Yangzonghai Lake (simplified Chinese: 阳宗海; traditional Chinese: 陽宗海; pinyin: Yángzōng Hǎi) (given on some maps as Yangzong Sea, though it is fresh water) is located between Yiliang County, Chenggong District and Chengjiang County, 45 kilometers east of Kunming City in Yunnan Province, China.

But as of September 2008, it was officially considered unfit for drinking, swimming in or fishing in, when the provincial government announced high levels of arsenic in its waters.

The company allegedly failed to build the legally required treatment facility for its wastewater, with years of accumulated arsenic seeping into the local water table.

In February 2008, Kunming Communist Party Secretary Qiu He (仇和) visited Yangzonghai, warning local enterprises that the lake must not become a "second Dianchi".

An article posted on xinhuanet.com, October 22, 2008 said: "Three executives of a company were arrested and 12 government officials fired in connection with polluting a lake in southwest China's Yunnan Province, according to a provincial inspection department spokesman on Wednesday.