Thousands of dead fish had to be cleared from the lake and stream
A water company has been fined £20,000 after admitting polluting a nature reserve on the Hampshire border.
The Chase at Woolton Hill near Newbury, Berks, was sealed off in 2006 after leaked effluent polluted a lake and a stream killing thousands of fish.
Thames Water admitted the leak came from a burst 35-year-old sewage pipeline from a pumping station.
The company was fined £20,000 and ordered to pay costs of £20,211 at Reading Crown Court on Tuesday.
An Environment Agency spokeswoman said the raw sewage caused oxygen levels to drop and ammonia to rise killing thousands of fish including brook lamprey, brown trout, bullhead and native crayfish.
Environment officer Alison Love said: "When I first arrived at the stream I was struck by the smell of raw sewage.
"The water had turned a cloudy orange colour and the stream bed was covered in slimy sewage fungus. Thousands of fish, including some important and rare species, were dead or in distress, gasping at the surface of the water.
"This incident destroyed the ecology in moments.
"A company of Thames Water's size and environmental commitment should have had safeguards in place to prevent this sort of incident, which was environmentally devastating."
A Thames Water spokesman said: "We admitted liability very quickly.
"As soon as we found out, we took action and co-operated with the Environment Agency.
"Since then our track record has been excellent, all our treatment works are working at 100% compliance."
A second offence of polluting the National Trust-owned Penwood Stream, between 17-20 February, 2007, was taken into consideration by the court.