The River Croal is a river located in Greater Manchester, England. It is a tributary of the River Irwell. Rising at the confluence of Middle Brook and Deane Church Brook, it flows eastwards through Bolton, collecting Gilnow Brook and the larger River Tonge at Darcy Lever. Most of the river is culverted through Bolton town centre, running under Knowsley Street; Market Place and Bridge Street.Before 1836 the River Croal formed the boundary between the townships of Great and Little Bolton. It meets the Irwell at Nob End, Kearsley after a total course of around ten miles.