The River Ancholme is a river in Lincolnshire, England, and a tributary of the Humber. It rises at Ancholme Head, a spring just north of the village of Ingham and immediately west of the Roman Road, Ermine Street. It flows east and then north to Bishopbridge west of Market Rasen, where it is joined by the Rase. North of there it flows through the market town of Brigg before draining into the Humber at South Ferriby. It drains a large part of northern Lincolnshire between the Trent and the North Sea.
The river has been used by humans since at least 800Â BC, seen by the excavation of a planked boat at Brigg. Letters patent for improvements to the river are known from 1287 onwards. Major change occurred in 1635, when a new straight channel was constructed from Bishopbridge to Ferriby. The new channel carries most of the water, the New River Ancholme, whereas the Old River Ancholme still meanders. The latter is mostly reduced to a ditch, save around Brigg's central 'Island Carr'. Further improvements were started by John Rennie (the Elder) in the early 1800s and completed by his son in the 1820s, with the reconstruction of Ferriby Sluice taking place around 1841.