This paper synthesises the objectives, methodologies and results of my PhD thesis. As we observe the resurgence of dam building throughout the world, this research analyses the representations of dams and their spatial and temporal trajectories. Building on the literature of social and cultural geography on representation, and the writings of political ecology on discourse, the thesis confronted different sources (newspapers, interviews and archives), study areas (in France and Australia) and methodological approaches (quantitative and qualitative) in order to follow the discursive evolution of hydraulic infrastructure. The points of view of various stakeholders were also considered: inhabitants, engineers and hydraulic institutions, opponents to dams, administrations in charge of nature protection and scientists who produce environmental knowledge. From a methodological perspective, the dissertation highlights the limits in using certain material and illustrates the necessity to consider different sources in parallel. The results show the evolution of waterscapes, hydrosocial spaces and cycles – the gradual concessions made to environmentalists at the expense of hydraulic bureaucracies – but they also illustrate, on a broader perspective, the production and the flow of discourses on the environment – the decline of a Promethean discourse on nature and the multiplication of different and sometimes opposing representations of the environment – particularly during conflicts and controversies.