The Sydenham River is a river in Chatham-Kent, Lambton County and Middlesex County in southwestern Ontario, Canada, flowing southwest from its source west of London, Ontario and emptying into Lake Saint Clair.
It was named after Lord Sydenham, governor of Canada from 1839 to 1841.
Unusual concretions, composed of calcite, can be found near this river.
[2][3] Because this river flows through a large agricultural area, its waters collect silt and fertilizer runoff.
In spite of this, the river provides habitat for 80 fish species and 34 species of freshwater mussels; these include: The Northern madtom (Noturus stigmosus), once found in the river, is considered to be "likely extirpated".