This paper examines Ottoman efforts to develop water supplies in the Tigris-Euphrates basin in the early 20th century, roughly 1903-1914. The Ottoman government hired British irrigation engineer William Willcocks (the engineer who supervised the construction of the first Aswan dam) in 1903 to undertake a survey of the two rivers and create a plan for flood control and irrigation. After 1908, the Committee of Union and Progress invited Willcocks to expand on that initial survey and prepare drawings for a barrage on the Euphrates. This barrage, the Hindiyya, was completed just before the First World War. Though Willcocks’ plan called for several other dams, flood escapes and irrigation works, the Hindiyya barrage was the only part of Willcocks' survey that came to fruition during his lifetime. Still, the Ottoman vision for Mesopotamia, expressed through Willcocks’ designs, became a template for all future development of the two rivers. By investigating Ottoman sources regarding Willcocks’ surveys, this paper analyzes Ottoman ideas of Mesopotamian nature. I use the concept of the “environmental imaginary,” which thus far has been used most profitably to evaluate British and French imperial practices in the Middle East, to understand how the Ottoman government adopted environmental management as a means to integrate Mesopotamia more effectively, and more profitably, into the empire. Furthermore, I argue that this vision of a Mesopotamia integrated through water management survived the disaster of the First World War. I assert that the British invasion and occupation of Iraq should in fact be seen as an interruption in the economic development of the country, rather than its beginning. The Ottoman idea of consolidating political power through environmental management instead survived in an Iraqi government dominated by former Ottoman elites and eventually found expression after Iraqi gained financial independence after the Second World War.