On Friday 24 September 2011 anglers on the River Neath in South Wales reported that a stretch of the river between Abergarwed and Neath Town had turned a muddy orange colour, and that a number of fish could be seen to be visibly in distress.
An angler by the River Neath.
An investigation by the Environment Agency Wales revealed that the pollution was entering the river from the Garwed Brook, and found a number of dead fish, small bullheads, due to oxygen depletion. The river was pH tested, but was not found to have been acidified sufficiently to warrant remedial action. The Environment Agency concluded that the source of the pollution was almost certainly a mine working; of which there are a number in the area, mostly disused. The worst of the pollution has now cleared, but the Environment Agency are working with the Coal Authority to find the source of the contamination, with the hope that any future incidents can be prevented.
Pollution from the Garwed Brook entering the River Neath.
This is the second incident in South Wales relating to rainfall entering disused mines this month; on the 15th four miners were killed at the Gleision Colliery near Swansea after water entered the mine from a flooded, disused working. This is somewhat of a mystery as Wales has experienced an unusually cool and dry summer. One of the predictions made by climate scientists studying the effects of global warming is that rainfall patterns will alter as the world warms. This is likely to lead to an increase in the number of incidents of this kind, as water levels change in ways that are hard predict. However there is no evidence to suggest that these incidents are the result of global warming.
See also Disaster at the Gleision Colliery.