questions are currently studied by the Irrigation Research Unit of CEMAGREF in an economic approach: (i) the acceptability of reforms by stakeholders, (ii) the impact of decision mechanisms on negotiation issues and (iii) the way the State implements contracts with water users.