Lough Neagh water level maintenance

Numerous rivers  flow into Lough Neagh which in turn discharges to the sea via the Lower Bann River. The Lough Neagh catchment drains 43% of the land area of Northern Ireland, as well as some border areas in the Republic of Ireland.

The Agency is required to regulate and control water levels in Lough Neagh within a specified range, that is 12.45 metres to 12.6 metres Ordnance Datum, as defined in the Lough Neagh Levels Scheme (1955) (as amended).

Water levels in the lough are controlled by means of 3 sets of flood gates situated on the Lower Bann River. These are located at Toome, Portna (near Kilrea), and The Cutts at Coleraine. Incremental adjustment of floodgates is practiced, whenever possible, in order to minimise impact on the range of environmental and other interests associated with the lough.

The channel in the Lower Bann River, downstream of Lough Neagh, tends to impede the rate of outflow from the lough during periods of heavy rainfall. At such times the floodgates at Toome are fully opened, where possible, in advance of an anticipated rise in water level.