The NRA's Northumbrian region began the investigation last November after swans began to sink on the river Tweed. An unknown pollutant washed the natural oils from their plumage. Solvents were the prime suspects.
Although it appears unrelated to the swan problem, solvent contamination was subsequently discovered by the NRA in the local Fell sandstone aquifer. The water, which was being abstracted by a company from its own borehole, contai