Mega-dams are commonly designed, constructed, and implemented under governors’ rule and technocrats’ knowledge. Such hydraulic infrastructures are characteristically presented as if based on monolithic technical consensus and unidirectional engineering. However, those who are affected by these water interventions, and eventually governed by the changes brought by them, often dispute the forms of knowledge, norms, morals, and operation and use rules embedded in mega-hydraulic engineers’ designs. Protests may also deeply influence the design and development of the technological artifacts. By using approaches related to the Social Construction of Technology and Partha Chatterjee’s politics of the governed, this article shows (i) how protests against the Baba dam in coastal Ecuador greatly influenced the dam’s designs, protecting communities’ lands from being flooded; and (ii) how, at the same time, techno-political decision-makers deployed hydraulic design as a dividing rule, turning potentially affected communities against each other. We conclude that megadam designs are shaped by the power interplay among governors and governed, with the latter being internally differentiated. By critically analyzing the role of technology development—materializing changing ‘political context and relationships’—we show how contested and adapted dam design may favor some stakeholders while simultaneously affecting others and weakening united dam-resistance movements.