A chemical plant in Hunan Province has been accused of polluting a river by discharging waste water containing high levels of plaster, damaging local agriculture and making residents ill.

Waste water from Hunan Nonferrous Xiangxiang Fluoride Chemical Company, a fluoride material producer, has reportedly been flowing into the nearby Lianshui River that runs across Xiangxiang, a city of 880,000 people, Sanxiang Metropolis Daily reported.

A huge plaster hill was erected outside the chemical plant with a pool atop it to contain and process waste water, the report said.

The waste water from the chemical plant was discharged through a channel from the pool to the Lianshui River several kilometers away, turning the river yellow for several kilometers and making nearby farmland barren, according to the report.

Nearby residents complained that the pollution had been going on for a long time with the water having a strong smell of plaster, forcing them to  fetch water from several kilometers away and never use the polluted water for drinking or irrigation, according to xtol.cn, the local government's news portal.

However, the deputy Party head at the chemical plant, Tian Genxin, said the plaster was a harmless chemical byproduct, which mainly contained calcium sulfate that would not harm people's health.

The local environmental protection authority dispatched a special team on Monday to investigate the pollution after a Web user posted several horrible pictures about the plaster hill on Sunday. It has also required the chemical plant to stop discharging waste water from the plaster pool on the hill immediately, according to the website yesterday.

However, the initial outcome of the investigation found that the pH of the waste water met national standards. "It is fine to drink the water from the pool since it is alkali with pH 8," according to Chen, an official with the local environmental protection bureau.

Cheng, the head of Xiangxiang Environmental Protection Bureau, told the Global Times yesterday that the investigation was ongoing and that no conclusion could be drawn at present.

According to Tian, the chemical plant would invest 30 million yuan ($4.7 million) to improve the waste water disposal system. Calls to the chemical plant went unanswered by press time yesterday.