[3] In 1891, the commissioners appointed local civil engineer, Luke Livingston Macassey to identify water resources to sustain Belfast.

c. xcv), allowed the purchase of the Mournes land and related access permits and water rights.

[4] At the time the catchment was capable of providing some 30 million imperial gallons (140,000 m3) of water per day, however because this was more than was required at that point, a three phase scheme was developed.

The first stage was to divert water from the Kilkeel and Annalong rivers through the Mourne Conduit to a reservoir near Carryduff.

The BC&DWC made representations to that body, objecting to any movement of the border north from the existing County Down boundary on the following grounds:[13] The border was ultimately unchanged, leaving the Mourne catchment area and water infrastructure within Northern Ireland.

The powers vested in the Belfast City and District Water Commissioners were transferred to the Minister of Development on 1 October 1973.