Before granting export credits to the companies that want to build the Ilisu Dam on the Tigris river in Southeast Turkey, the governments of several European countries and the USA required a full consideration of the environmental consequences of constructing and operating the dam. This review examines the environmental impact assessment’s analysis of the dam’s downstream impacts, and concludes that, if built, the Ilisu dam could cause major disruptions to water flow to Syria and Iraq, the two countries that share the Tigris with Turkey.