Question: Coppull is a village and civil parish in Lancashire, England, it is bounded by which river, 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?
Context: Spitlers Edge is a ridge running along the eastern edge of Anglezarke Moor, Chorley, Lancashire, England from Standing Stones Hill to Hordern Stoops.  The peak, complete with cairn, at 392m, is the high point of the moorland. Rivington is a small village and civil parish of the Borough of Chorley, Lancashire, England, occupying 2538 acre .  It is about 6 mi southeast of Chorley and about 8.5 mi northwest of Bolton.  Rivington is situated on the fringe of the West Pennine Moors, at the foot of Rivington Pike.  According to the United Kingdom Census 2001 it had a population of 144, reducing to 109 at the 2011 Census. Coppull is a village and civil parish in Lancashire, England.  It is part of the Borough of Chorley, lies around 300 ft above sea level.  Its population is around 8,000, having been counted at 7,959 in the 2011 Census.  It is bounded by Whittle Brook, Clancutt Brook, the River Yarrow, Eller Brook, Hic-Bibi Brook and Stars Brook.  Coppull is located between Chorley and Standish, Greater Manchester, to the east of the A49 road near Charnock Richard.  Coppull has been represented on Chorley Borough Council since 2011 by Cllrs Matthew Crow and Robert Finnamore and one other Councillor. Anglezarke is a sparsely populated civil parish in the Borough of Chorley in Lancashire, England.  It is dominated by reservoirs that were built to supply water to Liverpool, and a large expanse of moorland with evidence of Bronze Age settlements.  Popular with walkers and tourists, it lies in the West Pennine Moors in Lancashire, sandwiched between the moors of Withnell and Rivington, and is close to the towns of Chorley, Horwich and Darwen.  At the 2001 census it had a population of 23.  At the 2011 Census the population is included within Heapey civil parish. 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, increasing to 1,001 at the 2011 census. 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. Upon leaving the reservoirs via a pumping station, the river passes through an area that was formerly known as "Abyssinia".  Currently, this area is within the boundaries of Heath Charnock and Limbrick, but the original name was given because it was a route frequented by coal miners, and the workers were said to look like natives of Abyssinia (modern day Ethiopia): until the mid 20th century it was usual for miners to return from work covered in coal dust. Horwich is a town and civil parish in the Metropolitan Borough of Bolton, Greater Manchester, England.  Historically in Lancashire, it is 5.3 mi southeast of Chorley, 5.8 mi northwest of Bolton and 20 mi northwest of Manchester.  It lies at the southern edge of the West Pennine Moors with the M61 motorway passing close to the south and west.  At the 2011 Census, Horwich had a population of 20,067. Adlington is a small town and civil parish in Lancashire, England, near the West Pennine Moors and the town of Chorley.  Six miles northwest of Bolton, it became a separate parish in 1842 then grew into a town around the textile industry.  It had a population of 5,270 at the 2001 census, but in the last decade this has risen by over 2,000 more people to 7,326.  The measured population at the 2011 Census was 6010. Black Brook in Lancashire has its source at Great Hill in the West Pennine Moors.  The water is acidic due to a high level of peat in the uplands near to Round Loaf, giving the brook its brown colour.  The young river was known as Warth Brook in olden Heapey.  A feeder stream also known as Black Brook joins near Kittiwake Road - this short and weak water course commences at Eagle Tower.  The jointed brook feeds Anglezarke Reservoir, and joins the River Yarrow in lowland Chorley at Yarrow Bridge.  The entire course of Black Brook and the River Yarrow fall within Chorley and its villages. Blackburn is a large town in Lancashire, England.  It lies to the north of the West Pennine Moors on the southern edge of the Ribble Valley, 9 mi east of Preston, 20.9 mi NNW of Manchester and 9 mi north of the Greater Manchester border.  Blackburn is bounded to the south by Darwen, with which it forms the unitary authority of Blackburn with Darwen; Blackburn is its administrative centre.  At the time of the UK Government's 2001 census, Blackburn had a population of 105,085, whilst the wider borough of Blackburn with Darwen had a population of 140,700.  Blackburn had a population of 117,963 in 2011, a massive increase since 2001.
Answer: River Yarrow