VIVID pictures of the sea around Qingdao, the Olympic sailing venue, covered in a thick blanket of bright green algae have sparked inevitable jokes about just what China meant when it promised a "Green Olympics".
The formidable resources of the Chinese Government, which has spent billions of dollars to improve Beijing's air quality and environment in time for the Games that open a month from today, may provide a month-long, picture-perfect Beijing, lush with lakes and sparkling fountains.
But to a considerable extent, this will be a mirage, cloaking an environmental disaster in which the capital could cease to exist within a generation because of a chronic lack of water, Chinese experts have warned.
Officials said the Qingdao algal bloom was a natural disaster caused by unusually hot and humid weather. But it is more likely it was caused by the discharge of untreated sewage, run-off from fertiliser and industrial pollution.
The incident highlights the enormous challenge China faces in rectifying the damage caused by 30 years of rapid industrialisation in which economic growth was promoted at any cost.
The Olympics have been a catalyst for action and at times an uncomfortable spotlight on the efforts of Chinese authorities to improve environmental quality to meet their goal of holding a Green Olympics.
Last week three of Beijing's environment chiefs gave a glowing report on the capital's planting of 22 million trees and the reforestation of its once-bare mountains. The deputy director of the Beijing Water Authority, Bi Xiaogang, said Beijing would not experience algae problems similar to those at Qingdao because the city had worked hard to reduce pollution and had increased treated sewage rates.
But a visit to the Wenyu showed how difficult the challenge was. The city's last running river was covered
Though it was nothing like the wet-wool algae at Qingdao, the discovery is surprising - particularly since Bi had proudly announced that Wenyu's water quality had been upgraded from category five or too polluted for any human use, to category four, which is suitable for industrial use and "entertainment without direct touch of human skin".
At the riverside, a shepherd, Mr Sun, 45, and his wife and son, were trying to force their herd of dirty, heat-affected sheep into the algae-covered water for a wash.
Weeks of hot and humid weather had made them lose their appetite and he hoped a bath, even in dirty water, would improve things. But the sheep refused to go into the dirty river.
Asked about water quality, Sun shrugged. It is worse farther up because a factory discharged into the water, he said.
The family said it had seen small improvements in water quality this year. The birds had returned but the fish were small, smelt bad and could not be eaten.
Last year the Beijing Municipal Government spent $US57 million ($59.6 milllion) to build a 13 kilometre pipeline to divert water from the Wenyu River to the dried-up Chaobai River bed next to the Olympic Shunyi Canoe and Rowing Park.
The Chaobai dried up nine years ago through over-exploitation, as even the official Xinhua newsagency acknowledged. The diversion project will provide 38 million cubic metres of water to the Chaobai to improve the environment and scenery around the venue during the Olympics.
The 1.7 billion cubic metres of water needed to fill the parks and competition waterways will be drinking water, taken from the Miyuan reservoir, Beijing's main drinking water source. The venue will also need to replenish a third of its water capacity each year - almost 600,000 cubic metres - even after all the rainwater-gathering systems and water recycling and treatment projects at the park are operational.
Beijing's thirst for an estimated 200 million cubic metres of water during the Olympics has also meant the construction of a 17 billion yuan ($2.6 billion), 309 kilometre canal to pump water from neighbouring drought-stricken Hebei to Beijing in time for the Olympics. The canal is part of the Yuan500 billion south-north water diversion project that involves building three canals to channel water from the Yangtze River in the south to the parched north.
At the Green Olympics briefing last week, the Beijing Water Authority's Bi said the canal would be used only for emergencies. He conceded the city's heavy reliance on shrinking groundwater reserves was not ideal: three-quarters of Beijing's water now comes from underground wells up to 1000 metres deep.
But he hoped that if the heavier-than-average rains Beijing had had this year - 40 per cent more than last year - continued, the city would have adequate supplies to meet the needs of an extra 2.5 million Games visitors without resorting to piping in water from Heibei.
His remarks were in response to questions about a recent report by a Canadian group, Probe International, which accused the city of using already strained underground supplies to provide water for Olympic beautification projects such as a huge music fountain that is so costly to run it is likely to be turned on only during the Games.
"Within a generation, this city would cease to exist," said Dai Qing, China's best-known environmentalist who helped write the report. "We won't have the ancient capital any longer and the ugly modern Beijing would disappear too. Unfortunately, Government officials and Beijing residents are equally unaware of how serious the water crisis is," Dai said.
The report, Beijing's Water Crisis: 1949-2008 Olympics, says more than 200 rivers and streams can still be found on official maps but the reality is that little or no water flows in most of them.
Beijing is pumping out about 3 billion cubic metres of groundwater a year to keep up with demand - this is 500 million cubic metres more than the annual allowable safe limit. The Games would consume up to an extra 200 million cubic metres, adding an extra 5 to 10 per cent load on already depleted reserves.
Dozens of reservoirs built since the 1950s have dried up and the city's two biggest reservoirs, Miyun and Guanting, are at 10 per cent of their original capacity. Guanting is so polluted it has not been used as a drinking water source since 1997.
The Chinese experts, apart from Dai, who researched the report, are anonymous because the issue is so politically sensitive at a time when China is trying to show its best face to the world.
Olympic organisers argue that they have met all seven of the greening indexes they committed to in 2001, including increasing forest coverage to more than 50 per cent, creating 23,000 hectares of green belt land and increasing urban green coverage to more than 40 per cent.
The rehabilitation of barren Beijing - in 1950 the capital had less than 1.1.3 per cent of forest cover - has involved tree planting on a huge scale. Since 2001 more than 22 million trees have been planted and 15 big parks and 56 million square metres of lawn have softened the harsh urban landscape.
About a third of villages in the water source reserve zones now have sewage treatment and water is being recycled for irrigation and toilet flushing.
The United Nations' environment program's audit of Beijing's Olympic greening efforts, published in October, called the improvements impressive and said the $US12 billion of government investment in improving energy efficiency, waste management, providing cleaner transport, improving irrigation methods, and phasing out ozone-depleting chemicals had been well spent.
But the report criticised stubbornly high air pollution, the failure to offset greenhouse gases and too much emphasis on waste processing rather than waste minimisation.
Friends of Nature, an environmental non-government organisation, said the Government deserved some credit.
"The Government has actually done some things to improve Beijing's environment," Yi Yimin, a spokeswoman, said. "So it's not fair to simply say they are [window dressing on the environment] because even without the Olympics it would have done a lot.
"What is more accurate to say is that because of the Olympics, the Government has broadened and reinforced what it has already planned … Although there are temporary measures like limiting vehicles by even and odd numbers, most of other measures are long term."
Yi said environmental awareness within governments among the public was growing and national policies of reducing energy usage and cutting emissions were responsible.
"On the whole, we can say this is a 'Green Olympics' as most of the construction and running of Olympic venues and related facilities will be environmentally friendly," she said. "We can easily see how many new parks and water projects Beijing has built, but we regard substantial change of the environment which normally lies under the surface as more important."
*In 2007 new agricultural water use was halved to 1 billion cubic metres and 170 water-intensive industries, including cement and paper factories, were moved, closed or suspended. This included the massive Shougang iron and steel works, which alone saves 40 million cubic metres of water a year. It is being moved 100 kilometres away.
*The city has been opening a new sewage treatment plant every year since 2000 and it attained a 92 per cent sewage treatment rate last year, up from just 42 per cent in 2000.
*This year 600 million cubic metres of water will be recycled, 17 per cent of the city's water consumption. The huge Olympic Forest Park, north of the Olympic Green, will be supplied totally from recycled water, rain and floodwater.