Colonial difference is a story of national infrastructures. To understand how colonialism works across Indigenous lands, we need to appreciate the physical, legal, and political factors involved in the building and expanding of national infrastructures in different historical contexts; infrastructures that arrive in some places while denied in others. Using archival documents, this article accounts for the colonial politics necessary to bring Colorado River water into Phoenix and Tucson. It highlights how the following moments worked to enlarge Arizona’s population and power while denying Diné water claims: the 1922 Colorado Compact, Arizona’s 1960s campaign for the Central Arizona Project, and recent Indian water settlements between Arizona and Navajo Nation. The infrastructures that emerged from these events formed a coal–energy–water nexus reliant on Navajo coal while constructing Arizona’s water network. In sum, these projects served as colonial beachheads—temporal encroachments on Indigenous lands and livelihoods that augment material and political difference over time and exacerbate inequalities.