Stable political order in Iraq has always hinged on the successful management of the Tigris and Euphrates’ water supplies to meet the demands of states and settlers for irrigation and transportation. This paper focuses on the Ottoman period in Iraq between 1638-1750 and analyzes how Ottoman policymakers in Baghdad and Istanbul worked closely with local kin groups to manage the rivers flowing in the empire’s easternmost frontier to cement the sultan’s political authority over the region’s subjects. The paper argues that Ottoman hydraulic management was a key to cement the sultan’s political authority over the region’s subjects via a condominium system of joint rule between the Ottoman imperial center and provincial society. In some instances, Ottoman authorities even included the Safavid Empire into this arrangement to ensure the successful execution of waterworks in its distant province. In the Ottoman system of shared authority over water, the imperial center placed the management of irrigation largely in the hands of local kin groups without an overall plan and centralized bureaucracy. Kin groups operated as irrigation units, co-operating in digging canals and branches and in building dams to achieve their common goals. Nevertheless, the Ottoman provincial administration in Baghdad, with financial, technical, and military support from Istanbul, periodically undertook enormous water control projects that local communities alone were ill equipped to carry out. These projects had multiple purposes, such as channeling water to the shrine cities of Karbala and Najaf, clearing oversized canals from accumulating silt, and damming and shutting river channels supplying water to rebellious tribes. Ottoman scholars have been interested in financial, political, and social instruments the Ottoman Empire deployed to consolidate its authority in the provinces. Ottoman archival sources reveal episodes of cooperation and political challenge between local kin groups and imperial officials in the Tigris-Euphrates region that allow us to build upon this rich literature and examines the less-explored role of water in tying the fates of the smallest Iraqi villages to Istanbul in ways often overlooked.