During the Industrial Revolution, Grejs River was used as a source of water power for about 14 watermills, which powered textile, paper, and metal factories [REF].
As of 2016, a pumping station was under construction at the confluence of Vejle River and the Omløbsåen branch of Grejs River in order to prevent high water levels in Vejle River and Vejle Fjord from backing up into Grejs River and causing floods [REF].