Major factor in the electricity production, the number of hydropower plants is still steadily growing worldwide. Besides, such facilities entail a whole range of effects. A sound and in-depth assessment of all the impacts arising from each new project is required. While sustainability assessment tools provide relevant instruments in this aim, as they enable the evaluation of aspects from various kinds, interrelations between the latter are frequently overlooked. Based on the available literature, we use the concept of the causal diagram to structure and represent hydropower impacts in a generic form through causal networks. We develop and present a series of ten causal diagrams, each focusing on one specific topic. Strongly interrelated, the diagrams highlight the close ties existing between the multiple aspects of hydropower and enable a clear understanding of such links. A plain grasp of the impact pathways is essential to gain a holistic and comprehensive perspective of the consequences ensuing from the implementation of hydropower facilities. This step is also crucial in identifying relevant and concrete measures to mitigate undesirable impacts. All in all, such causal diagrams are meant to be used as guidance and supportive tools by decision makers and concerned stakeholders.