Blue-Green Algae – Important Information for River Users

Blue-Green Algae in the River Thames at Richmond and Teddington – Important Information for Richmond Canoe Club Members

The Port of London Authority (PLA) has issued Notice to Mariners U31-26, confirming elevated levels of blue-green algae in the River Thames between Teddington Lock and Richmond Lock. This includes the stretch of river around Richmond Half Lock, Richmond Lock and Teddington Lock.

The notice is available on the PLA website: Notice to Mariners U31-26

The River Thames has not been closed to paddling. However, blue-green algae can produce toxins which may be harmful if contaminated water is swallowed or comes into significant contact with the skin.

Richmond Canoe Club has introduced some temporary precautions and prepared two documents for members:

Risk Assessment _ Date_ 26 August 2026 _ Blue-Green Algae – Interim Risk Assessment and Op.

Download • 544KB

Coach Guidance _ 26 August 2026 _ Blue-Green Algae – Interim Risk Assessment and Operating.

Download • 154KB

Please read the risk assessment. The second document is mainly for coaches, but it is also useful for members because it explains how organised paddling sessions on the River Thames at Richmond and Teddington will be managed.

For now, members should:

• Avoid visibly affected water, surface scum or floating green material.

• Avoid deliberate swimming, capsize practice or unnecessary immersion in the River Thames, particularly between Richmond Half Lock, Richmond Lock and Teddington Lock.

• Avoid swallowing river water and minimise unnecessary splashing.

• Wash your hands after paddling and shower after significant contact with river water.

• Follow any instructions given by coaches or session leaders.

Experienced paddlers can continue to paddle as long as they follow these precautions. We are taking a more cautious approach with junior beginners and activities where falling into the water is reasonably foreseeable.

The Club is actively monitoring the River Thames around Richmond and Teddington. If you see what you think may be blue-green algae, please take a photograph if possible and email the original photograph to safety@richmondcanoe.club, together with the approximate time and location.

Original photographs may contain GPS or geolocation information, which helps us identify and map exactly where observations are being made. Please do not edit or compress the photograph before sending it.

Please do not rely on appearance alone. Water that looks clear does not necessarily mean that blue-green algae or toxins are absent.

The Club is keeping a close eye on advice from the Port of London Authority and the Environment Agency, including the information in PLA Notice to Mariners U31-26. We will review the situation as conditions change and let members know if further precautions are needed or the current warning is withdrawn.

Issued on behalf of the Richmond Canoe Club Committee – 26 August 2026