Watershed Moments highlights changes in democratic governance and environmental policy in twentieth-century America by exploring the development and elaboration of New York City's water supply network. Unlike most historical treatments of municipal water supply, this study emphasizes water management over system construction. Placing issues of management at the center of the narrative reveals the transformations in City water policy and the growing trend toward resource cooperation that marked the final decades of the twentieth century. Sociologists and political scientists have recognized the increasing tendency toward consensus on thorny environmental conflicts in the 1990s, but they have not probed the historical forces behind this transformation. This study fills this important gap in the literature though a careful analysis of the country's most extensive water supply network.