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: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 practically devoid of trees, being covered with heather, gorse, and bracken where not granite rock and boulders. The average rainfall on the area is 57.6 inches per annum. It is drained by two streams : on the west, the
Kilkeel river flowing due south, and the
Annalong river, lying parallel to and to the east of the Kilkeel river, draining the
Annalong Valley. The catchment of the Kilkeel river is 5,500 acres in extent, that of the Annalong river being 3,500 acres. The water of both these rivers is similar and of excellent quality, having 2 degrees of
hardness. Private acts of Parliament – the
Belfast Water Act 1893, the
Belfast Water Act 1897 and the
Belfast Water Act 1899 – allowed the BC&DWC to secure the catchment area with associated access and water rights. At the time the catchment was capable of providing some of water per day, however as this much was not required immediately, a three phase approach was followed: • The first stage was to divert water from the Kilkeel and Annalong rivers through the newly constructed
Mourne Conduit to a reservoir at
Carryduff. These water pipes were capable of supplying of water per day. Work was completed in 1901. • The third stage was planned to be another storage reservoir in
Annalong to impound the Annalong River. However, after the difficulties encountered in building the Silent Valley dam the second dam was not built. Instead, a tunnel was driven under Slieve Binnian between 1947 and 1951 to bring water from the Annalong river to the Silent Valley reservoir. Between 1953 and 1957, a second dam was built further up the Kilkeel river valley to create
Ben Crom Reservoir. The Mournes catchment area is surrounded by the
Mourne Wall, built entirely by hand. Started in 1904, it took 18 years to complete. ==The Binnian Tunnel==