P'o-yang (both: pô-yäng), 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. Sand is mined from the lake, which also is a winter home for migratory birds. The lake basin is one of China's richest rice-producing regions.