A raw sewage discharge which lasted 23 hours and killed 5,000 fish in a Northamptonshire river.has cost Anglian Water a total of £560,170 in court.

 Around 6 million litres of raw sewage was discharged into the River Great Ouse at Brackley, Northamptonshire. It killed thousands of fish and spread 12 kilometres down the River Great Ouse.

The discharge, from the emergency overflow at the pumping station, started just before 6pm on 24 May in 2017. It was not stopped until around 5pm the next day, 23 hours later.

Electrical faults caused the pumps to stop - a failure of the early warning alarm system, put in place to alert Anglian Water staff of an issue, meant the discharge went unnoticed.

The pollution was found to have stretched 12 kilometres down river. Fish including brown trout, chub and pike were killed, as well as smaller species such as bullhead, dace, stone loach, minnow, gudgeon and 79 brook lampreys. Dead signal crayfish were also observed.

Anglian Water pleaded guilty to a breach of permit. They were ordered to pay a fine of £510,000, costs of £50,000 and a victim surcharge of £170 at Peterborough Magistrates’ Court on 12 January 2023.

Environment Manager at the Environment Agency, Andrew Raine, said:

“The environmental impact of this pollution was substantial, resulting in a large scale fish kill and affecting 12 kilometres of the upper River Great Ouse.

“Polluters should always be held to account, as much as our resources allow, we will always investigate significant pollution incidents and bring those responsible before the courts.

“We are grateful that the level of fine acknowledges the damage to the river ecosystems that this sewage spill from Anglian Water has caused.”

The court heard how an electrical failure caused the pumps to stop working and another electrical fault prevented the back-up system from working. This was further compounded by the failure of an alarm system which was meant to notify staff there was a discharge.

Brackley Terminal Pumping Station pumps sewage from within the town of Brackley to be treated at sewage works 1.3 kilometres to the east of the town.

A number of incidents were reported to the Environment Agency by members of the public and landowners, including numerous sightings of dead fish on the river.

Investigating Environment Agency officers also reported finding the bed of a watercourse that flows into the river was completely covered in sewage debris.

There were also fresh waste materials more than 4 inches up the banks, indicating levels had been higher recently despite no rain for the last few days.

The Environment Agency has significantly increased the monitoring and transparency from water companies via Event Duration Monitoring whichmeasures how often and for how long storm overflows are used.

The Agency has increased the number of overflows monitored across the network from 800 in 2016 to more than 12,700 in 2021 - the equivalent of almost 9 in 10 storm overflows now with monitoring devices. All 15,000 overflows will have them by the end of 2023 and all the data is published online.

The Environment Agency has also asked companies to install new flow monitors on more than 2,000 wastewater treatment works to identify what is happening at those works during the sewage treatment process itself. This has led to a major investigation, announced in November 2021, with the Environment Agency requesting more detailed data from all wastewater treatment works.