In 1957 the establishment of the Mekong Committee was the first ever involvement by the United Nations (UNECAFE, now UNESCAP) in cross-border river basin planning, its purpose was to embark on a large-scale irrigation and five-dam hydropower project, the Development of Water Resources in the Lower Mekong Basin (Jacobs 2002). Only one dam, the Nam Ngum, was the outcome of intergovernmental cooperation, however, as the four riparian countries (Thailand, Laos, Cambodia and Vietnam) did not give their consent to other projects involving cross-border agreements. In 1975 attempts to rejuvenate cross-border efforts took the form of a Joint Declaration of Principles for Utilization of the Waters of the Mekong Basin that prohibited the “unilateral appropriation” of water without “prior approval” and “extra-basin diversion” without unanimous consent.