Guangdong province has created a task force to tackle a serious water pollution problem after storm runoff contaminated the river that supplies drinking water for about 2 million urban residents in Jieyang.

Heavy rainfall washed garbage and waste along the banks into the upper river starting on Tuesday, leading to excessive amounts of ammonia and nitrogen in the drinking water supply, according to a statement by Jieyang environmental protection bureau.

"Environmental protection agencies and related departments have promised to punish those shown by an investigation to have illegally discharged wastewater into the river," the statement said.