China has suspended power generation at a major Yellow River dam to contain diesel fuel that leaked last week from a pipeline -- the latest environmental disaster to affect China's waterways, considered among the world's most polluted.

Beginning Dec. 30, an estimated 100 tons of diesel fuel spilled into the Wei River, which feeds into the Yellow, a water source for millions of Chinese.

All six generators at the Sanmenxia power station were shut down on Saturday to hold contaminated water behind the dam and keep it from flowing toward major cities downstream that rely on the river for drinking water, said Yang Ming, a spokesman for the Sanmenxia Water Conservancy Bureau.

"We may suffer some economic loss for doing so, but we need to consider the overall situation," Yang said Tuesday by telephone from the bureau's headquarters in the northern province of Shaanxi.

Built in the 1960s, the Sanmenxia dam now generates 1.2 billion kilowatt hours per year -- a fraction of the 19 billion kilowatt hours per year generated by Shaanxi's seven power generating dams along the Yellow.

Authorities have already told 850,000 people in riverside communities to avoid using the Yellow for drinking or watering livestock.

However, in a statement issued late Monday, the Shaanxi provincial government said cleanup measures, including diversion channels, floating dams, and absorbing agents, had so far proven effective in containing the spill.

As of Monday, no oil slick could be seen on the Wei and oil concentration in the river averaged just 0.79 part per million (0.79 milligrams per liter), well within acceptable limits, the statement said.

The Yellow, China's second-longest river, has seen its water quality deteriorate rapidly in recent years due to rising industrial discharge and dropping water levels due to the diversion of water to major cities downstream, including Luoyang, Kaifeng and Zhengzhou.