A century after the first global attempt to regulate hydropower in transboundary waters, states continue to struggle to balance human, nature and energy needs. Emerging economies rely on hydropower as an affordable and clean energy for sustainable development, often without understanding its challenges and best practices. This paper examines the evolution of the universal legal regime on hydropower, analysing global freshwater legal frameworks and specific regulations applicable to the La Plata River Basin. This illustrates the importance of the progressive development of global, regional and basin agreements to effectively governing transboundary waters and hydropower.