Mourneside Walk, Liskey Road, Liggartown, Sion Mills

Set of iron and timber sluice gates erected around 1890 on the west bank of the Mourne river at Sion Mills, just north of a stone weir. Reputedly one of the widest sets of sluice gates in Ireland, these gates represent a significant example of late Victorian hydro-engineering and a reminder of the industrial past of Sion Mills.

The north sluice spans the mill race by approximately 10 metres, with a further sluice to the east allowing the mill race to flow into the Mourne river, spanning approximately 4 metres. Each sluice is constructed of large vertical timber beams with cast-iron cappings, and horizontal timbers forming a gate between the vertical beams. A horizontal beam is supported by a series of timber console brackets which supports the cast-iron rack and pinion gears. The smaller sluice to the east has a cast-iron frame with a pair of S-shaped cast-iron brackets laid into the river bed. Both gates now have walkways, with steel grid to the east gate and bitumac to the north gate. Rubblestone walling flanks the east gate.

The sluice is first captioned on the third edition Ordnance Survey map of 1906 across the mill race leading to the flax spinning mills at Sion Mills. The second edition map of 1855 captions a flood gate on the same site, though the present sluice gate has iron elements of late 19th or early 20th century appearance.

Sluice gates of this type were used to control the flow of water onto water-wheels. Placed near or at the junction of the main inlet with a weir, they allowed careful control of water entry into the head race, particularly during winter months when floods posed a hazard. The gates could also be used to drain the mill-race for maintenance and repairs. The width of the head race channel varied according to the power requirements of the mill unit, with wider channels required for greater power input. The sluice gates themselves generally consisted of a stout wooden framework with a large sill beam across the channel bed, into which a series of vertically grooved timber beams were morticed. Vertical gate sections made up of horizontal boards were slotted between these uprights and raised or closed by cast-iron rack and pinion gears, manually operated with a simple crank.

The structure is recorded for heritage purposes but is not the type of structure protected through listing on its own.