Union Locks

The Department's description

Exterior description and setting

The Union Lock complex is aligned north-south on the right (Co Down) bank of the River Lagan, a short distance upstream from Moore’s Bridge on the main Lisburn-Hillsborough road.
It comprises four ‘staircase’ locks, with a wider curvilinear passing basin between the top two locks. Heavy vegetation overgrown precluded a thorough survey of each lock chamber; lock 17 at the south end was completely overgrown and its side walls could not be seen at all.
The side walls of the chambers are a mixture of basalt and sandstone, in both rubble and squared form, and are coped with large squared masonry blocks. The quoins of the sluice emplacements are of finely dressed sandstone blocks. In places, the stonework has been replaced with brickwork which undoubtedly reflects 19th and 20th century repairs. There is a cast-iron bollard half way along lock 14, on its east side. Although all the cills survive, the sluice gates are long removed. At the NW side of the passing basin is a small overspill channel, now disused and covered over for most of its length.
The bed of the former canal can be traced south from lock 17 to the Blaris Road. It has been infilled at one point to facilitate the crossing of a new public footpath. Modern houses have been erected to the west of the lock complex and a new hotel to its east.

Historical information

The Union Locks link the Lagan Navigation with the Lagan Canal. The Navigation makes use of the River Lagan for much of its course (hence the term ‘navigation’ rather than ‘canal’) and the section from Belfast to Lisburn was built between 1756 and 1763 by the ‘Corporation for promoting and carrying on an Inland Navigation in Ireland’. Between 1763 and 1765, the river was made navigable from Union Bridge, Lisburn, to Moore’s Bridge, on the main Lisburn - Hillsborough Road at Sprucefield.
Between 1782 and 1793, the Lagan Canal was constructed under the direction of the English canal engineer Richard Owen by the ‘Company of Undertakers of the Lagan Navigation’ from Sprucefield to Ellis’ Gut at the Lough Neagh end. The completion of the canal enabled barges to ply between Belfast, Newry and Portadown some 50 years before the towns were also linked by railway.

During the early stages of this work, the Union Locks were built to connect the end of the navigable section of river to the start of the canal proper. They comprise four locks, numbered 14 to 17 on the system (measured from the Belfast end) and have an overall rise of 35ft (10.6m). The highest one (lock 17, at the south end) is separated from the others by a small curvilinear passing basin. A lock keeper’s house adjoins just south-east of the topmost lock (HB19/08/005).

The 1833 OS six-inch map and all subsequent editions show the locks and adjoining lock house in their present form.
In 1843, control of the Lagan navigation and canal passed from the Company of Undertakers to the Lagan Navigation Company. Of all the waterway enterprises in the north of Ireland, it was the most commercially successful, particularly on the Belfast-Lisburn section where a number of large mills were served.

The Lisburn – Lough Neagh section of the waterway continued to operate until 1947. The Lagan Navigation Company was dissolved in 1954 and its assets transferred to the Ministry of Commerce. In the same year, the canal and Union Locks were officially abandoned. Four years later, in 1958, the navigation between Belfast and Lisburn was also abandoned.
In the 1960s, the M1 motorway was built along the bed of the former canal between Sprucefield and Moira. In 1963, as part of this scheme, a large drainage pipe was laid from the motorway to the top of the Union Locks. Consequentially, water derived from land drains and natural seepage continues to flow through the locks into the Lagan.

In 1971, the lock complex was acquired by Hillsborough Council from the Ministry of Agriculture (who had taken over from Commerce). With the reorganisation of local government in 1973, it was transferred to Lisburn Borough Council.
In 1989, the Council carried out some landscaping works in order to open up the complex as a public amenity. Further work has recently been completed, including the erection of a new steel footbridge over the Lagan from the towpath on the Co Antrim side of the river.

In 2003, the Union Locks became a Scheduled Monument under article 3 of the Historic Monuments & Archaeological Object (NI) Order 1995.

References - Primary sources:
1. PRONI OS/6/3/14/1. First edition OS six-inch map, Co Down sheet 14 (1833).

References – Secondary sources:
1. Green, E.R.R. The Industrial Archaeology of Co Down, pp 70-75 (Belfast: HMSO, 1963).
2. McCutcheon, W.A. The Canals of the North of Ireland, pp 40-61 (Newton Abbot: David & Charles, 1965).
3. Delany, R. Ireland’s Inland Waterways (Belfast: Appletree Press, 1986).
4. McCutcheon, W.A. The Industrial Archaeology of Northern Ireland (Belfast: HMSO, 1980).
5. Blair, M. Once Upon the Lagan (Belfast: Blackstaff Press, 1981).

Criteria for listing: architectural interest

Not listed

Criteria for listing: historic interest

Not listed

Evaluation

The Union Locks comprise a staircase arrangement of four locks connecting the former Lagan Navigation and Lagan Canal. They were built in the early 1780s under the direction of the canal engineer Richard Ower by the ‘Company of Undertakers of the Lagan Navigation’. They survive unaltered save for the absence of their gates. The complex is of architectural interest in terms of the locks' staircase arrangement and because of its group value with the adjoining lock house. They are also of historical interest at a national level as a key part of Ulster’s pre-railway navigable waterways network. They also have considerable rarity value in being the only 4-lock canal staircase in the whole of Ireland. The complex was scheduled in 2003 and it is considered that this is a more appropriate type of protecting that listing.