Nearly 6,000 dead pigs have been found in Shanghai's Huangpu river, a key source of drinking water for millions of residents in China's largest metropolis, as the carcasses continued to clog the water body.
Workers have been busy collecting the corpses of floating pigs since Friday and many corpses remain in the river.
The source from where they are being dumped into the river continues to be a mystery as it is yet to be identified. The numbers touched nearly 6000 today, state run Xinhua news agency reported.
This morning, 20 dead pigs were collected within 10 minutes, most of which had already started to decompose.
"It's common to find one or two dead pigs in the water, but too many corpses were found this time," said Gao Dongsheng, a worker who has been collecting dead pigs since Friday.
Tags pinned to the ears of the pigs for tracing purposes indicate that they may have come from the upper reaches of the Huangpu River in Jiaxing City, east China's Zhejiang Province.
The tags, however, only indicate the animals' birthplace. Laboratory tests found porcine circovirus, a virus that can spread among pigs but not to human beings, in one water sample taken from the Huangpu River, the report said.
All other tests showed no signs of irregular contaminants or disease, according to sources with the municipal agricultural commission.
The river is a major source of drinking water for Shanghai, an eastern metropolis of 23 million people.
"The dead pigs will float to the area near the Songpu Bridge, one of the major water intakes of the Huangpu River, if they are not collected in time," said Chen Zhenlou, a deputy to the National People's Congress and a professor with the College of Resources and Environmental Science, East China Normal University.
An automatic water quality monitoring network should be built to constantly check for changes in relevant indicators, Chen said.