The Ems (German: Ems; Dutch: Eems) is a river in northwestern Germany. It runs through the states of North Rhine-Westphalia and Lower Saxony, and discharges into the Dollart Bay which is part of the Wadden Sea. Its total length is 371 kilometres (231 mi). The state border between the Lower Saxon area of East Friesland (Germany) and the province of Groningen (Netherlands), whose exact course is the subject of a border dispute between Germany and the Netherlands, runs through the Ems estuary.