Editing River Afan (section)

==Tributaries==

===River Corrwg===
The Corrwg is one of the Afan's principal tributaries. Its length is approximately 11&nbsp;km, and its source lies above the village of [[Glyncorrwg]], in the hills south of [[Glyn-neath]]. It has a major tributary, [[Afon Corrwg Fechan]], as well as numerous tributary streams. Several waterfalls exist along the river's course. Although the water is clear today, discharge from the many collieries along its lower reaches led to significant pollution. Minor discharge sometimes leaks from the Glyncorrwg colliery, although its effects do not have a noticeably detrimental effect on the river.

===River Pelenna===
The Pelenna, a major tributary that meets the Afan at [[Pontrhydyfen]], suffered more severely from pollution than the main river because of the sulphur-rich coal that was produced by the mines in that area. As a result, the abandoned coal mines continued to discharge [[acid mine drainage]] rich in iron and highly acidic. This turned much of the river orange down to the confluence of the Pelena with the main river Afan. The orange colour could often be seen as far down stream as [[Pontrhydyfen]]. There were a number of collieries contributing to the pollution although the major source was the Whitworth Colliery.<ref>{{cite web|url=http://freepages.genealogy.rootsweb.ancestry.com/~cmhrc/lom08glamw1.htm|title=LIST OF MINES in Great Britain and the Isle of Man, 1908|publisher=Coal Mining History Resource Centre|access-date=23 April 2009}}</ref> At the height of coal extraction in the valley, there were several deep pits and numerous levels. This pollution is now much mitigated<ref>{{cite journal |doi=10.1111/j.1747-6593.1998.tb00150.x | volume=12 | title=Proceedings of CIWEM Conference on Minewater Treatment Using Wetlands | journal=Water and Environment Journal | pages=68–69}}</ref>
following extensive work promoted by the [[Environment Agency]] in the creation of [[Constructed wetland|engineered reed beds]] to treat the mine drainage.

===Nant Ffrwdwyllt===
[[Nant Ffrwdwyllt]] was a small tributary of the Afan, just under 8&nbsp;km and joining the Afan close to the sea. It was diverted in the 18th century into the ironworks at what was to become Port Talbot, to provide a source of water. It remains diverted, flowing into [[Port Talbot Docks]].