Conservationists celebrate revival of the River Thames – and call for more action

(by Karma Loveday)

The latest State of the River Thames report by conservation charity the Zoological Society of London (ZSL) has set out how decades of dedicated action have revived the capital’s river for people and nature – including harbour porpoises and wading birds.

The report, an update to the first The State of the Thames published in 2021, used 21 different indicators to assess the health of the river. The improvements reported included:

• Lower concentrations of toxic metals – zinc concentrations were half and copper concentrations a quarter of those present in 1990.

• More ‘breathable’ water for the river’s underwater wildlife – phosphorous levels have decreased, an achievement attributed in part to Thames Water’s upgrade of five London sewage treatment works and investment in the Lee Tunnel. ZSL looked forward to further gains from the Thames Tideway Tunnel. This is expected to capture 95% of sewage currently entering the tidal Thames, and since autumn 2024 has already captured 13m tonnes. 

• Plastic cotton bud sticks, once one of the most commonly found litter items in the Thames, have all but disappeared from its shores following the UK’s sale-ban in 2022. ZSL hopes the same will be achieved for plastic wet wipes, which are due to be banned later this year. 

• New riverside walkways and nature habitats along the banks of the waterway. 

While celebrating these achievements, the report called for more action to tackle issues that threaten the River Thames’ resurrection. These included: 

• Higher water temperatures – the summer temperature has increased on average by 0.13⁰C each year since 2007, equivalent to a 1⁰ C temperature rise every eight years.

• Rising water levels – water levels by Tower Bridge and the Tower of London, for instance, have been rising by 5mm each year on average since 1993. This also increases the risk of upstream waters becoming more saline, potentially leading to the loss of rare freshwater tidal habitat along the Thames and the interwoven communities of wildlife that it supports.

• Pollution – from sources as diverse as forever chemicals, road run-off, sewage and pharmaceuticals. Nitrate levels have steadily increased over the last 35 years, which risks further unbalancing the delicate ecosystem.

Alison Debney, ZSL lead for UK nature recovery, said: “As we enter a new year, the Thames reminds us that transformation is possible. The Thames may have been declared ‘biologically dead’ in the 1950s, but the estuary we see today demonstrates just how quickly things can change when decisive action is taken. We’re celebrating those wins today – but we must act now to secure the wins of tomorrow.”