The River Thames is entering 2026 with renewed vitality, according to the latest health assessment by the Zoological Society of London (ZSL). Once declared ‘biologically dead’ in parts of the 1950s, the famous river has undergone a striking recovery thanks to decades of sustained environmental action. The updated State of the Thames report reveals significant improvements in water quality and wildlife habitats, benefitting both nature and the millions of people who live along its banks.
The report highlights reductions in toxic metals such as copper and zinc to levels below those harmful to aquatic life, and improvements in dissolved oxygen – making the water more supportive of underwater species. Initiatives such as new riverside green spaces and restored natural habitats have enhanced the river’s appeal for wildlife and recreation alike.
Notably, plastic cotton bud sticks, once among the most common litter items, have almost vanished following the UK’s 2022 sales ban, and hopes now rest on an upcoming ban on plastic wet wipes to yield similar results.
Despite these gains, experts warn that threats remain. Climate change is raising summer water temperatures and sea levels, challenging the river’s fragile ecosystem, while pollutants including road run-off, sewage and pharmaceuticals continue to pose risks. The river’s role in providing drinking water, supporting food and livelihoods, and offering flood protection underscores the urgency of coordinated action across government, industry and communities.
Marking the start of ZSL’s 200th anniversary, the report draws on data from 21 indicators and collaborators to chart progress and pinpoint areas needing attention. Investments such as the Thames Tideway Tunnel and sewage treatment upgrades have captured millions of tonnes of untreated sewage, further improving water quality. The message is clear: the Thames’ resurgence shows what determined conservation can achieve, but continued effort is essential to secure its future
