 The river rises near Fiendsdale Head in the Forest of Bowland and flows first westwards then southwards through the villages of Oakenclough and Calder Vale before passing under the M6 motorway, West Coast Main Line and under the Calder Aqueduct on Lancaster Canal.It meets the Wyre at Catterall near the town of Garstang, at which point the Calder forms the boundary between the parishes of Catterall and Barnacre-with-Bonds.The Calder is one of two rivers in Lancashire with the same name; the other River Calder flows from Burnley and into the River Ribble.