900 dead and distressed fish were found floating in Whittlesey due to high levels of ammonia.

The Environment Agency said they carried out an investigation in the Kings Dyke area on September 23.

This investigation revealed low dissolved oxygen and slightly elevated total ammonia and around 50 dead fish, although more in distress.

“The Event Duration Monitoring (EDM) map showed that nearby Anglian Water pumping station had discharged for around 23 hours from Sunday September 22," said a spokesperson for the Environment Agency. 

"Anglian Water confirmed that they had suffered a pump failure. 

"Formal samples from the watercourse were taken but discharge had ceased. 

"Our fisheries team subsequently confirmed 862 dead fish, predominantly small roach with lesser numbers of pike and perch.”

“Our teams visited the site to investigate the pump failure and have collected evidence and formal samples for analysis.

"We found no further dead fish but saw evidence of fish in distress. We liaised with Anglian Water about where to deploy a mechanical aerator.

"The Middle Level Commissioners (IDB) and the local angling club were informed of this fish mortality.”

“Mechanical aeration by Anglian Water contractors has continued on site.

“Dissolved oxygen levels have improved and there has been positive observations of fish activity from anglers in the area.

“We are continuing to liaise with the site operators and Anglian Water, and updates on the incident have also been provided to the local MP.”

An Anglian Water spokesperson said: “We, like everyone, are saddened that fish have died in Kings Dyke, Stanground. 

“We will always respond to support the natural environment in an event like this, regardless of whether we believe our assets are the cause.

“We are taking it very seriously, which is why we worked throughout the weekend alongside the Environment Agency and other agencies to investigate what has happened.  

“We’ve been very open that our storm overflow operated as permitted during such heavy rainfall.

“However, this does not necessarily mean our asset activity resulted in the impact on the watercourse.

“Since the initial event we’ve found several other potential sources of pollution which do not belong to Anglian Water.

“We remain active on site in case of further rain forecasts and have extra resources on standby.”