Silent Valley Reservoir

In 1891, the Belfast Water Commissioners (BWC and later the Belfast City and District Water Commissioners or BC&DWC) hired Luke Livingston Macassey to investigate options for a source of an additional water supply for the expanding city of Belfast. Macassey selected the Mourne Mountains for the reasons summarised in a 1935 report:<blockquote>The portion of the Mourne Mountains acquired by the Commissioners totals approximately 9,000 acres. It is all mountainland [sic], uninhabited, and a large part of it is rocky and precipitous. It extends from about 330 feet above sea-level to a maximum of 2,796 feet above sea-level, Slieve Donard being the highest mountain within the area. It is…

Between 1947 and 1951 over 150 men drove a tunnel underneath Slieve Binnian. The tunnel was built to carry water from the Annalong valley to the Silent Valley Dam, which had been completed in 1933, 14 years earlier. This was to further supply the growing demands of Belfast's water supply. Two work squads began at each end of the tunnel, and met half way almost 800 metres under the mountain. The technology in the day was lacking in every standard, and was lit by candlelight. When the two squads met, they were mere inches off. The tunnel measures 8 ft square – and 2.25 mi long. Its entry is at Dunnywater and its exit is on the roadside, a short distance from the visitor's centre. The Binnian…