The fetid smell of rotting pork surrounds the Huangpu River in Shanghai as workers continue to remove dead pigs from the water in a scene grisly beyond imagination. So far, more than 2,800 pig carcasses have been fished from the river; the first bodies were discovered on Thursday.

Shanghai city officials say that the pigs include both piglets and fully-grown adults, some weighing hundreds of pounds.

State news agency Xinhua reported that tags affixed to the pigs' ears indicated they came from upstream on the river, which flows through the center of Shanghai and is an important source of the city's drinking water.

Shanghai's agricultural commission said that some of the pigs had tested positive for porcine circovirus, a common swine disease. It is believed that the pigs were dumped in the river after succumbing to illness.

A local newspaper in Zhejiang province, near Shanghai, noted last week that tens of thousands of pigs had died of an animal disease in a major pig-farming village in the past two months, reported CNN.

"According to our records, 10,078 pigs died in January, another 8,325 died in February. More than 300 pigs die everyday in our village, and we barely have any space left to dispose of the dead pigs," a local villager said. Chinese law requires farmers to dispose of dead animals at community disposal sites or bury them with proper disinfectant.

The affected portion of the river accounts for more than 20 percent of the raw water supply to the Shanghai's 23 million people, according to the water bureau.

The government is trying to quell fears that serious water contamination may have already occurred, and is hoping to assure people that the water is safe to drink. But concerned residents are calling for an in-depth investigation. River pollution is already a major problem with factory waste and untreated sewage finding their way into the water supply. To that end, Nestlé’s bottled water business in China alone climbed 27 percent last year largely due to concerns about polluted water supplies. Sales have gone from $1 billion in 2000 to $9 billion in 2012.

Related China stories on MNN:

Thousands of dead pigs found in Shanghai river
Sanitation workers in China continue to remove pig bodies from the river as concerns about drinking water safety increase.