A NABURN water treatment plant poured 10,000 cubic metres of raw sewage into the River Ouse on one day because it did not have a working stand-by pump, York magistrates heard.

It is the latest in a series of occasions in recent years when Yorkshire Water has damaged the river’s water quality.

Jane Morgan, prosecuting for the Environment Agency, said the pump was out of action and when agency officers returned a year later, it was again out of action.

She said: “Had there been a stand-by pump in place, there would not have been a discharge. It was an avoidable incident.”

Magistrates decided the case was too serious for them to deal with and committed the company to York Crown Court for sentence.

Yorkshire Water, of Western House, Halifax Road, Bradford, pleaded guilty to water pollution on August 23, 2013, and two charges of failure to comply with the environmental permit allowing it to make limited discharges into the river.

According to the charges, Yorkshire Water did not have a working stand-by pump at Naburn between March 1 and October 2, 2013, and between August 17 and September 29, 2014.

It has to have a working pump in place as a condition of its permit, magistrates heard.

Mrs Morgan said there was no discharge in 2014, though conditions were similar to August 23, 2013, when the 10,000 cubic metre discharge occurred.

Yorkshire Water was fined £6,500 in 2008 by York magistrates for polluting the Ouse at Naburn by exceeding its discharge limit and received a fine of £5,000 in 2004 for a similar offence.

In 2007 it was fined for polluting the Ouse at Hemingbrough, the third time it had pumped too much sewage into the river at the same place in 12 months.

Between November 2004 and May 2007, the water company was also convicted of four similar offences near Halifax and at Rotherham and Huddersfield and between July 2005 and May 2007 was given ten cautions for too much sewage or waste products in watercourses.