Last reviewed 14 September 2021

Yorkshire Water has been fined a total of £150,000 and ordered to pay £36,506.25 costs, after pleading guilty to illegally discharging sewage effluent into a national nature reserve.

The charges relate to Balby Sewage Treatment Works in March 2017 and involved sewage sludge entering a tributary of the Mother Drain, breaching permit conditions for ammoniacal nitrogen levels in their final treated sewage effluent.

Potter Carr Nature Reserve is a site of Special Scientific Interest (SSSI) and remnant of a vast fenland that once stretched all the way across the Humber basin to the coast. It is also home to the rare bittern and marsh harriers.

Yorkshire Wildlife Trust, which manages the site reported the incident to the Environment Agency (EA). Officials confirmed pollution including "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 EA requested the Internal Drainage Board to switch off a pumping station used for land drainage, to prevent polluted water passing downstream to the River Torne. Water abstractors were also instructed to cease abstracting water. 

According to Yorkshire Water Services Limited, a valve failure was the main cause of the problem but decided not to contact the EA 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 court, District Judge Redhouse found the culpability of Yorkshire Water Services Limited 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.

A spokesperson for the Environment Agency said the company had; “failed the environment, customers and the system of environmental laws the public puts its trust in.”

“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.”

Yorkshire Water has now invested £640,000 in new equipment at Balby treatment works. "We take our responsibility to look after the environment very seriously and we are sorry this incident occurred," the company said.