The Leie (Dutch) or Lys (French) is a river in France and Belgium, and a left tributary of the Scheldt. Its source is in Pas-de-Calais, France, and it flows into the river Scheldt in Ghent, Belgium. Its total length is 202 kilometres (126 mi). It is a very polluted river due to the high density of population and industry in the North of France and in Belgium. Historically, the Lys valley was known for the spinning and weaving of flax. The region of the Leie (between Deinze and Ghent) used to be known as a favourite place for numerous painters in the first half of the twentieth century.
The source of the Lys is in the village Lisbourg, east of Fruges, in the Pas-de-Calais department of France. It flows generally northeast through the following departments of France, provinces of Belgium and towns: