1This dissertation contributes to the literature on power relations within irrigation management. Drawing on a corpus of critical studies showing how irrigation is linked to social relations of power, it shows how there is a lack of analytical precision in connecting macro- and micro-levels of analysis on this topic. From a hydro-social perspective on irrigation management, this work develops a Foucauldian analysis of participatory irrigation policies to breach the analytical gap with the more anthropological approach of Irrigation Studies. The theoretical objective is then to refine the understanding of the relational dimension of power in the intricate social, technical and hydrological reality of irrigated perimeters. The case study is situated in the eastern plains of Nepal, on the country’s biggest irrigation system. By seeking to understand the effects of these policies on a pre-existing hydro-social territory, this dissertation explores the encounter between the model of the water user association – bearer of its own logics of power–, and the traditional power relationship, that is patronage. In order to better explain the effects of this encounter on local farmers’ livelihoods, this work develops conceptual tools based on a critical realist approach. These tools highlight processes of reflexivity, criticism and ruptures in the social hierarchy, generating different but simultaneous social reconfigurations on a scale of the irrigated perimeter and beyond. By passing field data through the filter of these concepts, this dissertation shows how a participatory irrigation system is essentially political in the sense that it favours a reproduction of pre-existing power relations, while opening up the potential to modify them. Though elite capture of water user associations is evident, the temporal and spatial spread of participatory institutions over a territory is often under-analysed, and thus underappreciated as a lesson for future policy-making. This work therefore concludes on the need to assume the political dimension of irrigation in order to allow future versions of irrigation policies to reconfigure power relations to the benefit of the people excluded from irrigation management.