Years of commitment have led to the River Thames experiencing a revitalization, according to a new report from the London Zoological Society (ZSL).
In the 1950s, the river was officially deemed “biologically dead,” a result of industrial waste being dumped into its waters, including chemicals, heavy metals, oils, and dyes.
Since then, concerted efforts and favorable policies have facilitated the re-emergence of treasured species like harbour porpoises and wading birds.
Nonetheless, experts caution that this hard-won recovery faces risks from climate change and ongoing pollution.
The latest State of the River Thames health assessment aggregated the most current data from 21 indicators used to evaluate the river’s health.
It revealed reduced levels of toxic metals, improved water quality for aquatic creatures, and the establishment of new habitats along the riverbanks.
The report also highlights how swiftly regulations can yield positive outcomes. Following the UK’s ban on the sale of plastic cotton bud sticks in 2022, these items, once prevalent in Thames litter, have nearly vanished from its banks.
Conservationists at ZSL are hopeful for similar results regarding plastic wet wipes, another significant pollutant found in the Thames, which are set to be banned later this year.
Additional achievements for public health and environmental improvements include reduced levels of harmful copper and zinc in the river, lowering to safe thresholds that protect the aquatic ecosystem.
Zinc levels saw a drop of 50% in 2024 compared to 1990 figures, with copper levels reduced to just one-quarter of their previous concentration.
Alison Debney, ZSL’s UK nature recovery lead, remarked: “As we embark on a new year, the Thames serves as a reminder that change is achievable.
“Although it was termed biologically dead in the 1950s, the estuary observed today exemplifies how swiftly progress can occur when resolute measures are implemented.
“We celebrate these victories now, yet we must take immediate action to ensure future successes.”
Despite this progress, the report indicates that increasing temperatures and sea levels, along with regional challenges like road runoff, sewage, and pharmaceuticals, threaten the estuary’s long-term viability.
Since 2007, summer temperatures in London’s waterway have risen by an average of 0.13°C each year, leading to a cumulative increase of 1°C every eight years.
In the city’s core, water levels near Tower Bridge and the Tower of London have been rising by an average of 5 mm each year since 1993.
As water levels continue to escalate, there is a heightened risk of upstream waters becoming saltier, jeopardizing rare freshwater tidal habitats and their corresponding wildlife communities along the Thames.
Additionally, harmful concentrations of nitrates have gradually increased in the Thames and two of its monitored tributaries, the Rivers Lee and Darent, which poses a further threat to the ecosystem’s balance.
To maintain the river’s health, the conservation charity initiated the Transforming the Thames project last year, uniting conservationists, communities, government agencies, and landowners to enhance recovery efforts throughout the Greater Thames Estuary.
Their initiatives include creating oyster reefs, planting seagrass meadows, and restoring saltmarshes, which are vital nesting sites for local bird populations.
Charlie Wood, the London area director at the Environment Agency, stated: “This ZSL report is an excellent illustration of the health of the River Thames, and we are thrilled to have participated.
“Through such monitoring and data collection, we can gauge the improvements made in restoring the river to its vibrant state while also pinpointing emerging threats, such as those posed by climate change.
“Stringent regulations and targeted investment in infrastructure have been pivotal in achieving these advancements, but the future of the Thames also depends on our ability to collaborate across public, private, and voluntary sectors, and we look forward to continuing this partnership.”
