This article traces the Misicuni dam project, which promised to solve water scarcity in the Central Valley of Cochabamba, Bolivia. First proposed in the 1940s, the project captured the popular imagination in the 1960s and 1970s, broke ground in the 1990s, and opened in 2017. The decisive impulse for the Misicuni dam project came from a broad democratic alliance of Cochabambinos that pressured the Bolivian state, international development banks, and contractors. This alternative history of vernacular modernism, or cross-class efforts to promote, participate in, and democratize modernist development, moves beyond the existing literature that assumes that outside political, economic, and technical elites impose modernist development projects like dams on communities from above. I argue that Cochabambinos' continued enchantment with the Misicuni dam project owed to the belief that the project's realization would fulfill the 1952 Bolivian Revolution's promise of a water-rich modernity without conflicts and competition over water.