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.