The Herk is a small river in Limburg Haspengouw. The watercourse rises in Rukkelingen-Loon (municipality of Heers) near the provincial border of Limburg - Liège. It is additionally fed at Sint-Lambrechts-Herk by the inflowing Mombeek. At the border between Herk-de-Stad and Halen it flows into the Gete.
Thanks to the water purification plant in Alken (1998), the water quality is good, which was different in the past, when the Alken brewery used the water from the Herk for cooling and the river also served as a drainage channel.
The river gives its name to several places it passes, such as Herk-de-Stad and Sint-Lambrechts-Herk. Many castles have been built in the valley of the Herk, including the castle of Rullingen. The towns of Wellen, Alken, Voort, Gotem, Hoepertingen, Berlingen, Herten, Terkoest and Stevoort and a number of watermills are also located on the Herk. The name Herk comes from the Celtic word arika, diminutive of ara which means river. So Herk means small river or stream.