Residents urged to avoid contact with River Thames following blue-green algae blooms

Residents are being advised to avoid entering the River Thames in affected areas after blue-green algae blooms were identified at the designated bathing site and at Richmond Lock.

The Environment Agency has confirmed that the bloom near the designated bathing site is present between Sunbury Lock and Teddington Lock. Kingston Council will be installing warning signs in the area, and further updates will be provided as additional sampling results become available. We are working closely with Kingston Council and the Environment Agency to monitor the situation.

The Port of London Authority has also identified a separate bloom at Richmond Lock.

Blue-green algae can appear as green or blue paint on the surface of the water or along the riverbank. While not all blooms produce toxins, it is not possible to determine whether an algae bloom is harmful simply by looking at it, so residents are being urged to treat it as potentially toxic and avoid contact.

Lack of rainfall, combined with warmer temperatures and slower-flowing water, are contributing to the growth of blue-green algae in the river. Given the current weather forecast, the blooms may persist for several weeks. 

Public safety advice

Residents and visitors are advised to:

• Avoid bathing and swimming: Do not enter the water in affected areas until further notice
• Keep pets away from the water: Do not allow dogs or other animals to swim in or drink from the river. Blue-green algae can be fatal to pets
• Avoid contact with visible algae: Stay clear of algae on the water surface and along the riverbank, and do not touch affected water or make contact with potentially contaminated waterfowl

Anyone who comes into contact with affected water should wash thoroughly with clean water. If you or your pet becomes unwell after contact with the river, seek medical or veterinary advice.

We will continue to share updates about the designated bathing site as further information becomes available from the Environment Agency's monitoring and sampling programme.

The Environment Agency advises the public to report environmental problems through GOV.UK, including fish in distress and algae blooms in other sections of the river, or call 0800 80 70 60.