This paper explores the transnational networks of hydraulic and economic expertise that shaped Egypt’s decision to build the High Dam. The High Dam project was part of a wider effort, led by the Free Officers’ regime, to undertake an ambitious social and economic transformation, guided by principles of economic independence and social welfare, and that was to be achieved through centralized planning. Conventional studies of the High Dam emphasize its expression of state-guided development and the centralization of state power and insist that authoritarian regimes like Nasser’s were motivated by ideological imperatives that compromised sound technical and economic judgment. By contrast, this paper investigates the appeal of the High Dam project by looking at a wider set of ideas and practices in water management, that were common to industrialized and developing countries alike. To provide a fuller account of these transnational linkages, this paper look specifically at two forms of knowledge that were most influential: river-basin development and economic statistics. The paper draws primarily on the writings of some of the experts that were involved in formulating the High Dam project in its early stages. I will examine the economic and technical arguments that they used to support the building of the High Dam and show how these differed from earlier twentieth-century arguments about river control and water supply.