This study investigates Lebanese and American designs for hydroelectric infrastructure on Lebanon’s Litani river. Beginning in the late 1940s, Lebanese and American experts transformed the river by rendering it into statistical representations, seeking to redesign it from a complex biosphere into a machine producing economic growth and national unity. I draw upon methodologies from environmental history, science and technology studies, and the history of science to ask: What informed different kinds of calculation by different individuals and institutions? What can infrastructure tell us about the boundaries of science, finance, and nature? How might financial institutions demarcate good science from bad? The first section discusses development proposals submitted to the World Bank by two Lebanese planners, Ibrahim 'Abd al-'Al and Maurice Gemayel. The second examines a subsequent proposal submitted by the United States Bureau of Reclamation. Rather than evaluate these proposals according to absolute standards of good and bad science or sound and unsound design, this study explores how and why the World Bank made such demarcations in practice. The World Bank deemed the Lebanese proposals unacceptable and the Bureau’s satisfactory. I argue that this difference in acceptability emerged from three interrelated differences. Unlike the Lebanese engineers, the Bureau prioritized hydroelectricity over irrigation; established a boundary between the political and the technical in a manner that conformed to the World Bank mandate; and extended their calculations to the total economic inputs and outputs of the project, constituting a particular technocratic future for Lebanon. The Bureau’s calculations rendered the Litani into a machine that manufactured a single commodity: kilowatt hours. Calculating the total economic effects of that single commodity allowed the Bureau to calculate Lebanon’s future. Their calculations required that the Lebanese government legislate that a public utility purchase the all of the Litani’s kilowatt hours at a fixed price above market rate. The World Bank then constructed a regime of disciplinary debt that could compel the Lebanese government to make this and other legislation, ensure the durability of those reforms, and maintain the stability of the Bureau’s calculations into the future.