The chair of a local wildlife charity has accused Thames Water of making the river ‘environmentally dead’ after untreated waste was pumped into Marlow's waterway for 10 hours this week.

According to the water company’s event duration monitoring (EDM) map, waste was discharged into the Thames in Little Marlow for 10 hours yesterday, between 8:42am and 6:44pm.

Verity West, chair of Wild Marlow, said it was “beyond belief” that “toxic sewage dumping after every heavy rainfall is (still) considered an acceptable practice”, especially criticising what she described as a “catastrophic” impact on local wildlife.

She added: “We are in a nature crisis and our country, one of the most nature-depleted in the world, is supposed to be committed to stopping the decline and restoring nature by 2030.

“However, our water companies appear to have facilities that are not fit for purpose, and no one is holding them to account.

“It won’t be long before the River Thames is declared ecologically dead again.”

It’s the latest in a series of spillages near the Little Marlow Sewage Treatment Works and comes after TV naturalist Steve Backshall found “horrifying” levels of bacteria including E.Coli and norovirus in water samples taken downstream of the plant in April.

Yesterday’s spill was likely caused by the ongoing spell of bad weather hitting Buckinghamshire and other parts of the UK, with some seeing more than the monthly average of rainfall in 24 hours, disrupting road and rail networks.

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A spokesperson for the company has previously attributed “unacceptable” sewage discharges in Marlow to “excessively heavy” rain causing high groundwater and river levels.

They said: “These issues combined mean there is nowhere for further rain or other flow from nearby land to go and therefore our sewers are struggling to cope.

“The overflows are designed to operate automatically when the sewer network is about to be overwhelmed, which then releases diluted wastewater into rivers, rather than letting it back up into people’s homes.

 “We have published plans to upgrade over 250 of our sewage treatment works and sewers across the Thames Valley, including Little Marlow Sewage Treatment Works. This will improve our ability to treat the high volumes of incoming sewage and reduce the need for overflows during wet weather.”

Thames Water, which serves about 16 million people, is currently in the grip of a funding crisis and has only enough cash to continue operating until May 2025.

It also has more than £15 billion of debt, and regulator Ofwat has said it intends to appoint an independent monitor to supervise the company as it attempts a turnaround.

If the fresh cash is not raised, however, Thames Water faces a potential nationalisation next year, something the Labour government has said it is keen to avoid.