Steve Rose investigates a catastrophic pollution incident at Furnace Brook, a fishing lake in East Sussex, where thousands of fish suddenly died and the local ecosystem collapsed. Neighbours suspect pollution from nearby Morgans Farm, and Rose examines whether their concerns are justified. In doing so, he uncovers broader national problems with water pollution, illegal waste dumping, and the limited power and resources councils and regulators have to tackle them.

He headed about half a mile up the valley to a tributary joining the stream from a neighbouring property named Morgans Farm. “You could clearly see the water upstream [of the tributary] was totally normal, a sandy colour with clay silt in it, and what was below it had gone a blue-black colour. You could see dead brook trout, wild eels, and there was a dead crow or raven, which may well have eaten something poisonous from the river.” In some places, he says, there was a thick layer of blue-grey scum on the water, which he later learned is sometimes called “bacterial cheese”. “There’s so much nutrient [sic] in the water that it allows for a bacterial colonisation explosion.” The bacteria take up all the oxygen, which causes most of the fish, especially the older, larger ones, to die.