The Environment Agency has prosecuted Yorkshire Water for illegally discharging sewage effluent into the Potter Carr Nature Reserve.

Photo: pollution on the Mother Drain and how it was contained

On 8 September 2021, at Sheffield Magistrates Court before District Judge Redhouse, the company was fined a total of £150,000 and ordered to pay £36,506.25 costs.

Yorkshire Water Service Limited pleaded guilty at an earlier hearing to 2 charges under the Environmental Permitting (England & Wales) Regulations 2016. The charges were causing sewage sludge to enter a tributary of the Mother Drain and breach of permit condition relating to ammoniacal nitrogen levels in their final treated sewage effluent.

Representing the Environment Agency, Rebecca Chalkley told the court that Yorkshire Water holds an environmental permit which authorises water discharges from Balby Sewage Treatment Works under a number of strict conditions.

On March 28 2017, Yorkshire Wildlife Trust reported that Mother Drain at the Potter Carr Nature Reserve, had become discoloured and smelt of chemicals. The site is of Special Scientific Interest.

Environment Agency officials attended and confirmed pollution of the Mother Drain. They saw small pieces of toilet paper floating in the water, which looked grey, and sample results confirmed high levels of ammoniacal nitrogen in the water.

Due to the severity of the pollution the Environment Agency requested the Internal Drainage Board to switch off a pump station used for land drainage. It was switched off to prevent polluted water passing downstream to the River Torne, they also instructed abstractors to cease abstracting water. This included Doncaster Golf Club.

Once the Environment Agency contacted Yorkshire Water, they confirmed that there was an issue at Balby Sewage Treatment Works.

Officers attended Balby Sewage Treatment Works on March 29 2017 and took a sample of treated sewage effluent which contained ammoniacal nitrogen above the permitted maximum limit.

During the site visit Yorkshire Water explained that a valve failure had led to a settlement tank on site draining sewage sludge. The sludge drained inside a building and onto surrounding ground.

Later, in an interview under caution, Yorkshire Water explained that the valve failure happened on Monday 27 March 2017. However, the utility did not contact the Environment Agency because they thought effluent was contained on site.

The company further added that electrical damage caused by the incident affected parts of the works and disrupted the biological treatment processes. This resulted in a deterioration of the treated sewage effluent quality.

In response to the incident Yorkshire Water placed aeration equipment in the Mother Drain. The Environment Agency continued to investigate and monitor the effects of the pollution for over a week. There was no sign of dead or distressed fish.

In court, District Judge Redhouse found the culpability of Yorkshire Water to be ‘high negligent’ due to the fact the incident could have been avoided if there had been a drain survey at the site and if the valves had been checked.

She stated that whilst the general public may consider the actions reckless when applying common everyday language, in criminal legal terms it was negligent. She described it as “very negligent”.

A spokesperson for the Environment Agency said:

“Water companies are aware that their activities have the potential for serious environmental impacts, and they know that we will take action when they cause pollution.

“In this case Yorkshire Water has failed the environment, customers and the system of environmental laws the public puts its trust in.”