Harperrig Reservoir

Harperrig Reservoir lies in West Lothian, four miles south of Mid Calder, set in a basin on the northwestern side of the Pentland Hills. The Water of Leith flows through it, fed by nearby Harlaw and Threipmuir reservoirs. Created in 1860 to supply drinking water to Edinburgh, it once guaranteed water for mills along the Water of Leith. The dam was raised in 1890, and in 2006 ownership passed to the City of Edinburgh Council. Modifications in 2007–2008 allowed the reservoir to store flood water and regulate downstream flow. The reservoir holds over four million cubic metres of water across ninety-four hectares. Its dam stands fifteen metres high and spans one hundred and twenty metres. Bronze Age burial mounds lie on East Cairn Hill and West Cairn Hill within the catchment area. The Old Schoolhouse at Causewayend is a listed building, and Cairns Castle, built around 1440 by George Crichton, projects into the water from a hillock. These sites add layers of history to the landscape. Visitors find a peaceful setting for walking and wildlife watching. Eurasian otters use the reservoir, and an artificial holt has been provided for them. Gull Island offers safe breeding grounds for gulls and wildfowl, while geese and ducks winter here. The stonefly leuctra leuctra has been recorded at only four sites in the Lothians, one of which is Harperrig. The Pentland Hills provide a scenic backdrop, making it a place for quiet exploration.