YORKSHIRE Water has been fined £6,500 for putting excessive levels of a chemical into a river in York.

The company was fined at York Magistrates' Court yesterday for a breach of consent at Naburn sewage treatment works, on the River Ouse.

Yorkshire Water pleaded guilty to one charge and was also ordered to pay full costs of £835.60 to the Environment Agency, which brought the case.

The charge was for exceeding levels of ammoniacal nitrogen, which comes from the discharge of sewage effluent.

High levels of this chemical can adversely affect the quality of water.

The court heard how Yorkshire Water has consent from the agency to discharge treated sewage effluent from the sewage treatment works at Naburn Lane, Fulford, into the River Ouse.

Agency officers carry out routine tests to ensure no limits - including those of ammoniacal nitrogen - are being breached at the site.

The maximum amount of ammoniacal nitrogen allowed is six milligrams per litre and Yorkshire Water is not allowed to breach that limit more than three times in a year.

But the company breached the level four times between December 5, 2005 and March 7, 2006.

Magistrates accepted that Yorkshire Water co-operated with the agency throughout the investigations and entered an early guilty plea.

They also noted there was no evidence of long-term damage to the River Ouse and said they did not believe that Yorkshire Water committed the offence deliberately or recklessly.

The court was reminded of an earlier conviction made against Yorkshire Water for an identical offence on April 9, 2003. The company was fined £5,000 and ordered to pay costs.

Speaking after the case, Tessa Brooks, environment officer at the agency, said: "It is disappointing that this is the second time where legal action has been brought against Yorkshire Water.

"However, we are pleased that they are now building a new treatment plant which we hope will protect the environment in the future."

11:44am today