Millrace and Sluice Gate, O’Cahans Rock, Roe Valley County Park, Limavady, Co Londonderry, BT49 9EY

This is a piece of industrial archaeology associated with the history and development of Limavady. While the overall infrastructure may be very old, the individual components largely date to the late 19th and early 20th centuries. It is traditionally believed to be the millrace built by Sir Thomas Philips in 1611 to serve his mill at Roemills, although some believe the race dates back to the 13th century, serving a Norman mill, with Philips simply repairing the existing structure.

The sluice gate is situated in a picturesque location on the River Roe, near the base of O’Cahan’s Rock. It consists of six vertical timbers with cast iron saw teeth, suspended from two horizontal timbers with a cast iron gearing system including a centrally placed 300mm cog. A stone retaining wall, 800mm wide with two small parapets along a path, surrounds the gate. A low-level concrete bridge, set between two railway tracks, spans the river opening. A weir in the river, largely intact, serves the sluice. The millrace is approximately 2½ metres wide and has stone walls on either side in places.

A second entrance to the millrace, more perpendicular to the river and served by a more decayed weir known as the ‘Old Weir’ or ‘Philips Weir’, is located nearby, crossed by a small timber bridge. Further along the race, two small, picturesque stone bridges are present, one with a segmental arch and no parapets, and the other with a semi-circular arch and recent repairs. These bridges lead to the end of the race near Roemill. The present appearance of the weir, sluice, and race is largely the result of renovations carried out in 1926, when the Limavady Electric Supply Company purchased Roemills to generate hydroelectricity.