So say official sources, which point to drainage-related problems.
Beijing (AsiaNews/Agencies) Most of the Yellow River is so polluted that its waters are not safe for swimming, much less for drinking.
The Xinhua agency official government bureau said around three-quarters of the river, which supplies water to 12% of 1.3 billion Chinese and 15% of agricultural zones, have been severely contaminated by sewage dumping, industrial waste, fertiliser and other polluting substances.
"A government report says more than 72.3% of the waters of the Yellow River have dropped below third category," writes the agency, referring to national standards which assess the quality of water for drinking, for marine life and for swimming.
The river, which takes its name from the yellow-brown colour of its sand, was known for a long time as "the mourning of China", because of its changing currents and inundations which have killed millions of people. It is estimated that around one million people died when the river overflowed in 1887: this was the worst flooding in the world in modern history.
China is facing a severe hydraulic crisis 300 million people do not have access to drinking water and the government is trying to clean the main water flows like the Yellow River, the Huaihe and the Yangtze. But these campaigns have obtained only meagre results because of fragmentary local interventions and knowledge of industrial activities which is less than complete.
The damage done to the Yellow River, which flows through the country from west to east, has resulted in the loss of 11.5 billion yen in a year. China has set up more than 20 hydro-electric plants along the river and plans to have 38 in all.
Exploitation of hydraulic resources in the valley of the Yellow River is at 70%, much higher than the danger level widely taken to be 40%.
The problem can only get worse when the river forms part of an ambitious project for the diversion of southern and northern waters, which foresees the pumping of waters from southern to arid northern flows.
When the project is completed in 2050, around 45 billion cubic metres of river water will be sent north each year, at a cost of no less than 500 billion yen, two times as much as the dam of the Three Gorges.The Agency for National Environmental Protection admits that most of the water will not suitable for nutritional use, unless local governments and industries provide for a considerable reduction in pollution.