‘The eels were climbing out of the water to die’: why did every fish in this idyllic lake perish overnight?

When Alistair and Diane Gould bought Furnace Brook in 2013, they had big plans. It was an idyllic spot: a stream-fed fishing lake nestled in a secluded valley in the High Weald, East Sussex, surrounded by woodland and fields. “People loved to come fishing here because it’s so beautiful,” says Diane. “Some of them had been coming for so many years that they got to know the individual fish.”Diane moved here from Kent in 2000, when Furnace Brook was owned by a distant relative. Her two younger sons, then 10 and 14, flourished. They would chat to the anglers about the fish they were catching and throwing back in, and sell them bacon sandwiches. Her elder son, Simon, moved from London to join them in 2006 and became a keen angler himself, and then the fishing manager, or bailiff, looking after the fish and the landscape around the lake.Ed, a local angler, at Furnace Brook. Photograph: Alicia Canter/The GuardianDiane, who is 68, and Alistair, 69, met in 2008. After Diane’s relative died, they decided to buy the property. Alistair, an ecological consultant with a background in low-carbon design, had drawn up a plan to restore the entire ecosystem of the eight-hectare (20-acre) site. But two years ago, their plans were blown out of the water.On the morning of 20 June 2024, Alistair and Simon walked down to the lake and noticed dead fish floating on the surface. “We looked at it and thought: ‘This is a bit odd,’” says Alistair. On further inspection, almost everything in the 2.4-hectare lake was dead. “It brings tears to my eyes,” says Diane. There were at least 15 species of fish in the lake, she adds: carp, tench, bream, roach, trout and some large eels. “You get a sort of relationship with them, as living beings.” The larger fish even had names.“It was very traumatic for us all,” Alistair continues. “Obviously for nature directly, but also seeing all these fish on the surface and the fact that Simon has been a fishery bailiff here for 15-plus years and these are his babies, and he’s just seeing them all curl up and die.”Massacre … 15 trailer-loads of dead fish were removed from the lake. Photograph: Courtesy of Furnace BrookDiane continues: “More than 2,000 fish were dead. Plus, the ones we don’t know about that sank to the bottom. The eels were climbing out of the lake to die.” Eels are pretty hardy, says Alistair; they can even travel over land if they need to. To see them gasping and dying on the banks was heartbreaking. “It was apocalyptic.”At first, the Goulds thought it must be their fault, that they had mismanaged the fish stocks somehow. But when Alistair walked to the top of the lake, he saw that Clippenham stream, which feeds the lake, was also full of dead fish. “That’s when I twigged: ‘This isn’t us. There’s something else going on.’” It seemed clear to him that pollution was coming from somewhere upstream. “All down the stream, our friends were finding dead fish: lamprey, brown trout, freshwater mussels,” says Diane. The stream runs to the Pevensey Levels on the south coast, where water is extracted for drinking and agriculture.‘The eels were climbing out of the lake to die.’ Photograph: Courtesy of Furnace BrookThey immediately called the Environment Agency (EA), the body responsible for the “protection and enhancement” of the environment in England, which visited two days later and declared it a Category 1 incident, the most severe kind, meaning it had “a serious, extensive or persistent impact on the environment, people or property”. The Goulds and their team removed 15 trailer loads of dead fish from the lake, which the EA advised them to bury. Their angling business was gone overnight. They estimate they have lost £500,000 in income so far. A biologist later estimated that the lake would take 10 to 15 years to recover. “It’s not just the loss of money,” says Alistair. “It’s the loss of the ecological function.”The story of Furnace Brook could be Britain in microcosm. We take pride in our rural heritage, in the natural beauty of our countryside, but the illusion that it is an unspoilt, unchanging idyll is becoming ever harder to maintain. River pollution has become a national scandal. The release of sewage by privatised water companies – illegal but persistent and apparently unpoliced – has devastated landscapes throughout England. Often, we register this in terms of how picturesque our rivers are or how safe they are to swim in – how the pollution affects us directly – but beneath the surface, decades of pollution have decimated how much life they can support. According to government statistics from 2025, just 14% of England’s rivers and lakes have a “good ecological status” and every one of them is polluted with chemicals.Illegal dumping has become a separate scandal, the scale and effects of which also seem beyond authorities’ control. In the past 12 months, there have been high-profile cases such as the 150-metre-long mountain of rubbish “discovered” in Kidlington, Oxfordshire, or the 35,000 tonnes of rubbish dumped in Hoad’s Wood, Kent, the latter of which cost an estimated £15m to clean up. In August, Andy Burnham visited another huge, foul-smelling illegal dump, in Midland Road, Bradford, where he vowed to take action, declaring: “The days of making easy money out of waste are over.” He has a (waste) mountain to climb. Over the past two decades, successive governments have loosened environmental regulations and removed protections – not least by neutering the EA.The aftermath … Simon Dole, Furnace Brook angling coordinator and coach, holds one of the dead fish. Photograph: Courtesy of Furnace BrookThe fact that this is happening in the countryside, sometimes in isolated areas, makes it hard to monitor or police. Furnace Brook is a symptom of all these problems, although it could also become a model for how to overcome them. The Goulds are working on a plan not only to restore the landscape, but also to show how we could reset our relationship to it in a more sustainable, nature-friendly, community-oriented way.In the case of Furnace Brook, the water companies were not to blame. So the Goulds set out to discover what was. “I thought: ‘I bet I know exactly where that’s come from,’” says Jack (not his real name), Furnace Brook’s former ecological consultant, who has worked in the area for decades and knows the landscape intimately. He remembers walking up Clippenham stream two days after the pollution event. “It was hot weather and the whole of the valley stank. It smelled of dead fish and aquatic life. I thought: ‘It’s probably something that’s come off another property. And if any of the properties around here are likely to be doing something unpleasant like that, I’ll put money on it that I know which one it was.”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.Jack followed the polluted tributary up through Ann Wood, a small pocket of ancient woodland on Morgans Farm. The source of the tributary seemed to be a large hole or pit at the north-west corner of the wood, in a cleared area, accessible by heavy vehicle. In one council document, it is referred to as a “slurry lagoon”. Shortly after the pollution incident, this hole was filled in and covered with waste soil. When I visited in September 2025, the area where the hole had been was obscured beneath a stack of hundreds of plastic-wrapped hay bales.When EA officers visited in the days after the pollution event, they were shown the devastation and the suspected source of the pollution. They took water samples from various locations. One officer also visited Morgans Farm. The EA has the power to investigate and prosecute those in breach of environmental protection laws, which can result in fines or even imprisonment for offenders, but the process is notoriously slow. Investigations can take years and rarely result in meaningful penalties. More than two years later, the EA has yet to take action over the incident at Furnace Brook.‘Bacterial cheese’ … the fishing lake at Furnace Brook with scum from pollution on its surface. Photograph: Courtesy of Furnace BrookIn the interim, Alistair and his team took matters into their own hands. They bought equipment to test the water for factors such as dissolved oxygen, dissolved solids and conductivity. They also tested for heavy metals, such as lead, cadmium, arsenic and mercury, which are usually a byproduct of industrial, rather than agricultural, processes. You can do crude tests for them with a paper strip that changes colour from orange through to dark purple. When they tested the water coming from Morgans Farm, it was “off the chart”, says Jack. “This went about as deep into the purple as you possibly could go.”A year later, in July 2025, Furnace Brook sent samples of water collected from the lake to an independent testing lab. The results still found unusually high levels of heavy metals, ammonia levels that were “well outside acceptable limits for any freshwater life” and nitrogen levels that were “toxic to all aquatic life”.What was going on at Morgans Farm? Quite a lot, according to its neighbours. Going by planning statements submitted by Morgans Farm, the owners farmed “a mix of cattle and sheep spread out over 243 hectares throughout Sussex”. Several large