BEIJING — The number of dead pigs found in a Shanghai river that provides drinking water to the Chinese financial hub has risen to 8,354, after local authorities pulled 809 more pigs out of the river on Friday.

The Shanghai municipal government has repeatedly assured the city's 23 million residents that tap water is safe. Shanghai locals, however, remain worried about water contamination from the swollen and rotting carcasses in the river.

The dead pigs are believed to be from hog farms in the upstream Jiaxing area in neighboring Zhejiang province. A surge in pig dumping has followed police campaigns against the sale of pork products made from diseased pigs.

Chinese state media say one Jiaxing hog farmer has admitted to pig dumping and is under investigation.

Related on HuffPost:

Loading Slideshow...
  • A villager dumps dead pigs into a decontamination storage built on a farmland in a town in Jiaxing municipality, east China's Zhejiang province on March 13, 2013. (AFP/AFP/Getty Images)

  • Employed villagers gather dead pigs in a town in Jiaxing municipality, east China's Zhejiang province on March 13, 2013. (AFP/AFP/Getty Images)

  • Employed villagers gather dead pigs in a town in Jiaxing municipality, east China's Zhejiang province on March 13, 2013. (AFP/AFP/Getty Images)

  • Employed villagers gather dead pigs in a town in Jiaxing municipality, east China's Zhejiang province on March 13, 2013. (AFP/AFP/Getty Images)

  • A dead pig floats in a river in a town in Jiaxing municipality, east China's Zhejiang province on March 13, 2013. (AFP/AFP/Getty Images)

  • Employed villagers gather dead pigs in a town in Jiaxing municipality, east China's Zhejiang province on March 13, 2013. (AFP/AFP/Getty Images)

  • Villagers dumps dead pigs into a decontamination storage built on a farmland in a town in Jiaxing municipality, east China's Zhejiang province on March 13, 2013. (AFP/AFP/Getty Images)

  • Workers collect dead pigs to deliver to a bio-safety disposal facility in Zhulin village of Xinfeng township in Jiaxing in east China's Zhejiang province Wednesday, March 13, 2013. (AP Photo)

  • In this photo taken Tuesday, March 12, 2013, a farmer pulls a sick pig to a bio-safety disposal facility at Zhulin village of Xinfeng township of Jiaxing city in east China's Zhejiang province. (AP Photo)

  • A worker hauls away dead pigs with a net in Zhonglian village of Jinshan district in Shanghai Wednesday, March 13, 2013. (AP Photo)

  • A worker in protective clothing prepares to haul away dead pigs pulled from the river along Zhonglian village of Jinshan district in Shanghai Wednesday, March 13, 2013. (AP Photo)

  • Sanitation workers (L) collect a dead pig from Shanghai's main waterway on March 11, 2013. (PETER PARKS/AFP/Getty Images)

  • In this photo taken Thursday March 7, 2013 and made available Sunday, March 10, 2013, dead pigs are strewn along the riverbanks of Songjiang district in Shanghai, China. (AP Photo)

  • A photo taken through the window on a boat shows dead pigs collected by sanitation workers from Shanghai's main waterway on March 11, 2013. (PETER PARKS/AFP/Getty Images)

  • A dead pig floats on the river Monday, March 11, 2013 on the outskirts of Shanghai, China. (AP Photo)

  • A sanitation worker watches a dead pig being collected from Shanghai's main waterway on March 11, 2013. (PETER PARKS/AFP/Getty Images)

  • A dead pig floats on the river Monday, March 11, 2013 on the outskirts of Shanghai, China. (AP Photo/Eugene Hoshiko)

  • Dead baby pigs float on the river Monday, March 11, 2013 on the outskirts of Shanghai, China. (AP Photo)

  • A dead pig floats among the rubbish on the river Monday, March 11, 2013 on the outskirts of Shanghai, China. (AP Photo/Eugene Hoshiko)

  • A sanitation worker collects a dead pig from Shanghai's main waterway on March 11, 2013. (PETER PARKS/AFP/Getty Images)

  • A sanitation worker collects a dead pig from Shanghai's main waterway on March 11, 2013. (PETER PARKS/AFP/Getty Images)

  • Authorities check the dead pigs, not seen, which have been pulled out from the river on a barge Monday, March 11, 2013 on the outskirts of Shanghai, China. (AP Photo/Eugene Hoshiko)

  • A dead pig floats on the river Monday, March 11, 2013 on the outskirts of Shanghai, China. (AP Photo/Eugene Hoshiko)

  • A resident looks at a dead pig floating on the river Monday, March 11, 2013 on the outskirts of Shanghai, China. (AP Photo/Eugene Hoshiko)

  • Workers look for dead pigs floating on the river Monday, March 11, 2013 on the outskirts of Shanghai, China. (AP Photo/Eugene Hoshiko)

  • Hundreds of Dead Pigs Found in Chinese River

    A discovery along the banks of Shanghai's Huagpu River. Dead pigs. More than 900 of them.