Our rivers in South East Wales have their heads in the hills and their feet in the towns. All of the major rivers have their source in the mountainous land which runs in a line from Carmarthen to Monmouth containing the wonderful Brecon Beacons, Mynydd Llangynidr, Mynyydd Llangatwg, Mynydd Blaenrhondda, Mynydd Y Gelli and Mynydd Pwllyrhebog to name just a few. Rivers run through Bridgend, Barry, Cardiff, Methyr Tydfil, Caerphilly, Pontypridd and Newport, all major towns and cities with large populations. Two minor river systems drain the lowlands of the Vale of Glamorgan, the River Thaw and the Cadoxton River.
Carboniferous limestone forms the predominant rock of the area and despite the considerable acidic rainfall over the mountains - around 850mm per year - the alkaline lime dissolved in the river leads to an abundance of aquatic invertebrates, providing rich feeding for the wily brown trout and juvenile salmon which are indigenous to the fast flowing waters.
Every river in the region eventually flows into the vast estuary of the River Severn, famous for its enormous tidal range and powerful currents. The estuaries of the Ebbw and Rhymney run through deep muddy channels at their confluence with the Severn estuary which creates important feeding grounds for wading birds, whilst the Taff and Ely feed into the artificial lake of Cardiff Bay, formed by the completion of the barrage in 1999, and then overflow to the sea.
The valleys the rivers run through are steeped in the history of Wales and have witnessed the massive changes brought about by the industrialisation of a largely agricultural community. The farming continues to this day but is nowhere near as important economically as it was in the past.
Rivers literally and infamously ran black with coal dust from the mines that supplied the power when the woods and water of the region were exhausted by the scale of the demands created by the railways, the factories and the people who flocked to South East Wales in their thousands.The two Rhondda Valleys, Fawr and Fach housed around 3,000 people in 1860. By 1910 the population had soared to 160,000.
The River Ebbw had a particularly intense industrial epoch with works such as Abertillery Colliery and manufacturers like Ebbw Vale Steelworks - once Europe's largest - lining the valley and contributing to the elimination of nearly all life in the river. The lives of the workers whose houses were crammed into the land alongside the production centres were similarly under threat from the atmospheric pollution which filled the valley.
Heavy industry in South East Wales has declined rapidly through the late 20th Century although the communities themselves have expanded. Major investments in water treatment coupled with legislation regulating standards for waste entering our rivers have generated a revival of their ecologies. Trout and kingfishers are back in these river systems today and the aquatic fly life can be surprisingly prolific.