Caddo Lake is the only natural lake in the entire state of Texas.
Caddo Lake (French: Lac Caddo) is a 25,400 acres (10,300 ha) lake and wetland located on the border between Texas and Louisiana, in northern Harrison County and southern Marion County in Texas and western Caddo Parish in Louisiana. The lake is named after the Southeastern culture of Native Americans called Caddoans or Caddo, who lived in the area until their expulsion in the 19th century. It is an internationally protected wetland under the RAMSAR treaty and features the largest Cypress forest in the world. Caddo is one of Texas’ few non-oxbow natural lakes and is the 2nd largest in the South; however, it was artificially altered by the addition of a dam in the 1900s.