Chao Lake, or Chao Hu, (Chinese: 巢湖; pinyin: Cháo Hú), is a lake located at the juncture of Chaohu and Hefei cities in Anhui Province, China. It is the largest lake in Anhui and one of the five largest freshwater lakes in China. Mushan Island is situated within the lake. About 5 million people live near the lake, and use it for irrigation, transportation and fishing. Heavy use of the lake in recent years has led to eutrophication and silting. Due to China's rapid economic growth, the lake is now one of China's most polluted lakes.
Noted tourist sites around the lake include Mount Mu, Zhongmiao Temple, Tongyang River, Mount Yinping, and the Immortals Cave. The silver fish, shrimps, and crabs of Lake Chao are called the Three Treasures, and it also enjoys the grand name of "Land of Plenty".
According to legend, the site of the lake was once a prosperous city named Chaozhou. Because of sins of its people, it was cursed by the heavens and ordered to be destroyed by flood. The task was to be carried out by a white dragon who was only able to find one good person, an old lady ('Lao' in Chinese) surnamed Jiao. After the destruction of Chaozhou, only the old lady and her daughter were saved. They became the two islands emerging from the lake. This legend may in fact be rooted in geological history, since Lake Chao is located on the intersection of several major faultlines, of which the most famous is the Tan Lu Fault which caused the great 1976 Tangshan earthquake in its northern section. It is also regarded as one of the most polluted lakes on the planet and has featured on many lists of similar attribute.