永定河
The Hai River forms within Tianjin Municipality at the confluence of the Ziya River (), Daqing River (), Yongding River, North Grand Canal, and South Grand Canal, and enters the Pacific Ocean within the municipality, as well in Tanggu District. Major reservoirs include the Beidagang Reservoir in the extreme south (in Dagang District) and the Yuqiao Reservoir in the extreme north in Ji County.