Silent Valley Reservoir

The Mourne Wall (Irish: Balla an Mhúrn) was constructed to enclose a catchment area of the Silent Valley Reservoir in the Mourne Mountains, Northern Ireland. The 1.5 metres (4 ft 11 in) high stone wall, which was built to keep livestock from contaminating water supplies, took almost twenty years to complete (1904 to 1922).

The Silent Valley Reservoir is a reservoir located in the Mourne Mountains near Kilkeel, County Down in Northern Ireland. It supplies most of the water for County Down, surrounding counties and most of Belfast. It is owned and maintained by Northern Ireland Water Limited (formerly DRD Water Service).

The Binnian Tunnel (2.5 miles long) was constructed between 1947 and 1950/51 and is located under the Mourne Mountains in County Down, Northern Ireland. The main purpose of the tunnel is to divert water from the Annalong Valley to the Silent Valley Reservoir underneath Slieve Binnian, after which the tunnel was named.