When coal was discovered in Co Tyrone in the 1690s, the idea of creating a navigable link with Belfast became attractive. The building of the Newry Canal in the 1730s, to whisk that coal by sea to Dublin, added a new urgency to the situation if Belfast was to develop as a competing port.
Work commenced in 1756 under the direction of Thomas Omer. In September 1763, amid scenes of great enthusiasm, the first boat made the passage from Belfast to Lisburn. Work continued to Sprucefield during the following four years, but by 1768 had stopped completely because of lack of funding.
In 1779 a private company was formed in which the Marquis of Donegall held a controlling interest. An English engineer, Richard Owen, was employed to oversee the works and the navigation was carried up through four locks (the Union locks) to a summit level that extended for four miles to Aghalee. From here the canal dropped approximately 70ft over a distance of 3.2 miles through ten locks, each 70ft X 16ft, and in December 1793 the route was driven through to the shore of Lough Neagh at Ellis's Gut.
In 1810 control of the company passed to a group of Belfast businessmen and merchants. Improvements were made and traffic increased, particularly between Belfast and Lisburn. In 1842 legislation was passed creating a new private Lagan Navigation Company.
Steady improvement in trade continued, competing successfully with both the Ulster Railway and the new roads of the Lagan valley. During the latter part of the 19th century the Lagan Navigation flourished, transporting coal, grain and
general merchandise upstream from Belfast with sand, native timber, fireclay goods and bricks being the main cargoes to Belfast.
By the mid-1930s competition from road and rail brought a decline in
tonnage and revenue. Despite government subsidies, the post-war years saw only negligible traffic and in 1958, after the Lagan Navigation Company had been
dissolved by the Inland Navigation Act (NI) 1954, the route was officially abandoned.