Khlong Saeng is a wildlife sanctuary in southern Thailand, in western Surat Thani Province. The wildlife sanctuary is named after the river Saeng, a tributary of the Phum Duang River. The sanctuary includes an area of 1,155 km2 of Khiri Rat Nikhom District and Ban Ta Khun District, north of Khao Sok National Park and Ratchaprapha Dam. Most lowland areas in the Khlong Saeng valley were flooded with the construction of the dam and the creation of Cheow Lan Reservoir.