BEIJING (AP) – The number of dead pigs found in a Shanghai river that provides drinking water to the Chinese financial hub has risen to 7,545, after local authorities retrieved 944 more pigs Thursday.

The Shanghai municipal government has repeatedly assured the city’s 23 million residents that tap water remains 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.