Pollution Killing River They Said Was Too Big to Poison

China's biggest river, the Yangtze, is being poisoned by pollution, the state media reported yesterday in an unusually outspoken call for an environmental clean-up. Amid growing concern that economic development is inflicting an unsustainable toll on China's ecology, the Xinhua news agency quoted hydrologists as saying that the water is "cancerous" and a threat to marine life and drinking supplies in 186 cities along its banks.

The 3,964-mile-long river supports 400 million people - one in every 15 people on the planet. Its vast delta, which covers the megacities of Shanghai, Chongqing, Wuhan and Nanjing, is the powerhouse of China's economy, accounting for 40% of the national GDP. Despite the pollution problems that have ruined most of China's rivers, it has long been assumed that the Yangtze was too big to poison, because toxins were diluted and flushed by the 900bn tonnes of water that flow into its estuary every year.

But the Xinhua report - the latest in a series of alarm calls by the domestic media - painted a grimmer picture. Yuan Aiguo, a professor with the China University of Geosciences, told the agency: "Many officials think the pollution is nothing for the Yangtze, which has a large water flow and a certain capability of self-cleaning, but the pollution is actually very serious."

He predicted that 70% of Yangtze water could be classed as unusable within five years unless tougher measures are introduced to curb toxic discharges.

Government advisers warn that 25bn tonnes of waste water is dumped in the river every year, 80% of it untreated. Most comes from factories and cities, but the vast majority of the 21,000 ships that navigate the river each year also ignore regulations banning the discharge of sewage. This has created a pollution belt stretching hundreds of miles from Chongqing to the estuary near Shanghai, that is killing the river.

Lu Jianjian, a professor at Shanghai's East China Normal University, noted that the number of marine species has declined from 126 to 52 during the past 20 years of breakneck development. Xinhua quoted other experts who warned that the level of pollution would also kill off plants and turn the Yangtze into a dead river,

No mention was made of the politically sensitive Three Gorges dam, but environmentalists have blamed the giant concrete barrier for a deterioration of water quality and declining fish stocks. Further pressure on the river will come from a 500bn yuan (£35bn) plan to divert water from the Yangtze to the arid north of China via a series of canals. When this is completed in 2050, the government predicts that 45bn cubic metres of water will be transferred hundreds of miles to Beijing and other drought-stricken cities.