If one strolls through the villages along the shores of Yangzonghai Lake, it is impossible to avoid coming across signs announcing the "Three Prohibitions" – drinking lake water is prohibited, swimming or bathing in lake water is prohibited and consuming aquatic products from the lake is prohibited.

The 26,000 villagers in the area can no longer use the lake as a source of drinking water – they now depend upon bottled water delivered by the government. Unfortunately, Yangzonghai's pollution, most of which has taken place since 2001, parallels what has been happening to lakes and rivers across Yunnan province in recent years.

According to a recent Tencent report, water quality across Yunnan's network of rivers and lakes has been deteriorating steadily over the last several years.

Of the 53 lakes and reservoirs in the province, 27 are not considered "environmentally functional". Of the 75 main rivers in the province, 22 percent are heavily polluted.

Aside from arsenic-polluted Yangzonghai, the report said there are five other lakes in Yunnan that are not able to be considered "environmentally functioning". This includes Dianchi Lake's Caohai and Waihai sections, Qilu Lake, Xingyun Lake and Yilong Lake.

Of these bodies of water, Caohai and Qilu Lake suffer from the heaviest pollution, while the pollution levels at Waihai, Yilong Lake and Xingyun Lake – which suffers from petroleum pollution – were slightly lower.

The report also said that Erhai Lake in Dali is currently at a perilous turning point between medium and heavy eutrophication, which eventually removes oxygen from a body of water and leads to the destruction of all animal life.

Across Yunnan, wastewater treatment, a crucial component in reducing river and lake pollution, is practically nonexistent, according to the report.

At present, there are only 38 wastewater treatment facilities in Yunnan, 10 of which are located in Kunming. There are 90 counties and municipalities in the province with no wastewater treatment facilities whatsoever.

Compounding the problem of too few wastewater treatment plants is the lackluster condition of existing facilities. In a spot check of 13 wastewater treatment facilities in Yunnan by the provincial environmental supervisory unit, it was discovered that six of the plants were incapable of "normal operations".

To further compound matters, landfills across the province are seeping pollution into underground water supplies, the report said.