by Sara Gates / the Huffington Post

While China’s air pollution has reached hazardous levels in some major cities, chemical pollutants in the air are hardly the only problem. Entrepreneur Jin Zengmin, from the eastern coastal province of Zhejiang, has posted photos on Chinese microblogging service Sina Weibo to illustrate how rivers and other bodies of water in the country are also at risk of pollution.

One photo featured a trash-clogged river in the rural town of Ruian, Zhejiang. Along with this photo, Jin also posted a dare for the local environmental protection bureau chief to swim in the river and offered a 200,000-yuan reward (about $32,000). According to the South China Morning Post, bureau chief Bao Zhenming has refused to accept Jin’s dare, explaining that his department is “not responsible” for the pollution. Bao did say, however, that he alerted the water conservancy bureau of the contamination shown in the pictures.

Click over to the South China Morning Post to see photos of the polluted river.

According to China News, Jin accused a local factory of dumping industrial waste into the river, but Bao said the blame lies with the region’s overpopulation, the Shenzhen Daily reports.

Jin is not the only Weibo user upset with China’s water pollution.

According to the Global Times, a state-run news agency, concerns over groundwater pollution in Chinese towns are growing among social media users, who have followed Jin’s lead in accusing factories of dumping waste. However, the Times reports that government officials are constantly monitoring factories to ensure they are not “violating water discharge regulations.” Authorities in Weifang, located in the central Shandong province, have gone so far as to offer a reward for tipsters who report factories in violation.

As the Global Post notes, as many as 40 percent of China’s rivers are seriously polluted, according to statistics obtained by Voice of America. And that estimate, from January 2012, may be a conservative one. According to Radio Free Asia, the latest water survey data suggests 90 percent of groundwater in China is polluted.