The Sleaford Navigation was a 12.5-mile (20.1 km) canalisation of the River Slea in Lincolnshire, England, which opened in 1794. It ran from a junction with the River Witham, near Chapel Hill to the town of Sleaford through seven locks, most of which were adjacent to mills. Lack of finance meant that it stopped short of its intended terminus, but it gradually grew to be successful financially. The coming of the railways in 1857 led to a rapid decline, and it was officially abandoned by an act of Parliament in 1878, but remained open for a further three years. The lower part of it remained navigable until the 1940s, when it was blocked by a sluice.

The River Witham is a river almost entirely in the county of Lincolnshire in the east of England. It rises south of Grantham close to South Witham at SK8818, passes through the centre of Grantham, passes Lincoln at SK9771 and at Boston, TF3244, flows into The Haven, a tidal arm of The Wash, near RSPB Frampton Marsh. The name "Witham" seems to be extremely old and of unknown origin. Archaeological and documentary evidence shows the importance of the Witham as a navigable river from the Iron Age onwards. From Roman times it was navigable to Lincoln, from where the Fossdyke was constructed to link it to the River Trent. The mouth of the river moved in 1014 following severe flooding, and Boston became important as a port.