Silent Valley Reservoir

The Silent Valley Reservoir lies in the Mourne Mountains near Kilkeel in County Down. It is a large water storage lake built between 1923 and 1933 by more than a thousand workers. Nine men lost their lives during its construction. The reservoir supplies most of County Down and much of Belfast with drinking water. It was the second stage of a plan first investigated in 1891 by Luke Livingston Macassey on behalf of the Belfast Water Commissioners. Macassey chose the Mourne Mountains because of their high rainfall and excellent water quality. The reservoir sits in a valley once called Glen Setanta after the legendary Cú Chulainn. Later it was known as Happy Valley because of Cornish miners who worked there. The name Silent Valley comes from the lack of birds during the long construction period. The dam was built across the Kilkeel River after delays caused by the First World War. A second dam at Ben Crom was added later to increase storage. The Mourne Wall surrounds the catchment area and was built entirely by hand over eighteen years. Visitors reach the reservoir along a roadside visitor’s centre near Dunnywater. The Binnian Tunnel, driven between 1947 and 1951, brings water from the Annalong valley through Slieve Binnian. The tunnel is 3.62 kilometres long and was dug by two teams working from opposite ends. They met almost 800 metres underground with only inches to spare. The tunnel’s square entrance and exit are clearly marked beside the road. From the visitor’s point, paths lead into the surrounding mountains where heather and gorse cover the rocky slopes.