Coole-Garryland Nature Reserve is located in the glacio-karstic landscape of the Gort lowlands, Co. Galway. It is the centre of a unique wetland system.
Water draining from the bogs of the sandstone Slieve Aughty Mountains to the east makes its way, via a combination of over ground and underground routes, to Coole Lough. It brings with it, silt from the mountains.
At the same time, water draining from the limestone lands of the Burren, to the south, makes its way north towards Coole, via underground channels, and fills Newtown turlough. This water is very unusual in a European context. Despite the fact that it has as its source a limestone area, the water is in fact, poorer in nutrients than the water coming in to Coole Lough from the Slieve Aughty Mountains. At high water levels, Newtown and Coole loughs merge.
The water makes its way from Coole, via an alternating series of turloughs and underground pathways, to eventually reach the sea at Kinvara.
Coole Lough itself is a large turlough and like most turloughs, empties underground through “swallow holes” in its lake bed. It has the largest range in water level fluctuation of any turlough in Ireland. Water levels in the lake can fluctuate by over 10m. The lake generally does not fully empty in summer however and usually retains a small area of permanent water.
A remarkable feature of the turloughs at Coole and Garryland is their close association with woodland. Indeed, large areas of woodland in the nature reserve are covered by water in winter. Plants that live in the turlough must be able to survive both prolonged inundation and drought. Carpets of silverweed (Potentilla anserina) with its silver leaves and yellow flowers may be seen in summer when the water levels have retreated. In certain turloughs, the rare fen violet (Viola persicifolia) may be found. In fact, this plant has its stronghold in Ireland at Coole Lough. Other rare turlough plants found at Coole-Garryland Nature Reserve include shoreweed (Litorella uniflora), and a species of starwort (Callitriche palustris).
Turloughs are classified as Priority habitats under the EU Habitats Directive owing to the rarity of this habitat in a European and world context. The habitat is almost unique to Ireland.
Its location at the centre of a unique and complex karstic aquatic system makes Coole wetland complex a site of Global importance. The extreme level of fluctuation of the lake water level, the unusual close association of the turlough with woodland, the large assemblage of wetland plant communities and the combination of interesting species associated with the lake goes to make Coole Lough the most important turlough in Ireland – and thus in the world.