Zengwen Dam, formerly spelled Zengwun Dam or Tsengwen Dam, (Chinese: 曾文水庫; Hanyu Pinyin: Zéngwén Shuǐkù; Tongyong Pinyin: Zéngwún Shuěikù; Wade–Giles: Tseng2-wen2 Shui3-k'u4) is a major earthen dam in Dapu Township, Chiayi County, Taiwan on the Zengwun River. It is the third tallest dam in Taiwan, and forms the largest reservoir in Taiwan by volume. The dam regulates the flow of the Zengwun River for irrigation of the Chianan Plain, Taiwan's most productive agricultural region.