BEIJING, Jan 5, 2010 (AFP) - Two tributaries of China's Yellow River have been "seriously polluted" by an oil spill, further contaminating badly tainted drinking water resources, the government said Tuesday.
Water quality monitors at the Sanmenxia reservoir detect traces of diesel in the Yellow River in Sanmenxia on January 4 (AFP photo)
Up to 150,000 litres (40,000 gallons) of diesel spilled into the Chishui and Wei rivers on Wednesday last week after a pipeline operated by China's largest oil producer, China National Petroleum Corp., ruptured, state media said.
"Due to this incident, the Chishui river was seriously polluted and the Wei river was relatively seriously polluted," the government in northern Shaanxi province said in a statement posted Tuesday on its website.
But it said the pollution on the Wei river had been "effectively controlled".
Water quality on the two rivers had on Monday reached grade five, the worst level in China's pollution monitoring scale, after falling off the register following the oil spill, it said.
Level five water is unfit for drinking, but can be used for agricultural purposes, according to government standards.
The two rivers flow into the Yellow River, one of China's longest rivers and the source of drinking water for millions of people, including residents of eight cities that lie downstream from the oil spill, Xinhua news agency said.
On Sunday, diesel was detected in water in the Sanmenxia reservoir on the Yellow River in neighbouring Henan province, it said.
In an effort to contain the pollution, authorities shut down electricity production on the Sanmenxia dam in an effort to keep the contamination from flowing downstream to the cities of Zhengzhou and Kaifeng, the report said.
The two cities, with a total population of nearly 3.5 million people, get up to 95 percent of their tap water from the Yellow River, the report said. Residents in the cities have long depended on bottled water for drinking.