Turlough (lake)

A turlough (turloch or turlach in Irish) is a seasonal or periodic water body found mostly in limestone karst areas of Ireland, west of the River Shannon. The name comes from the Irish tur, meaning "dry", and loch, meaning "lake". The water bodies fill and empty with the changes in the level of the water table, usually being very low or empty during summer and autumn and full in the winter. As groundwater levels drop the water drains away underground through cracks in the karstic limestone. Turloughs are almost unique to Ireland, although there is one example in Wales, Pant-y-Llyn at Cernydd Carmel near Llandeilo. They are of great interest to many scientists: geomorphologists are interested in how turloughs were formed, hydrologists try to explain what makes turloughs flood, botanists study the unusual vegetation which covers the turlough floor, and zoologists study the animals associated with the turloughs. Turloughs are mostly found on the central lowlands west of the Shannon, in counties Galway, Clare, Mayo, and Roscommon, although a few are also found elsewhere, e.g. in Limerick, Sligo, Longford, and Cork. Only three turloughs have been identified in Northern Ireland, namely Roosky, Green, and Fardrum Loughs located near Ely Lodge Forest in County Fermanagh. These constitute the most northerly turloughs in Ireland and have been collectively designated a Ramsar site and an Area of Special Scientific Interest. There is one turlough in South Wales, Pant y Llyn. Rahasane turlough in County Galway is the largest surviving turlough in Ireland and is an important location for migrating and overwintering birds. It is noted for its greater white-fronted geese, whooper swans, wigeon, teal, and many waders in winter. Waterbodies analogous to turloughs can be found elsewhere in the world where similar rainfall patterns, rock type and water table occur. In Eastern Canada (Quebec, New Brunswick and Newfoundland) temporary waterbodies called les lacs mystérieux occur.