The extent and scale of the industrialisation that took place at a time when there almost no environmental controls in place created a legacy of chronic contamination of land and water by a great range of toxic and dangerous pollutants. The River Tawe was already being polluted by the coal mining industry and suffered badly. Even worse affected was the stream that meandered through the lower half of the valley, the Nant y Fendrod. Records about the history of this stream are sparse but it appears likely that for over 100 years most of the water was taken from this stream to be used in industry and its channel became the repository of much of the liquid waste from the various industries. In addition rainfall seeping through the growing waste tips added further burdens of by-products and waste materials.