The southern Chinese cities of Guangzhou and Foshan were ordered Wednesday by local provincial government to soon start emergency plans to ensure safe drinking water supplies to their residents as a toxic slick approaches. 
   
The river pollution was caused by an excessive discharge of cadmium from a state-owned smeltery in the Beijiang River, a major source of drinking water for cities in the northern part of south China's Guangdong Province.
   
The local environmental protection departments found in the smeltery in Guangdong's Shaoguan City that the excessive discharge of waste has made the volume of cadmium in the river section of Shaoguan surge nearly 10 times above the safety standard, "seriously affecting" the water safety in the river's lower reaches.
   
The smeltery has halted operation and closed the waste water outlet blamed for excessive discharge, according to the environment protection office of Shaoguan City.
   
Local governments along the Beijiang River have set up 20 monitoring posts to keep a close watch on the water quality.
   
The density of cadmium kept dropping after the local governments began diluting the polluted water by increasing the discharge of the water reservoirs at Beijiang's upper reaches, according to environmental protection experts.
   
Experts forecasted that the diluted water will likely not threaten the drinking water source for the downstream cities of Foshan and Guangzhou. Nevertheless, the two cities have been askedto start emergency plans to ensure safe drinking water.
   
Zhang Lijun, deputy director of the State Environmental Protection Administration, arrived Tuesday at Yingde, which is about 90 km south of Shaoguan, with a group of 14 experts on environmental protection, city water supplied, agriculture and health to deal with the possible water crisis.
   
The toxic click arrived at Yingde, a city of more than 100,000 urban residents, Tuesday night.
   
Yingde has begun to build a 1.4-km-long water pipe linking with the supply line of a reservoir in a suburb to send clean water directly to the urban district.
   
A large quantity of water carriers, including 15 fire engines, have been used to send drinking water to the urban district.
   
So far, local people's lives remains normal along the 470-km-long Beijiang River, which runs from north to south into the Zhujiang (Pearl) River flowing through Guangzhou, according to the provincial environmental protection department.
   
Cadmium is a soft, bluish-white metallic element occurring primarily in zinc, copper, and lead ores, that is easily cut with a knife and is used in low-friction, fatigue-resistant alloys, solders, dental amalgams, nickel-cadmium storage batteries, nuclear reactor shields, and in rustproof electroplating.
   
It is the second major water pollution incident in China in recent days.
   
A chemical plant blast on Nov. 13 in Jilin City of northeast China's Jilin Province resulted in a serious leakage of poisonous substances of cancer-causing benzene and nitrobenzene into the Songhua River, which forced a four-day water cut-off to Harbin, capital of neighboring Heilongjiang Province.
   
Chinese workers successfully dammed a waterway in the Heilongjiang River Wednesday morning before the chemical spill arriving at the Russian city downstream.