The clean up of the River Thames

Standing statue still on the shoreline, the heron is almost impossible to spot against the reeds behind it. Only once our boat draws near does the bird stir, flapping its broad, grey wings to lift itself into the air.

Other smaller birds dart across the skyline before settling in the water while there is the occasional plop as a fish breaks the surface. It is an idyllic riverside scene that is found in many places through out the English countryside. The difference on this occasion is this stretch of river sits in the midst of the country’s biggest city. We are on the lower reaches River Thames, in the middle of a large industrial estate at Creekmouth, in Barking, London.

It was near this spot in 1878 that more than 600 passengers on the steamship Princess Alice died when the pleasure boat sank in a collision. As they swam towards the safety of the shore, the passengers were overcome by the noxious cocktail of pollution in the water. In 1957, the pollution levels became so bad that the River Thames was declared biologically dead. The amount of oxygen in the water fell so low that no life could survive and the mud reeked of rotten eggs.

Fifty years later, the Thames has become a very different place. It teems with life: 125 species of fish swim beneath its surface while more than 400 species of invertebrates live in the mud, water and river banks. Waterfowl, waders and sea birds feed off the rich pickings in the water while seals, dolphins and even otters are regularly spotted between the river banks where it meanders through London.

The transformation has won the International Theiss River Prize, a £220,000 award given to rivers that have undergone outstanding restoration, will be picked from a short list of four rivers: The Thames, the Yellow River, in China, Hattah Lakes in Australia and the Smirnykh River in Japan.

Environmental officials now say the Thames is the cleanest it has been in more than 150 years and nearly 400 habitats have now been created to allow wildlife back into the river.

Back in Barking, the evidence of this recolonisation of the Thames is all around. The water itself still looks murky - due to the large quantities of silt and mud the water carries downstream - but it now supports a huge diversity of fish. Juvenile Sea bass, until recently never seen before in the Thames, now fill the creeks that feed into the Thames while flounder, a flat fish, have returned in ever growing numbers. Adult salmon have even been reported migrating up the river.

Above the water too, there are signs of how life has taken hold again.

Crouched among the reeds beneath Barking Barrier is Dennis Ellisdon, a 72-year-old retired marine surveyor and avid birdwatcher. He has been coming to the area, a short drive from his home in Bredbury Station, for 11 years and has spent the morning searching for a pair of peregrine falcons that have been reported nesting in the area.

“You often get kingfishers and a lot of wader birds when the tide is out,” he said. “There are also a lot of migrating birds that stop here now like red starts - that was a big surprise.”

“I seldom go out without getting a bit of a surprise. You can hear the clank of metal from the scrap yards nearby and the planes at City Airport, so it is not necessarily a haven of peace and quiet, but it is definitely a wildlife haven.”

Rare species of wildlife are also making surprise appearances. Water voles are critically endangered across much of the country, but at Thamesmead, just a mile upstream from Barking, the tiny aquatic creatures are thriving. Regular flashes of blue and green can also be seen on many stretches of the river, such as by Dartford Creek, revealing the presence of kingfishers in surprising numbers.

Otters have also set up home in several areas along the river while seals, more normally seen on the coastline than in rivers, are regularly spotted hauled out onto the banks after a good meal. Dolphins also often swim up the river.

Even one of the most fragile and rare sea creatures, the sea horse, have been found in the saline waters of the Thames Esturary.

David Curnick, marine and freshwater programme co-ordinator for the Zoological Society of London, said: “We have had reports of 4 short snouted seahorses over 4.5 years. The Thames has obviously undergone a tremendous transformation since the 1950’s. It is feasible that there a significantly greater populations than our results suggest.”

Much of the return of wildlife to the Thames has been due to improvements in water quality. Strict legislation now prevents industry from dumping polluted effluent into the river and its tributeries. Sewage from London and the surrounding area is now treated and then exported.

“Improving the water quality is only half of the battle though,” explains Antonia Scarr, a senior marine advisor with the Environment Agency. “We have had to create the habitats to allow the plants, fish and wildlife to move into.

“If you look along a lot of the River Thames as it passes through London, it is lined with concrete and pilings. Water can’t get into these and so there is no way plants can get a foothold.”

The Environment Agency, along with local authorities along the Thames, have now set about removing many of these old concrete barriers that contained the rivers. Instead they have been bulding up mud banks and allowing reed beds to take hold. Piles of rubble at the side help to capture sediment that provides a rich habitat for invetebrates and moluscs that are food for many other species. In areas where they have been unable to remove the barriers completely, they have tried putting sediment behind wooden panels along the walls.

“This essentially turns what would have been a horizontal mud bank on the river floor into a vertical one,” said Mrs Scarr. “When we have sampled them, we have found they are full of invertebrates.

“The fact that we have species like otters on the Thames shows we are getting rid of the pollution and creating the right kind of habitats for them.”

Even on the smaller rivers and streams that feed into the Thames there is a transformation underway. In Greenwich and Lewisham, extensive work is underway to re-naturalise rivers that for decades have passed unnoticed beneath residents feet. During the 1960s and 1970s extensive work was undertaken to help prevent rivers from flooding into the surrounding neighbourhoods and many were simply diverted into underground tunnels.

The river Quaggy in Greenwich is one such example. In an area called Sutcliffe Park, the river passed though a culvert hidden beneath a large flat area that was used for football pitches. But in an attempt to restore the wildlife and rich biodiversity that once lived on the river, the Environment Agency opened up the culvert allowed the river to meander through the park. It is now lined with bull rushes and reeds while dragonflies and damsel flies dart between the huge number of plants that have established themselves there. Frogs, geese, grebes and other water fowl also flourish on the site. The park also provides space for the water to spread out into when it does flood, so it doesn’t flood the houses downstream.

Dave Webb, biodiversity team leader at the Environment Agency who helped lead the project, said: “The idea in the past was to get water as fast as possible from A to B so these smooth concrete channels were created. Sadly, they are completely barren when it comes to life as nothing can get a grip there.

“In Sutcliffe park we now have huge diversity of life and it is providing a corridor to allow species to move up and down stream to places they couldn’t get to because of the old culvert that was here before.”

But for people like Dennis Ellisdon, the simple pleasure of having a river that supports the kind of wildlife he loves to watch is enough.

“The sheer variety of birds you can see here now is what amazes me. You would never have seen a heron here before as there wasn’t the fish to support them. Now the river seems to be doing well.”