Tigris–Euphrates river system border. Since the 1960s and in the 1970s, when Turkey began the GAP project in earnest, water disputes have regularly occurred in addition to the associated dam's effects on the environment. In addition, Syrian and Iranian dam construction has also contributed to political tension within the basin, particularly during drought. The general climate of the region is subtropical, hot and arid. At the northern end of the Persian Gulf is the vast floodplain of the Euphrates, Tigris, and Karun Rivers, featuring huge permanent lakes, marshes, and forest. The aquatic vegetation includes reeds, rushes, and papyrus, which support numerous species. Areas
Chicago River lowest since 1918. In 2012 Lake Michigan-Huron's seasonal rise was about 4 inches where it usually is about 12 inches. Normally the Chicago River water level is two feet lower than the lake and therefore does not flow into the lake. If the lake level falls too low threatening to reverse the river flow, the Metropolitan Water Reclamation District of Greater Chicago would be forced to close locks between the lake and river for longer periods of time limiting navigation. A reversal flow of the Chicago River into Lake Michigan would have a negative impact on navigation and on the