The ECN Data Centre

Site Information: Lough Neagh

Sponsoring organisation(s)

Agri-Food and Biosciences Institute

Network(s) this site belongs to
UK Environmental Change Network

Site characteristics

Altitude m

The catchment area is indicated with a black line.
Click map to enlarge.

Area of Lake ha
Mean annual pH* 8.3
Mean annual water temperature*
* calculated from the ECN Data Centre database
Information held about this site
View a list of datasets collected at this site
View a list of publications about this site


Lough Neagh covers 386 km2 and is by far the largest area of freshwater in the British Isles. Situated in north-east Ireland, it has a drainage basin of 4450 km2, which is shared between Northern Ireland (91%) and the Republic of Ireland (9%). The average water retention time is 15 months. Although large in area, the lake is relatively shallow with a mean depth of 8.9m (max. 25 m). This, combined with its great size and a mild and windy oceanic climate, ensures that the water column is generally well mixed. The lake supports commercial fisheries for eels, pollan (Coregonus autumnalis pollan Thompson), perch and trout of which the eel fishery is the most significant, with an annual catch in the region of 600 t. Lough Neagh is hypertrophic with a mean annual total phosphorus concentration of 160 mg P l-1. Attempts to lower P concentrations in the lough by curtailing point sources of P have been unsuccessful due to increasing inputs from diffuse sources. Levels of P in the lough support large phytoplankton populations with annual chlorophyll a concentrations typically in excess of 60 mg l-1. The dominant alga is the cyanophyte Planktothrix agardhii (Komarek) Anagnostides and the phytoplankton is now less diverse than in the late 1960s when regular monitoring began. Since then there has been regular monitoring of the plankton, lake and river nutrient concentrations, which have been used to produce nutrient budgets for the lake.

Agri-Food and Biosciences Institute


Related links



Yvonne McElarney

Agri-Food and Biosciences Institute
Newforge Lane, Belfast, BT9 5PX

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