The River Irwell is a 39-mile (63 km) tributary of the River Mersey in north-west England, rising at Irwell Springs on Deerplay Moor approximately 1.5 miles north of Bacup. From its moorland headwaters, the river flows southward through Rawtenstall, Ramsbottom, and Bury before passing through the urban landscapes of Manchester and Salford, where its lower reaches have been canalised as part of the Manchester Ship Canal. The Irwell marks the historic boundary between Manchester and Salford and represents one of the great environmental recovery stories in English angling history. Once devastated by industrial pollution during the Industrial Revolution, the river has undergone remarkable rehabilitation through decades of water quality improvement initiatives, restocking programs, and habitat enhancement efforts. Today, the Irwell supports a genuine mixed fishery capable of producing trout, grayling, and coarse species across its varied reaches.