The Pak Mun Dam (Thai: เขื่อนปากมูล, RTGS: Khuean Pak Mun, pronounced [kʰɯ̀a̯n pàːk mūːn]) is a barrage dam and run-of-the-river hydroelectric plant 5.5 km west of the confluence of the Mun and Mekong Rivers in Khong Chiam District, Ubon Ratchathani Province, Thailand.

[1] It was constructed by the Electricity Generating Authority of Thailand (EGAT) with support from the World Bank at a total cost of US$240 million, and completed in 1994.

[citation needed] In response to protests, the government opened the dam gates temporarily in June 2001.

Instead, the Thai Cabinet decided to close the gates for eight months each year from November 2002.

TDRI's report, published in 2000, concluded that "...EGAT over-stated the case of project benefits and did no justice to the method of benefit-cost analysis in exaggerating the value of net gains in power production and in claiming irrigation benefits on invalid grounds.