This paper examines elite families’ use of the institution of waqf to consolidate control over irrigation infrastructure in the northern Egyptian Delta in the late-eighteenth century. I argue that this process underpinned the thorny relationship between the Ottoman state and Egypt’s Mamluk households during the critical period from 1760-1810. Shari’a court records from Egypt demonstrate that Janissary and Mamluk officials in the coastal Delta cities of Rashid (Rosetta) and Dimyat (Damietta) established charitable and family waqfs that gave them alienable and heritable rights to agricultural land and the vital system of wells, water-wheels, and ditches necessary for intensive cultivation. Meanwhile, statesmen in Istanbul remained actively invested in maintaining imperial access to the produce of irrigated agriculture in Egypt through the turn of the nineteenth-century, despite repeated threats from war, natural disasters, and political challenges on the ground. This paper offers a ground-level view of one such challenge to Ottoman sovereignty in Egypt: the legal institution of waqf constituted an important mechanism by which provincial elites within the Ottoman system rooted their power in Egyptian soil. While most lands in the Egyptian Delta were governed remotely as tax-farms, the irrigated urban hinterlands of Rashid and Dimyat were within reach of the Janissary- and Mamluk-affiliated families who controlled them via waqf. Scholars are increasingly drawn to the study of waqf as a means to explore family history, urban development, and the legal establishment of private property in Ottoman history. By highlighting the role of waqf in governing ownership of and access to irrigation infrastructure, this paper contributes to a growing literature on the rise of new legal and administrative categories of property that restructured state-society relations in the Ottoman Empire. At the same time, such attention to waqf, an institution pervasive throughout the Ottoman lands and governed under the auspices of Ottoman law, challenges the common notion that the case of late-eighteenth-century Egypt falls outside the scope of Ottoman history. This study combines the Shari’a court records from Rashid and Dimyat with an imperial view offered by provisioning records and official correspondence from the Ottoman center in Istanbul. These sources together offer an alternative perspective on the critical decades from 1760-1810, a turbulent time in Ottoman Egypt that is usually reduced to the study of high politics in Cairo.