In this article, we consider the social effects of a large dam in the Eastern Pyrenees region of France. In 1976, the French state constructed a dam near the town of Vinça on the Têt River, altering the hydrological conditions that had co-produced a complex system of hydro-social relations evolved since the Middle Ages. We argue that through altering the relative proximity of dependencies between farmers and between farmers and the state, the dam has had the effect of transferring expertise and social power from local to central authority. However, this shift is made difficult by the evolution of local farmers associations to take advantage of the new hydrological circumstances produced by the dam. The production of hydrological certainty assured by the dam has changed the raison d'etre for these associations (known as Association Syndicale Autorisée), providing them with new opportunities such as in the development of pressurized drip irrigation. In these circumstances, the relations between the Association Syndicale Autorisée and the state produce a hybridized authority over water, neither quite centralized nor local but combining both. We draw from Bookchin's elaboration of 'post-scarcity anarchism' as well as Bouba-Olga and Grossetti's concept of proximities to describe the pitfalls and the promises of pressurized irrigation in the region, made possible by the dam.