Lough Foyle, sometimes Loch Foyle, is the estuary of the River Foyle, situated between County Donegal, Republic of Ireland, and County Londonderry, Northern Ireland.Ramsar siteThe Lough Foyle Ramsar site , is 2204.36 hectares in area, at Latitude 55 05 24 N and Longitude 07 01 37 W. It was designated a Ramsar site on 2 February 1999. The site consists of a large shallow sea lough which includes the estuaries of the rivers Foyle, Faughan and Roe. It contains extensive intertidal areas of mudflats and sandflats, salt marsh and associated brackish ditches. The site qualified under Criterion 1 of the Ramsar Convention because it is a particularly good representative example of a wetland complex which plays a substantial hydrological, biological and ecological system role in the natural functioning of a major river basin located in a trans-border position. It also qualified under Ramsar criterion 2 as it supports an appreciable number of rare, vulnerable or endangered species of plant and animal. A range of notable fish species have been recorded for the Lough Foyle estuary and the lower reaches of some of its tributary rivers. These include Allis shad, Twait shad, smelt and sea lamprey, all of which are Irish Red Data Book species. Important populations of Atlantic salmon migrate through the system to and from their spawning grounds.