The cadmium toxic slick in Guangdong's Beijiang River is expected to return to a safe level before it reaches other cities downstream, according to a report released by the local authority yesterday.

Since measures were launched to disperse the toxic slick in the southern Chinese province on Friday, the environmental protection watchdogs have dumped 380 tons of chemical dilutant on the toxic slick.

"The cadmium content of the slick dropped 20 percent on Saturday," Li Zisen, the chief leader of the watchdog team, said.

It is planned that a total of 1,200 tons of the chemical dilutant will be dumped on the slick.

Over 54 cubic metres of water are being released per second from Nanshui Reservoir in Shaoguan, a city upstream from the slick, in an attempt to dilute the toxic spillage.

The cadmium content of the slick at Nanhua Waterworks near Yingde dropped to 0.012 milligrams per litre on Saturday, a little higher than safety level of 0.01 milligrams per litre, according to tests taken by Guangdong provincial health department.

"The chemical level is expected to return to normal before it reaches Feilaixia Dam in Qingyuan, more than 100 kilometres downstream from Yingde," said yesterday Zhang Jianjun, spokesman of Qingyuan municipal government. The slick is flowing at a speed of 4.5 kilometres per day, he said.

The slick was caused by a spillage of more than 1,000 tons of heavy cadmium contaminated water from Shaoguan Smelting Plant on December 15. The event caused huge economic losses with the total direct and indirect loss amounting to 150 million yuan (US$18.75 million).

The director of the Shaoguan plant Zhang Weijian was suspended from office on Friday for further investigation into the incident.

The other 14 smelting plants in Shaoguan have been closed.

Guangzhou and Foshan, towns downstream from Beijiang, are keeping a close eye on the slick's developments.

The drinking water emergency measures brought in on Wednesday by the two cities are still in effect now.

It was reported that Tianhe, one of Guangzhou's 10 districts, stopped its water supply yesterday afternoon, though this was denied by the government.

"I didn't hear anything about a suspension of the water supply," Lu Shaokun, spokesman of Guangzhou Garden Bureau, said yesterday.