Millrace near to watch tower, Roe Valley Country Park, Largy, Limavady, Co Londonderry

The Millrace is a significant example of water-powered industrial infrastructure located within Roe Valley Country Park, near Limavady, County Londonderry. Likely dating from the 1760s, when Lesley Alexander of Newtown Limavady established a bleach green at Largy, the mill race originally supplied power for industrial processes along the River Roe, and later served as a source of power for the Dogleap Power Station.

The mill race begins at Given’s Weir, near the site of the former Carrick Corn Mill, running alongside the River Roe towards the field that was once the 'Roe' bleach green. A bywash, crossed by a segmental stone footbridge, returns a portion of the water to the river. Sections of the race have been infilled. One branch formerly served the Wash Mill, while the continuation past the watch tower and towards the mill pond at the Roe Valley Reception Centre is now filled. The weir itself is constructed of concrete, featuring a central fin that diverts water to the opposite bank, protecting a nearby river wall and sluice gate. The sluice gate’s timber construction is similar to that at O’Cahan’s Rock, with a concrete footway supported on rail tracks. Although the metal machinery and gates have been removed, the sluice retains timber boards nailed to the front, limiting water flow. A date of 1931 is inscribed on the concrete construction on the river side of the sluice, built likely over an earlier stone foundation. The mill race’s sides remain visible despite its rapid loss of water, and the race splits into two parallel channels, rejoining at intervals before ending abruptly. A modern timber footbridge runs parallel to the original stone arch footbridge over the bywash.

The system of mill races was renovated and expanded in the late 19th century to meet the increased water demands of the Dogleap electricity station, including the addition of the two parallel races intended to maintain water supply to Dogleap Farm. The races were maintained by the Limavady Electricity Supply Company and subsequently the Northern Ireland Electricity Board until the station's closure in 1967. The mill race is now part of the Roe Valley Country Park, established in 1976. Outside of the park, the section of race was infilled in the 1980s to improve farming efficiency on the former bleach green. The Millrace is considered to be derelict and of industrial archaeological interest.