Sewage spills ‘causing catastrophic harm’ to UK’s unique chalk streams
Sewage spills are causing “catastrophic” damage to waterways and turning rare chalk streams into “open sewers”, according to the man responsible for looking after a river in the Thames Valley.
Sam Marshall, who is employed as river keeper, worries that the Kennet and other waterways will be dead within a decade because water companies keep pumping sewage into them.
“The long story short is rivers have been kept by river keepers for fishing and wildlife for about 200 years. The way it’s going at the minute, the rivers have got five to 10 years,” he told i.
River keepers are employed by private estates to maintain waterways and look after habitats for fish and other aquatic life.
Mr Marshall, 32, has been a river keeper for 10 years, including eight years on the Kennet – a tributary of the Thames that flows through the North Wessex Downs – and said this winter has been the worst for sewage spills that he has ever seen. It is particularly worrying given that the Kennet is a chalk stream, which is a globally rare habitat.
“What the sewage does is it just chokes the riverbed,” said Mr Marshall. “With the high levels of ammonia and nitrates coming from the sewage, we get a filamentous algae which then smothers the weed.
“The weed in the river, called ranunculus, is a really, really important weed… It produces more oxygen than any other plant, it supports more invertebrate life than any other plant, it’s the fishes’ favourite place to live, it’s the swan’s food.
“And basically it gets covered with black gunk and suffocates and dies then that whole area will become devoid of life.”
Mr Marshall said this winter is “definitely” the worst he has seen for sewage spills due to the continuing wet weather.
Thames Water’s sewers have struggled to cope with rising groundwater levels, which can seep into cracks in the firm’s underground pipes and overwhelm them. Water companies are permitted to discharge untreated sewage into rivers from points known as storm overflows during times of exceptional rainfall to prevent their infrastructure from becoming overwhelmed and waste backing up into people’s homes.
But public concern is mounting over how often this is happening, with water companies being accused of not investing enough in infrastructure to prevent spills.
England is home to 85 per cent of the world’s chalk streams – including the River Kennet – which are hotspots for invertebrate and fish life due to their cold, steady flow of calcium-rich water. David Attenborough described chalk streams as “one of the rarest habitats on Earth” in his recent BBC series Wild Isles.
But conservationists have been sounding the alarm over the threat to chalk streams due to sewage pollution and over-abstraction for drinking water in the summer.
A spokesman for Thames Water said: “We’re sorry that customers have been affected as our sewers have become overloaded by floodwaters in the Aldbourne and River Kennet area.
“The excessively heavy rain that the region has experienced means the groundwater and river levels remain very high in this area and the ground is saturated.
“A significant amount of this water is entering the local sewer system and has caused flooding.
“We are working hard to keep our sewers flowing and to prevent further flooding. In Aldbourne square we have deployed a filter unit which uses a pump to take the excess water out of our foul sewer, so it can be screened.
“We regularly monitor the water quality in the River Kennet and keep the Environment Agency updated.
“There are multiple causes of pollution which affects rivers and taking action to improve the health of rivers is a key focus for us.
“We recently completed a £5m upgrade to Hungerford sewage works and we’re completing a £2m upgrade at Kintbury. We also have plans to upgrade our Ramsbury and Marlborough sewage treatment sites.”