The Lanzhou River in Shanghai is clearing again, and Liu Deqiang, 59, has resumed his habit of practicing t'ai chi along its banks.

"The black oil floating on the river has disappeared and the water has stopped stinking," said Liu.

The 740-metre-long Lanzhou River is a branch of the Huangpu River, which winds its way through Shanghai from south to north. Liu used to exercise along the banks almost every day.

"I now see people fish along the banks sometimes," Liu said.

Then, on a morning early this month, he surprisingly found the river had turned black and foul overnight.

Liu was referring to an environmental crisis in early May on the river, when almost 100 tons of heavy oil accidentally leaked into the river.

A pipe at a workshop at the nearby Baosteel Group's Shanghai Ergang Co broke suddenly and about 100 tons of oil leaked.

The glue-like oil spread fast and covered the whole river and all sewage pipes connected with it. And many of the pipes were clogged.

"Fortunately the gates to the Huangpu River and another branch were closed then and the pollution was not extended," said an official surnamed Qian, from the Urban River Management Office of Yangpu District. he declined to give his full name.

Straw and pads were used to absorb the oil from the river and the water was then discharged into cisterns at a nearby pumping station.

In the station, workers used equipment to remove the oil little by little, and then the water was piped back into the river.

At the same time, the office pumped water from the Huangpu into the river every day to help dissolve the pollution.

"However, the pollution which has changed the content of the water cannot be totally dissolved in just a couple of months," said Tao Kanghua, an ecological expert who has been working with the government on environmental protection.

"Accidents like that usually cost a lot to recover from," said Tao. "The company that is responsible for the accident could face a serious penalty,"

The Lanzhou River leak was quite serious and has caused severe influence on the water area, according to Qian.

"Pollution as serious as this was never seen in this river before," said Qian. "Lots of complaints were filed from nearby area residents."

"The river including its silt looked all dark, and you could smell the stench when you were 10 metres away," said Liu Deqiang.

Tao pointed out that heavy oil leaks like this have occurred at least 10 times in local rivers in the past decade, most with large amounts spilled.

But they have only contributed to part of the city's river pollution problems.

Industrial discharge and human sewage still make downtown rivers fouled and black.

It is estimated that Shanghai is producing more than 4 million tons of industrial sewage every day and only 65 percent of the substances are properly processed before flowing into rivers.

More than 1 million tons of the effluent is discharged into rivers or sea directly.

Some grossly polluting factories continue pouring industrial sewage into rivers without any treatment despite the government strictly prohibiting the practice.

A report compiled by the Shanghai Water Administration shows that only 13.1 percent of the water in Shanghai's 16 main rivers is considered to have a good quality in 2004. And the quality of nearly 70 percent water of the city is poor.

Shanghai started a three-year environmental protection project in 2002.

Last year, treatments have been applied to 125 of the city's 201 rivers and creeks and the quality of the water has been visibly improved.

According to the plan, Shanghai will clean the rest of 76 odorous rivers in downtown area and add 50 kilometres of additional sewage pipes to waste water disposal factories by the end of this year.

Shanghai listed water protection as one of the top challenges for this year.

Pudong District alone plans to spend more than 100 million yuan (US$12.1 million) to clean up the water system in the area and close down heavy polluters along the rivers.

(China Daily May 31, 2005)