What is the tidal Thames?

London is a coastal city – its tidal river hosts seals, seahorses and porpoises 

Twice a day the Thames undergoes an incredible transformation – from a slow-moving river to a brimming marine environment as the North Sea floods inland. This remarkable event – governed by the moon – changes river height by up to 7m in just six hours.  This 95 mile stretch from Teddington to Southend influenced by the ocean tides is the tidal Thames.

As the sea water recedes it reveals a vast and beautiful riverbed that makes up London’s largest natural space.

This is a place for everyone to enjoy

See Thames Estuary Partnership’s wonderful virtual journey for more info.

Water quality has dramatically improved since the river was declared biologically dead in 1957…

It’s now full of wildlife thanks to improvements in sewage and industrial waste treatment. Over 120 species of fish have been recorded in the river since the 1950s and marine mammals such as seals and porpoises have made a remarkable recovery.

Yet insufficient sewage infrastructure threatens the river once again…

Sewage is a huge issue in the river. Even a light drizzle of rain causes untreated sewage to spill into the River Thames from London’s Victorian sewer network. This adds up to tens of millions of tonnes of sewage entering the tidal Thames every year.

The Thames Tideway Tunnel will deal with around 95% of the sewage discharged in central London between Hammersmith & Greenwich. However, unacceptable discharges of raw sewage into the Thames will continue upstream of Hammersmith.

Further investments in sewerage infrastructure are needed urgently from water companies to address sewage in the Thames.

The land where London sits was once covered in saltmarsh and wetland…

These are great places for small fish to stay out of the main river and away from predators.  As the city has grown, buildings and flood defences have removed this crucial habitat.  The little pockets that survive, such as that the reedbeds below at Barking Creek, are invaluable habitat for wildlife and should be treasured.