The river rises from a series of springs on the northern fringe of Fairwood Common, between the towns of Three Crosses and Dunvant.

Being far from the industrial hub of Swansea, the river was not subject to much pollution from the docks and copper works in the city.

The vast oyster beds (which gave the area of Oystermouth its name) disappeared, and the variety of birds that once came to the river mouth to feed were driven away.

However, since the water quality in Swansea Bay has improved, the fish and birds are returning to the river in droves.

The steep-sided, wooded river valley dates from glacial times and contains a wide variety of vegetation and habitats - woodland, grassland, and wetland.