My dissertation investigates how the formation of new states in the Middle East after World War I affected the exploitation of water resources. Prior to the war, the Ottoman Empire controlled the Tigris-Euphrates river system. When the Allies defeated the Ottomans in 1918, European powers divided the lower basin into French Syria and British Iraq, while the new Turkish Republic’s borders encompassed the upper reaches. My thesis traces a series of changes in the basin’s environment–from floods to massive dams–to demonstrate how different forms of governance shaped the management of a vital resource and the communities sustained by that resource.