The River Witham is a river, almost entirely in Lincolnshire, in the east of England. It rises south of Grantham close to South Witham, at SK8818, passes Lincoln at SK9771 and at Boston, TF3244, flows into The Haven, a tidal arm of The Wash.

Tributaries of the River Witham:

• Foston Beck
• River Brant
• Fossdyke Navigation, a canalization of the lower River Till.
• Barlings Eau
• River Bain
• Kyme Eau, the fenland part of the River Slea

• South Forty-foot drain
• Maud Foster Drain
• Hobhole Drain

See also

• Rivers of the United Kingdom

Rivers in Lincolnshire