Update: 1300 hrs Sat May 9th

A number of readers have witnessed a large amount of dead fish in the River Stort.

One reader (thanks Rachel) was out running this morning (Saturday) and took the photograph below.

We think the press release issued by Epping Forest District Council may explain what has been happening.

A natural phenomenon

ALGAE blooms are a natural phenomenon. Under certain weather conditions it can bloom in large volumes, cutting off the oxygen supply in rivers and lakes.

If the outbreak is serious, it can lead to the death of fish and other organisms. Algal blooms can also be toxic to wild animals, people and pets.

Environment Agency Officers will continue to monitor the situation and deploy additional resources if necessary. Members of the public are advised to stay away from any water courses showing signs of a bloom – typically cloudy or less clear green water and dead fish.

It can also look blue-green or greenish-brown. Scums can form during calm weather when several bloom forming species rise to the surface. This can look like paint, mousse or small clumps.

https://www.gov.uk/government/publications/algal-blooms-advice-for-the-public-and-landowners/algal-blooms-advice-for-the-public-and-landowners