THAMES WATER has been ordered to pay £15,000 after a raw sewage leak in Witney, which killed hundreds of fish.

Untreated sewage flowed into Emma’s Dike, killing about 650 fish in December 2007.

Thames Water pleaded guilty at Banbury Magistrates’ Court to two charges under the Water Resources Act.

The firm was fined £10,000 and ordered to pay £5,074 prosecution costs.

The court heard it will take three years before the waterway is back to normal with a healthy fish population.

Emilie Vonck, of the Environment Agency, said: “Water companies have a statutory duty to maintain their sewers, which Thames Water had not done in this case. It sends a clear message to other companies that if you fail in your environmental responsibilities you may be prosecuted.”

The court heard Thames Water was told about the pollution but cancelled work planned to fix the leak.

A week later the Environment Agency discovered the water had turned milky white and 650 dead fish – half of all fish in the stream.

Tests revealed high levels of ammonia and other pollutants, The incident was classed as the most serious type of pollution.

It was the second time Thames Water has faced legal action over Emma’s Dike and other streams after being fined £100,000 for a similar leak five years ago.

A Thames Water spokesman said: “We take our environmental obligations very seriously and fully accept the fine.

“Regrettably, mistakes were made on our part and measures have been put in place to prevent this happening again.

“Since this incident, we have installed an alarm in the sewer that will alert us to any problems.”