The World Bank‐funded Bisri Dam in Lebanon represents an emblematic case of a high‐modernist project that has foundered on a mix of hydrogeological recalcitrance, popular opposition and compounding crises. Examining the popular contestation surrounding the Bisri Dam, this article offers a socio‐ecological material lens on post‐colonial state building and the political economy of infrastructural failure. Avoiding the analytical impasse of crisis epistemes and heuristics of failure within the long tradition of development studies on the Global South in general, and Lebanon in particular, the article poses a number of questions. How are ‘crises’ and ‘failures’ constitutive of capitalist development, and for whom are they generative? How can the ubiquitous failures of the promises of infrastructure become an opportunity for the re‐animation, re‐appropriation and re‐politicization of hydrogeologies and political imaginaries? Rather than perceiving them as aberrations, the author argues that failures are constitutive of high‐modernist infrastructural development, its liberal prescriptive techno‐political models, and the speculative logics of endless ruination. Yet, failures can also become generative, instigating new political imaginaries and historical subjectivities. The article pays special attention to competing modalities of power, focusing on the collective power of oppositional groups, coupled with the material recalcitrant power of local hydrogeology, in resisting unviable, speculative infrastructure.