Chile’s neoliberal central water management gives shape to a series of conflicts arising from diverse understandings and ways of life linked to water. This article addresses the question of who is responsible for the ecological costs regarding water use of mining activity in the north of Chile. From the perspective of hydro-social territories, we analyze how the local population in Tarapacá is acting on unequal footing regarding environmental information and knowledge. Local and practical experiences are devalued against technical and scientific modeling, supported by legal and political definitions of “the environment” and “water”. Focusing on diverse local narratives, we show how the local population feels threatened by the environmental impacts of mining activity but struggles to find legitimate ways of articulating those anxieties to gain a sense of agency. We conclude that the local ecological consequences of extractivism in this region can only be understood in the context of the wider legal and economic framework regulating the appropriation of water as a resource and that long-term efforts in more participatory sociohydrological modeling might help to broaden the knowledge base for contested decision-making.