The UK government recently gave the go-ahead for Thames Water, the country’s biggest water company, to build the Tideway Tunnel: 32-kilometre-long sewer costing £2 billion (around US$3.96 billion), which will run from west to east, 80 metres underneath the capital’s streets.
London's sewers carry both rainwater and untreated sewage, and present limited capacity means that when heavy rains overwhelm the system, the overflow discharges into the River Thames. In increasing the sewage-treatment capacity, the new tunnel is designed to reduce the amount of untreated sewage that ends up in the river.
London's sewers were built in the second half of the nineteenth century, and are regarded as one of Britain's major engineering successes. But the growth of the city and worsening droughts mean that the system is now overloaded; every year up to 32 million cubic metres of sewage and rainwater discharge into the River Thames and Lee from sewage network overflows.
Experts describe London's sewers as one of the main threats to the health of the Thames. If this cannot be changed, efforts to control pollution in the river will be wasted.
The new tunnel – an unprecedented project – is due to be completed by 2020 and will improve the water quality of the River Thames, hopefully restoring London's pride in the world's busiest river.
Untreated sewage in the river is killing fish and harming the tourist industry, according to the UK department of the environment.
The most serious incident occurred in 2004, when a series of downpours overwhelmed the system, causing localised flooding and a large overflow of polluted water into the Thames, killing off large numbers of fish and threatening a recovering ecosystem.
According to reports, 52 million cubic metres of untreated sewage and rainwater pollute the Thames and Lee every year. But perhaps to the surprise of Londoners, 129 species of fish and 250 invertebrates still survive in the Thames, and the river is cleaner and healthier than it has been for two centuries.
In fact, the Thames is acknowledged to be one of the world's cleanest urban rivers. But like many of China's rivers today, at one time urban and industrial growth threatened its ecosystem – almost to the point of collapse.
photo by apuls
In the nineteenth century, the River Thames went into decline. In 1800, records show that London's fish markets still sold 3,000 salmon caught in the River Thames. But in 1805, the capital's population reached one million. And as the city grew, more waste from London's cesspits – and from newly-designed flushing toilets – flowed into the river. The river started to stink – and to die.
Greater industrialisation also saw slaughterhouses and tanneries built alongside the river, polluting the river even further. There were repeated cholera outbreaks, the worst of these in 1849, which killed thousands of people.
Only when cholera was identified as a water-borne disease – and the River Thames as an important source of the outbreaks – did the UK's efforts to clean up the river begin in earnest, helped in large part by public reactions to the “Great Stink” of 1858. The new sewer system was finished in 1874, and is still in use today.
To safeguard the water supply, London also started to monitor the quality of the river’s water, and improve sewage treatment – greatly improving the quality of the city's drinking water supply.
The UK privatised the water industry at the end of the 1980s, and London’s water supply and treatment was taken on by Thames Water.
photo by Bobcatnorth
The company made massive investments in services and infrastructure, spending US$400 million on the Thames Water Ring Main in 1994 – the city's largest tunneling project since the London Underground.
Thames Water is investing £3.1 billion (US$6.15 billion) in renewing and developing infrastructure from 2005 to 2010, including an expansion of the Thames Water Ring Main, due to be completed by 2010.
It has also invested U$500 million in the UK Advanced Water Treatment Program, bringing ozone and active carbon water treatment methods to its UK plants in 1997.
There are 845 waste management sites within the Thames basin. These, along with the closure of harbours and the removal of heavy industry have made the Thames one of the world's cleanest urban rivers.
However, the Thames Explorer Trust – an educational charity – points out that the river environment is threatened by overcrowding, and pollution from traffic and industry. Building on the river’s shallows, banks and flood plains and rubbish tipping also threaten the river. Moreover, statistics reveal that 946 million litres a day are still lost through leaks from London’s aging water infrastructure.
The Thames region covers 13,000 square kilometres – only 10% of the total land area of England and Wales. However, it is home to one quarter of the population, and accounts for over one quarter of the UK's gross national product. It also covers 896 square kilometres of flood plains, one of the UK's most important wildlife habitats.
Lessons for China
China’s rapid industrialisation has seen many rivers repeat the same tragedy that happened to the Thames in the nineteenth century. In the 1830s, salmon disappeared from the Thames, not to return until the 1970s.
The 2006 Yangtze Freshwater Dolphin Expedition failed to find a single trace of the baiji; it is almost certain the “goddess of the Yangtze River” is now extinct. Numbers of the finless porpoise, a species unique to China, are also plummeting, and it may soon follow in the baiji's wake.
Industrial and domestic waste is killing the Yangtze River. Half of China's petrochemical companies are located in the Yangtze River basin. The area has only 280 water treatment plants, and only 30% of sewage is treated.
The WWF recently identified the Yangtze River as one of the world's 10 most endangered rivers, warning of the dangers posed by dams, shipping, pollution and climate change.
The situation across China is no better. Seventy percent of rivers are polluted to varying degrees, as is 90% of urban groundwater.
Government figures show that although water treatment rates in relatively developed cities reach 80%. Beijing achieved 90% in 2006, but half of the nation's 600 cities do not have a single water treatment plant.
As of the end of last year, the national rate of urban sewage treatment was 56%, four percentage points higher than the previous year. China aims to raise this figure to 70% by 2010.
Pan Yue, deputy director of China’s State Environmental Protection Agency (SEPA), has said that since the 2005 pollution accident in the Songhua River, there has been a water-related pollution incident every two to three days on average.
China is currently facing a water shortage crisis, made worse by water pollution. Does the country have a century to solve these problems? Without any doubt, we do not.
Dongying Wang is the managing editor of chinadialogue.
Homepage photo by wallyg