The River Irwell is a long river which flows through the Irwell Valley in the counties of Lancashire and Greater Manchester in North West England. The start of the river is at Irwell Springs on Deerplay Moor, about north of the town of Bacup, in the parish of Cliviger, Lancashire. The Irwell flows through the city centres of Manchester and Salford, before joining the River Mersey near Irlam.