Poyang or P'o-yangboth: pô-yäng [key], shallow lake, c.1,000 sq mi (2,590 sq km), N Jiangxi prov., SE China; one of China's largest lakes. It serves as a natural overflow reservoir for the Chang (Yangtze) River, to which it is connected. It receives the Gan River and several smaller rivers. The lake fluctuates in size significantly with the seasons, decreasing in winter and increasing in summer. The lake is a winter home for migratory birds. In recent years water levels, especially in the winter, have dropped more than in the past, due to the effects of sand mining in the lake and of the Three Gorges Dam upstream on the Chang. Water quality has also been affected by untreated wastewater, and these changes and overfishing have reduced fish stocks in the lake. The lake basin is one of China's richest rice-producing regions.

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