The River Chor is a largely culvert

Culvert

A culvert is a device used to channel water. It may be used to allow water to pass underneath a road, railway, or embankment. Culverts can be made of many different materials; steel, polyvinyl chloride and concrete are the most common...

ed stream

Stream

A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

 in the Lancashire

Lancashire

Lancashire is a non-metropolitan county of historic origin in the North West of England. It takes its name from the city of Lancaster, and is sometimes known as the County of Lancaster. Although Lancaster is still considered to be the county town, Lancashire County Council is based in Preston...

 town of Chorley

Chorley

Chorley is a market town in Lancashire, in North West England. It is the largest settlement in the Borough of Chorley. The town's wealth came principally from the cotton industry...

. Its name was back-formed

Back-formation

In etymology, back-formation is the process of creating a new lexeme, usually by removing actual or supposed affixes. The resulting neologism is called a back-formation, a term coined by James Murray in 1889...

 from "Chorley".

The source of the river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 is in the hills near Heapey

Heapey

Heapey is a village and civil parish of the Borough of Chorley, in Lancashire, England. The village is two miles from Chorley and on the western fringe of the West Pennine Moors. In 2001 the population was 955.- History:...

.

Subsequently, the young stream flows through Chorley North Industrial Estate, past B&Q

B&Q

B&Q plc is a multinational DIY and home improvement retailer headquartered in Eastleigh, United Kingdom. It was founded in 1969 and is a wholly owned subsidiary of Kingfisher plc, which is listed on the London Stock Exchange....

 and then underground to Astley Park.

The river exits at the Southport Road end of the park, flowing behind Chorley Nissan and through Big Wood at the foot of Stansted Road, before connecting into Gillibrand Reservoir.

At the end of the reservoir, the river continues for several hundred metres and flows into the River Yarrow

River Yarrow (Lancashire)

The River Yarrow is in Lancashire, with its source at an area called Will Narr at Hordern Stoops, along Spitlers Edge - the Chorley/Blackburn boundary - on the West Pennine Moors. The river feeds the Yarrow Reservoir, which in turn feeds the Anglezarke and Upper and Lower Rivington Reservoirs...

.