 The river is formed by the confluence of Peasey Beck and Stainton Beck at Overthwaite.It runs through Beetham where it still powers the Heron Corn Mill, and formerly powered the Billerud paper mill.It then flows through the deer park of Dallam Tower before skirting around the south of the village of Milnthorpe and joining the River Kent estuary between Sandside and Milnthorpe.