Lake Chao is located 15 km southeast from Hefei City, the capital of Anhui Province. It is one of the five largest freshwater lakes in China, and is the largest lake in the Province. The life of the lake is about 10 thousand years.

The lake is famous for its beautiful landscape and historic sites, and is extensively used as water sources for drinking, irrigation, fishery and transportation. About 5 million people live around the lake. In 1962, a dam was built at the only outflowing river. Control of water level has brought about some merits for irrigation and transportation, but at the same time it resulted in some demerits. The most evident effect was the reduction of fish production.

Owing to the rapid development of industry, fast increase of population and establishment of water conservancy facilities, the lake has suffered from eutrophication and silting in recent years (Q).