Lakes in the park range from the small lochans to the long deep waters of Lough Veagh, the main body of water in the park. The areas from which the lakes collect their water all lie entirely within the park boundary, making it possible to prevent their pollution.
The waters are clean and well oxygenated and are particularly suitable for a range of species to thrive.
Most of the park’s lakes hold brown trout, salmonoid fish and eels. Lough Veagh has modest runs of salmon and sea trout as well as stocks of arctic charr. Like the salmon the charr is seagoing in arctic and sub-arctic regions, but in western Europe it is confined to freshwater lakes where it has remained since the ice age. The ‘land-locked’ charr require cold and unpolluted water and, with such a commodity now scarce in Western Europe, it has become seriously endangered. Charr populations isolated in different lakes over the past 10, 000 years have evolved slight differences. Recent findings suggest that Glenveagh charr are significantly smaller than those in nearby Dunlewy Lake.
The Glaskeelan river, whose headwaters rise from Lough Inshagh, is an important breeding habitat for the Freshwater Pearl Mussel. These pearl mussels, which are only found in high-quality, near-pristine freshwater habitats, are extremely long lived and are capable of surviving for up to 140 years, making them Ireland’s longest living animal.
Waterfowl are of major interest in Glenveagh and highlight the northern or Scottish connection. Visitors include the red-throated diver, which is increasing in numbers in Scotland and spreading southwards. Lough Veagh has long been the haunt of the red throated diver and it nests in small numbers in the Park’s vicinity, its only Irish breeding centre. The divers feed in nearby coastal waters, and divers calling as they fly in from the sea to their nesting areas are an evocative feature of summer mornings in Glenveagh.