The River Irwell is a 39-mile (63 km) long river which flows through the Irwell Valley in the counties of Lancashire and Greater Manchester in North West England. The river's source is at Irwell Springs on Deerplay Moor, approximately 1.5 miles (2.4 km) north of Bacup, in the parish of Cliviger, Lancashire. The Irwell flows through (and separates) the city centres of Manchester and Salford, before joining the River Mersey near Irlam.
The lower reaches of the river were adapted for use as a trading route during the 17th and 18th centuries, and the stretch between Manchester and the River Mersey became part of the Mersey and Irwell Navigation. Large sections of the river west of Manchester were changed radically during the construction of the Manchester Ship Canal, which opened in 1896, turning Manchester and Salford into a major sea port and leading to the development of Trafford Park, which became the largest industrial estate in Europe. Changes were also made to prevent localised flooding throughout Manchester and Salford, particularly the rerouting of the river via the Anaconda Cut in Salford in 1970 and the River Irwell Flood Defence Scheme, completed in the early years of the 21st century.
