Anglian Water and a contractor have been fined a total of £60,000 after raw sewage leaked into a river killing more than 2,400 fish.

They were also ordered to pay £30,000 costs.

Environment Agency investigators found that the watercourse had been polluted for 1.6 km and that at least 2,413 fish died.

Among the species killed by the sewage were roach, bream, pike and European Eel. This species is currently listed as a “critically endangered” species under the International Union for the Conservation of Nature.

Untreated sewage could have been discharging into the river for up to 10 hours.

Levels of ammonia monitored downstream from the discharge were found to be 200 times higher than average water quality standards.

The problems arose on December 27, 2018, when a sewer owned by Anglian Water collapsed.

They hired Danaher and Walsh to fix the problem temporarily.

Danaher and Walsh set up an over-pumping system to pump the sewage back into the drainage system.

However, it became blocked with rag; items that shouldn’t be flushed like baby wipes.

A few days later it failed leading to sewage ending up in Stanground Lode, five miles from Whittlesey and on the outskirts of Peterborough.

An Environment Agency spokesperson said: “Neither company reported the incident to us.

“Instead, a concerned member of the public called the incident hotline.”

In mitigation, Danaher and Walsh said it would have been unable to predict how much rag would be flushed in this time.

It said that it had never come across a blockage like that seen at Stanground in 30 years of operating.

Both companies appeared before Peterborough magistrates on June 1 where they both pleaded guilty.

They were charged with causing an illegal sewage discharge which polluted the Stanground Lode.

Anglian Water were fined £50,000 and told to pay £24,387.58 in costs. Danaher and Walsh were fined £10,000 and told to pay £5,000 in costs.

Yvonne Daly of the Environment Agency said: “We are disappointed with the fine issued in this case and would like to see higher penalties to really deter polluters from future offences.

“Both companies in this case failed in their environmental duties, leaving to a devastating impact on the local biodiversity.

“We are grateful to the vigilant members of the public that did report the pollution.”