What role can non-diplomats play in managing and altering power relations in transboundary river basins? We answer this by investigating the lobbying eff orts of indigenous peoples to stop the construction of the planned Orokawe (Baynes) dam on the Kunene River. The Kunene River forms part of the border between Angola and Namibia with several concluded treaties in place. These treaties set the context of bilateral state diplomacy concerning the allocation and management of a transboundary water resource. The theoretical foundation of our investigation are ideational power conceptualizations and practice theory. We discuss the employment of ideational power in transboundary rivers with numerous practices, such as lobbying and transnational network development. This article argues that actors consciously practice power during transboundary water diplomacy.