Blue-green algae blooms have appeared at Richmond Lock and between Sunbury Lock and Teddington Lock, prompting an immediate Thames algae warning Richmond residents need to follow. The council is urging you to avoid all contact with the water until further notice, which affects your usual swimming spots, riverside walks with dogs, and plans to use the designated bathing site near Teddington. This is the first time this summer that algae has reached the Richmond Lock section of the river.
The blooms produce toxins harmful to humans and animals, particularly dangerous for dogs who may drink the water.
Where the algae has been found
Two distinct locations are affected
The Environment Agency has confirmed blue-green algae at Richmond Lock and in a separate bloom stretching between Sunbury Lock and Teddington Lock. The Teddington site sits close to the designated Thames bathing area, which has been in use throughout the summer. Both blooms are visible on the water surface, typically appearing as green or blue-green scum, sometimes with a paint-like sheen.
If you walk the towpath between these points, you will see the affected areas clearly marked.
What you should do now
Avoid all contact with the water and visible algae
Do not swim, paddle or bathe anywhere between Sunbury Lock and Richmond Lock until the council confirms the blooms have cleared. Keep your dogs on leads near the water and prevent them from drinking or entering the Thames. If your dog does make contact, rinse them thoroughly with clean water immediately and contact your vet if they show signs of illness such as vomiting, diarrhoea, or seizures. Children should stay well back from the water’s edge at all affected sites.
Your usual river activities will resume once testing confirms the water is safe again.
What this means for you
Check the council’s website and social media channels daily for updates on when the algae warning is lifted. If you have river swimming or boating plans for the next fortnight, make alternative arrangements now. Dog walkers should use inland routes through Richmond Park or Bushy Park instead of the towpath between Sunbury and Richmond Lock. The borough will post notices at access points along the affected stretch, but treat any visible algae with caution regardless of signage.
The algae blooms are a natural occurrence during warm weather and typically clear within days to weeks. Your safest course is to stay informed through official channels and keep clear of the water until you see confirmation that testing has come back clean.
Two separate bloom sites within the borough means a significant stretch of your local Thames is now off-limits, from Sunbury through to Richmond itself.
Frequently asked questions
How do I recognise blue-green algae?
- Blue-green algae typically appears as green, blue-green or greenish-brown scum on the water surface. It often looks like paint or pea soup floating on the water, sometimes with a musty or grassy smell. If you see anything matching this description, stay away and keep pets away.
How long will the algae warning last?
- The duration depends on weather conditions and water temperature. Algae blooms usually clear within days to a few weeks. The council will continue testing and will announce when it is safe to resume water contact. Check their website daily for updates.
What happens if my dog drinks Thames water with algae?
- Blue-green algae toxins can cause rapid illness in dogs, including vomiting, diarrhoea, seizures, breathing difficulties, and in severe cases, liver damage or death. Rinse your dog immediately with clean water if they have contact, and call your vet straight away if any symptoms appear.
Can I still walk along the towpath?
- Yes, you can walk the towpath safely as long as you and your dog avoid contact with the water. Keep dogs on leads and bring fresh drinking water for them. The risk comes from ingesting or touching the algae, not from walking near the river.
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