Help boost River Thames Conservation

I have now been ZSL's CEO for two years. There are some days I have to put on a suit and occasionally even a tie, to meet Ministers and other VIPs. Other days I’m in waders, trudging down rivers, or in wellies mucking out the rhinos. 

Whatever I’m wearing and whatever I’m doing, it is always in pursuit of ZSL’s mission to protect nature. We work around the world, but some of our most important work is in London itself, on the Thames and its tributaries. Sadly, the UK's rivers are in dire condition. But there is hope -  we know that when it's done right, conservation works.  And the Thames has been brought back to life, having been declared biologically dead.

This is a massive team effort. Last month, ZSL joined other partners in showing our support for Sadiq Khan’s 10-year plan to clean up the Thames. As part of his plan, the Mayor aims to reduce sewage discharge in the tidal Thames by around 95%. The Mayor wants to use nature as the solution as well as the beneficiary, wherever he can.   

This sort of ambition is essential. The actions of humanity are damaging nature and changing the climate at a terrifying rate. We need serious ambition to tackle both biodiversity loss and climate change, and to tackle them together.

Our State of the Thames Report assessed the health of the capital's waterway. It revealed that climate change is even impacting the Thames' temperature—on average, raising the river by 0.2⁰C per year and posing huge challenges for its wildlife. So ZSL, the Mayor of London and all our partners have our work cut out for us. 

Outfall Safaris 

Much of Greater London is serviced by two separate drainage systems. One collects rainwater and flows directly into our rivers; the other takes foul wastewater from buildings to sewage treatment works to be cleaned before being released into a river. Misconnections between the two drainage systems, often caused by inexpert plumbing, result in pollution pouring directly into our rivers via drains known as outfalls. 

Until recently, outfalls in urban rivers were not systematically surveyed to identify pollution and notify the relevant authorities. 

That’s where the Outfall Safari Project comes in. It was developed by ZSL in 2016 in partnership with Thames Water, the Environment Agency, NGOs, and local communities in Greater London. Citizen science volunteers gather evidence and report it using an app sent to Thames Water so action can be taken. 

Want to join me in waders? 

Become a volunteer to learn how to identify outfalls, rank the extent of pollution, and report severely polluting outfalls via an app during one of our Outfall Safari Expeditions. 

The results of all surveys are then sent to Thames Water, which uses the data to identify the sources of pollution from the outfalls and prevent further pollution from entering the rivers.

Seal Monitoring 

Since 2013, we’ve had a project monitoring grey and harbour seals in the area. For the first time this year, we were supported by RAF. Why is this so important?  As keystone species and top predators in the Thames, seals play a crucial role in maintaining biodiversity within their ecosystem. Any changes in their populations may indicate significant problems caused by industry or climate change that need urgent action. 

Become a seal spotter supporting the ‘Thames Seals Unit’

Without disturbing the seals, we’re asking the public to support ongoing work in understanding and protecting seals and other mammals living in the Greater Thames Estuary by reporting live sightings to the Thames Marine Mammal Survey.

Sadly, death is a part of life, but it is important information for conservation work. You can report dead sightings to the ZSL-led Cetacean Strandings Investigation Programme, which investigates stranded whales, seals, marine turtles, and sharks in England and Wales. 

Eel Conservation 

It's not just the big mammals that are getting our attention. European eels once thrived in London’s rivers, but we have made it harder and harder for them , so much so that the species is now classified as ‘Critically Endangered’ by the IUCN Red List of Threatened Species. 
Our work on European eels started in 2005 and now ranges from informing international conservation policy and leading UK research on eel behaviour to practical conservation in the Thames Catchment. 

Until 2022, no one was sure where European eels came from. Our scientists cracked the case by catching adult eels in the Azores and fitting them with satellite tags. We were able to watch the eels return to their mysterious breeding grounds in the Sargasso Sea.

Monitor the mysterious European eels

You’d get hands-on help to secure a future for a Critically Endangered species. How many people can say that?

You can help measure and count the eels as they migrate through our rivers to better understand their life history and distribution. This is part of our work with partners in the Thames Rivers Trust Thames Catchment Community Eels Project to co-develop a standardised methodology for citizen science river walkover surveys with the aim of mapping barriers and assessing their impact on upstream eel migration.

Transforming the Tidal Thames Estuary

Where the river joins the English Channel, the Greater Thames Estuary is one of Europe's most important wildlife sites. This coastal wildness is home to important birds, rare invertebrates, and essential fish habitats. The seagrass and salt marshes are some of the most effective habitats for capturing and storing carbon in the world.

ZSL partnered with 17 organisations to unify these fragmented habitats and restore the entire coastal habitat to its former glory. A diverse mixture of thriving habitats, particularly for native oysters, intertidal seagrass, salt marsh, coastal grazing marsh, saline lagoons sand and shingle bird nesting. 

While significant conservation work already exists, the Partnership's systematic and coordinated approach promises to enhance the entire estuary system. By March 2025, our habitat restoration plan will be completed, and the first five years of work can start!