Yorkshire Water has been fined £3,000 by Rotherham magistrates for polluting the River Rother.
The company, of Halifax Road, Bradford admitted breaching its permit to discharge into the river in February, 2006, and was ordered to pay £1303.17 costs following the court hearing on February 14.
Trevor Cooper, prosecuting for the Environment Agency, said officers discovered the problem after taking a routine sample of the final effluent from the treatment works at Long Lane, Treeton.
Yorkshire Water’s permit states that it cannot exceed 80 milligrams per litre of Biochemical Oxygen Demand (BOD) in the effluent that goes into the River Rother. However, analysis of the sample showed that BOD was 165 milligrams. BOD is used to measure the extent to which water is polluted with organic compounds.
Although a lack of oxygen in the water can kill aquatic life, Mr Cooper told the court that in this case there was no evidence of any environmental impact on the river.
He told magistrates that Yorkshire Water had said the problem had been due to a mechanical breakdown.
In mitigation, Yorkshire Water said the treatment plant had a good service record and the company had recently spent £47,000 refurbishing it.
After the prosecution, environment officer John Hancox said: “We draw up permits to help protect the environment from pollution. Water is becoming more and more of a precious resource and we need to protect what we have got. Companies can’t afford to make mistakes.”