The Environment Agency will find out tomorrow (Tuesday 12 October) if Britain’s most iconic river has been crowned the beauty queen of the planet’s waterways and scooped the world’s largest environmental prize.

The River Thames has been shortlisted out of hundreds of rivers across every continent as a finalist in the International Theiss River Prize, which celebrates outstanding achievement in river management and restoration.

London’s renowned waterway is up against the world-famous Yellow River, in China, Hattah Lakes, Australia, and the Smirnykh Rivers Partnership, in Japan.

The Thames has made the final four thanks to its dramatic recovery from a biologically dead river in the 1950’s to today’s thriving waterway; teeming with fish, and with returning salmon, otter and sea trout populations.

The chemical quality of the rivers within the Thames catchment classed as ‘Very Good’ or ‘Good’, has improved from 53% in 1990 to 80% in 2008 while the estuary supports viable shellfisheries and is a nursery ground for commercial sole and bass stocks. The numbers of fish are increasing, with 125 different species recorded, including internationally important smelt and shad.

Since April 2005, 393 habitat enhancement projects have been completed and nearly 70 km of river has been restored or enhanced.

Alastair Driver, the Environment Agency’s National Conservation Manager, said: “In the last 150 years the Thames has been to hell and back, and it has taken thousands of people many decades to restore it to this point. Tighter regulation of polluting industries and our work with farmers, businesses and water companies to reduce pollution and improve water quality, have all helped to make the Thames a living river once again.

“But the recovery is fragile, and under increasing pressure from a growing population, ageing infrastructure and climate change. Through innovative projects such as the Thames Tideway tunnels and the London Rivers Action Plan, we and all of the people and organisations we work with are proving that we are tackling these challenges head on to ensure that the Thames remains an iconic river for many centuries to come.” The Environment Agency has pledged that if it wins, the $350,000 AUD (Australian Dollars) prize money will go to the Thames Rivers Restoration Trust. Part of the prize fund will be used by the Trust to establish a twinning project to help restore a river in the developing world.

Boris Johnson, Mayor of London, said: “The Thames is one of our most precious assets, so I am thrilled to see that efforts to improve and preserve its good health are being lauded on the world stage. Congratulations to all those who have played a part in this success.”

The actor David Suchet, a keen boater and chairman of the River Thames Alliance said: “I am fortunate in my life to have travelled extensively and enjoyed many other rivers worldwide. But the River Thames is priceless and one of the most glittering jewels in the crown our English heritage.”

Sally Chatterjee, CEO, Visit London commented on the shortlist, “The River Thames is a huge part of tourism in the capital. Not only do the banks of the Thames offer great walks, attractions and places to eat and drink but the river itself is a popular alternative for travelling across the city. For visitors, leisure cruises offer wonderful and unique views of some London’s most iconic landmarks.”

Chris Poupard, Chair of the Thames Rivers Restoration Trust, said: “We are delighted to have helped the Thames reach the finals of the International River Prize. This is a recognition of all of the hard work and investment by many people and organisations over the past 50 years. We will continue to play our part in delivering the plans that are in place to make the river even better in future.”

The award will be presented tomorrow (October 12) at the International Riversymposium in Perth, Australia.