We analyze environmental impact assessment (EIA) for infrastructure development projects in Latin America through the case of the "El Cercado" dam on the Rancheria river in La Guajira Province of northern Colombia. We argue that social and environmental conflicts regarding development projects are not only the result of deficient EIA implementation but also of historically established power relations and deep-rooted beliefs concerning the economy and socio-spatial relations, of which EIAs are a constituting and enabling element. We focus on governmentality practices from an ethnographic political ecology perspective to trace how the EIA uses the concept of "areas of influence" as a standardized inclusion/exclusion technique, limited by its static nature and functioning as a legitimizing device for governmental interest to expand neoliberal economies in natural resource-strategic regions. Our analysis aims to understand how EIAs used for infrastructure development projects in Latin America have failed to prevent socio-environmental conflicts. At the same time, we question the notions of "space", "influence", and "affected population" behind EIA practices. We conclude that EIAs are a government technology of neoliberal environmental governance that has the potential to exclude the socio-spatial dynamics of local populations while depoliticizing the interests behind the project. With this article, we contribute to the ethnographic approach to governmentality in the context of infrastructure development projects in Latin America and to the understanding of the role of expert knowledge and technologies of government in neoliberal hydro-politics.Keywords: Environmental Impact Assessment, dam, hydro-politics, government technologies, social conflict