Precautionary signs after blue-green algae found at Connaught Water

Epping Forest managers are warning visitors against swimming, fishing or taking dogs into Connaught Water after a suspected outbreak of blue-green algae on 18 October.

The City of London Corporation, which conserves the site, has asked the Environment Agency to investigate and are awaiting results.

Blue-green algae naturally occur in inland waters, estuaries and the sea – and they are important contributors to the biology of fresh and marine waters.

But where high levels of phosphorus combine with other factors experienced in the recent heatwave - like increased sunlight and temperature - the numbers of blue-green algae can rapidly increase. These are known as ‘blooms’.

Blooms can have a temporary negative effect on the appearance, quality and use of the water. They can produce toxins which can harm and be potentially fatal for wild animals, farm livestock and pets.

Precautionary signs have been placed at the site warning people against fishing, swimming or letting animals in the water while managers monitor the situation with the Environment Agency.

The most effective method for controlling the growth of algae is to reduce the overall levels of nutrients which support its growth, and the blooms are expected to naturally clear in the coming months.

A spokesperson for the City of London Corporation said:

“This is a natural process and we need to allow time for the algae at the lake to clear on its own. In the meantime it’s important that visitors and their pets do not enter the water.

“At the moment it is safest not to let your dog swim or drink in the lake. If they do come in contact with the water, wash them thoroughly with fresh water and dry them to prevent them grooming themselves and ingesting any potential algae. If you are concerned, take your dog to a vet.

“If you come in to contact with blue-green algae, seek medical advice if you have any health effects.”

The City of London Corporation manages 18 major green spaces in London and south east England, including Epping Forest, Hampstead Heath, and over 200 smaller ones in the Square Mile.

They include important wildlife habitats, sites of scientific interest and national nature reserves and they are protected from being built on by special legislation.

These green spaces, most of which are charitable trusts, are funded by over £28million a year from the City Corporation, and are run at little or no cost to the communities that they serve.


Media enquiries

Laura Simpson, Media Officer, City of London Corporation

T 020 7332 3654

M 07738862229

Notes to editors

The City of London Corporation is the governing body of the Square Mile dedicated to a vibrant and thriving City, supporting a diverse and sustainable London within a globally-successful