Thames Water was fined £4 million by Aylesbury Crown Court for discharging an estimated half a million litres of raw sewage into the Seacourt and Hinksey streams in Oxford on 24th and 25th July 2016.
The discharge lasted approximately 30 hours and flowed for at least 3.5 kilometres along the streams
The Environment Agency said the amount of raw sewage leached into the river streams led to the death of approximately 3,000 fish.
Thames Water told the court it had failed to carry out essential maintenance work to prevent blockages in a sewer that it already knew was vulnerable to blockages.
The court heard that the company had no system in place to identify blockages or pollution occurring and instead relied on observations by members of the public.
The UK’s largest water and wastewater company pleaded guilty to the pollution incident.
Judge Francis Sheridan said that this was yet another very serious breach of legislation in an area of outstanding natural beauty and that the waterfall of raw sewage was a disgraceful state of affairs.
Robert Davis, an attending Environment Agency Senior Officer, said: It was quite horrific. Sewage pollution was bank to bank and there was a foul stench of raw sewage.
“When we traced the source we found a waterfall of raw sewage discharging via a pipe into the streams. Amongst the dead fish, Fisheries officers observed hundreds more on the surface, suffering and gasping for oxygen.”
Responding to the court decision, Richard Aylard, Thames Water’s Sustainability Director, said: “We are deeply sorry for this incident in 2016 and the entirely unacceptable pollution that was caused to the Seacourt Stream, following a blockage of our sewer.
“We pleaded guilty at the first opportunity and accept the judgement of the Court that we failed badly by not inspecting and cleaning this part of the sewer system.”
Mr Ayland assured that things have changed and as part of a new programme the company is doing five times as much sewer cleaning as it was in 2016.
He also welcomed the announcement from Ofwat and the Environment Agency on Friday that more than 2,000 sewage treatment works will be subject to ‘major investigation’ for potential illegal sewage discharges.
Mr Ayland added: “Our view is that it’s unacceptable for untreated sewage to enter rivers, even when legally permitted and we have an unprecedented amount of investment directed towards safeguarding our rivers and streams, including spending more than £1.25 billion at our sewage treatment works during our current five-year business plan.”