The Sydenham River is a river in Grey County in southern Ontario. The river flows north from a source near Williamsford, drops over the Niagara Escarpment at Inglis Falls and empties into Owen Sound harbour on Georgian Bay. The Spey River is a tributary of this river. There is also a larger Sydenham River in Kent County, Ontario which empties into Lake Saint Clair. Both rivers were named after Lord Sydenham, governor of Canada from 1839 to 1841.
