Question: What river is Simister near?

Context paragraphs:
Prestwich: Prestwich ( ) is a town within the Metropolitan Borough of Bury, in Greater Manchester, England.  It lies close to the River Irwell, 3.3 mi north of Manchester city centre, 3.1 mi north of Salford and 4.7 mi south of Bury.

Simister: Simister is a small village in Prestwich, within the Metropolitan Borough of Bury, Greater Manchester.  Historically part of Lancashire, it is located between the districts of Prestwich, Rhodes and Langley.  The village is located east of "Simister Island", motorway junction 18 which links the M62, M66 and M60 motorways.  Thousands of vehicles a day use this motorway intersection and the traffic noise is often regarded as a nuisance but not a part of the village by the residents.  Although the village's proximity to Manchester means the residential population is mainly made up of commuters, the village has a rural feel with much agricultural activity.  The main thoroughfare, Simister Lane, is often used as a rat run for cars travelling to and from Prestwich, Middleton and Junction 19 of the M60.

Supporting paragraphs: Simister Prestwich
Answer: River Irwell