THAMES Water has been fined £10,000 for polluting a stream in Faringdon by allowing sewage to flow into the waterway.
Environment Agency officers visited Faringdon Stream in August and found dead fish, including chub, dace, perch and roach.
It is estimated more than 270 fish were killed by the pollution.
Oxford Magistrates’ Court heard on Friday that a breach in a Thames Water inlet pipe caused sewage to overflow and discharge into an area of woodland and then flow into Faringdon Stream. The discharge lasted for more than 48 hours, the court was told.
During the investigation, Environment Agency officers found the pipe, which was installed in 1974, had burst in the same area in September 2003.
Jack Knight, the Environment Agency’s investigating officer, said: “Rivers and water courses are an important part of the environment; they offer an essential resource for wildlife, fisheries and recreation.
“It is distressing when incidents such as this one occur and cause fairly significant environmental damage, with several hundred fish killed by this sewage spill.”
Thames Water, which admitted the offence, was also ordered to pay the prosecution costs of £4,488.
Company spokeswoman Natalie Slater said: “We deeply regret this incident. When problems like this do occur we aim to sort them out as quickly as possible.”
She said the company’s 109,000km sewerage network removes and treats four billion litres of waste water every day.