Glen Lough is situated approximately 5 km north-west of Lough Iron, and is connected to it via the Black River. Both lakes are located in County Westmeath and have suffered drastic drops in water-level subsequent to drainage in the 1960s. As a result both lakes are now occupied by freshwater marsh, with little surface water except when winter flooding occurs. Parts of both lakes have also suffered from the planting of conifers and both are surrounded by farmland. Reedbed fringes, and is encroaching further into, Lough Iron, while Glen Lough supports Salix scrub, reed-swamp, dry grassland, cutaway bog and fen. Wildfowling occurs at both sites.
In recent years numbers of wintering swans Cygnus and Anser albifrons flavirostris have declined at Glen Lough. Birds of the latter species also use Lough Ennell (site 140), Lough Owel (site 139), Lough Derravaragh (site 138) and Garriskil bog (site 136). Dabbling duck occur in large numbers and this is one of the most important sites in Ireland for wintering Anas clypeata (159 birds, 1996). Other species occurring in numbers of national importance are Anas penelope (3,118 birds, 1995), Anas crecca (950 birds, 1995), Aythya fuligula (350 birds, 1995), Fulica atra (370 birds, 1996), Pluvialis apricaria (5,300 birds, 1996) and Vanellus vanellus (7,000 birds, 1995).
Pressure/threats to key biodiversity
In 1997 the Office of Public Works completed maintenance drainage at Glen Lough which resulted in less frequent winter flooding over shorter periods. A complaint in relation to this damage was made to the European Commission. Restoration measures are now in place, though their success is yet to be determined. Also within Glen Lough the area where Anser albifrons flavirostris used to feed has been planted with conifers. At both lakes disturbance to birds is likely due to wildfowling.
National Partial International High182 ha of IBA covered by Wildfowl Sanctuary (Lough Iron, 182 ha). 263 ha of IBA covered by Ramsar Site (Lough Iron-Glen Lough, 263 ha). 81 ha of IBA covered by Special Protection Area (Glen Lough, 81 ha). 82 ha of IBA covered by Special Protection Area (Lough Iron, 182 ha).