Drinking water for 80,000 residents of Yueyang County in central China's Hunan Province has been suspended after dangerous levels of arsenic were found in local water sources.

The discovery was made on Friday, but after emergency measures local authorities say the water is now safe, and taps will be turned back on today.

Primary investigations showed that the pollution was caused by Haoyuan Chemical Plant and Taolin Lead and Zinc Chemical Plant in Linxiang, a city 50 kilometers upriver of the county on the Xinqiang River, Pan Yue, vice-minister of the State Environmental Protection Administration (SEPA), said yesterday in a news release.

The two suspected enterprises have been shut down and their top managers are in custody, Pan said. Charges were not immediately available.

The pollution was discovered during a routine water quality check of the river, which contained a level of arsenic "10 times higher than official standards," Xinhua News Agency said.

The two plants have never conducted any environmental assessments, nor did they treat waste water before discharge, Pan said.

"Investigations showed that the two plants (Haoyuan and Taolin) respectively directly discharged five tons and 200 tons of waste water with a high concentration of arsenic into the Xinqiang River each month," Pan said.

However, an on-the-spot test showed that the water in Dongting Lake, the nation's second largest freshwater lake, was clean at the mouth of the Xinqiang River, he noted.

The water quality of Yangtze River, which is at the east end of the lake, has not been affected, and residents downstream need not worry about the safety of the drinking water, SEPA officials said.

No people have been reported poisoned in Yueyang County, said Zhang Zhimin, vice-director of SEPA's quick-response centre for emergencies, who participated in a task force dispatched to the site.

(China Daily September 12, 2006)