Loughs

A lough is a body of water that is typically described as a lake in Ireland and parts of the British Isles. In Irish and Scottish usage, loughs are common place-name elements and may denote freshwater lakes or seawater inlets connected to the sea. The term is derived from the Gaelic loch, with spellings such as lough reflecting Anglicized forms.

While most loughs are freshwater bodies formed by glacial processes, some are tidal or brackish and function as estuaries or sea inlets. They occur in upland and lowland areas, often in landscapes shaped by glaciation and faulting. They may be isolated basins with no surface outlet or open-basin systems with rivers entering and exiting.

Hydrology and ecology: Loughs vary in size, depth, and water quality. They support diverse aquatic communities, including freshwater fish such as trout and eel, and provide habitat for birds and amphibians. Eutrophication and invasive species pose management challenges in some loughs; many are monitored for water supply, fisheries, and conservation.

Human use and significance: Loughs are central to recreation (fishing, boating), tourism, and local economies. They can be important sources of drinking water and are sometimes linked to hydroelectric power or flood management infrastructure. Notable examples include Lough Neagh, the largest lake by area in the British Isles; Lough Erne, a twin-lake system in County Fermanagh; and Lough Corrib near Galway.