Public Information Notice: Blue-Green Algae Bloom in the River Thames

Public Information Notice: Blue-Green Algae Bloom in the River Thames

Dear Residents,

Please be advised that the Environment Agency has identified a blue-green algae bloom in the River Thames, which was first detected on 18 August 2026.The bloom continues to persist along a 10-kilometre stretch of the lower River Thames, between Sunbury Lock and Teddington Lock, including the Ham and Kingston Designated Bathing Water area.

This has been classified as a Category 1 environmental incident due to the potential risks it poses to:

There have been unconfirmed sightings of small, isolated patches of algae within the tidal Thames between Teddington Lock and

Richmond Half Tide Lock (approximately 5 kilometres). While conditions in the tidal Thames are generally less favourable for this type of algae due to salinity, turbidity, and tidal water movement, there remains a possibility that patches could spread with tidal activity.

As a precaution, members of the public are advised to exercise increased caution in the upper tidal Thames. We strongly advise the public to:

We have advised the public to report environmental incidents on GOV.UK, 0800 80 70 60, such as fish in distress or algae blooms in other reaches. 

At present, it is not possible to predict how long the algae bloom will persist. However, cooler weather conditions and increased river flows are expected to help improve the situation over time.

Thank you for your cooperation and support. Further updates will be provided as the situation develops.

Please also visit the links below for more information,

Teddington Safer Neighbourhood Team

Inspector Jon McLoughlin

Sergeant Philip Ross Martyn

PC Amanda Stonehouse

PCSO Saini Sukhbinder

PCSO Kitiya Silawan