“Yala Province” is a province among 3 southern border provinces which has a diversity of races, languages and culture. However, it has been combined together bringing about social and community development including the power system to be secure and stable. The construction of “Bang Lang Dam” is the development of water source according to Pattani River Basin Development Plan. Bang Lang Dam is the first multipurpose dam of the South providing many benefits to people in the region ranging from electricity generation, irrigation for cultivation, flood mitigation at the lower Tapi River basin, freshwater fishery and tourism. The dam is one of tourist attractions in Yala Province which is beautiful, safe and worthwhile for a visit.

The construction of Bang Lang Dam began in July 1976 and completed in June 1981. Their Majesties King Bhumibol and Queen Sirikit accompanied by Her Royal Highness Princess Maha Chakri Sirindhorn performed the opening ceremony of the dam on 27 September 1981. At present, the power plant of the dam has contractual generating capacity of 84 MW.

On the occasion of the royal visit to the construction site of Bang Lang Dam in 1978, His Majesty King Bhumibol had an idea of making use of the overflow water from the weir to the dam reservoir by generating electricity from a small power plant in order to develop the local water source for the optimum benefit. 

Thus, in 1981, EGAT constructed the first underground power plant at Moo Ban Sunti 1, Cho Sub-district, Bun Nung Sta District, Yala Province. A generator of 1.275 MW and a water pipe of 1,800 m in length were installed at the power plant. The power plant could supply electricity in October 1982 generating an average annual electric power of 6 million kWh.

Ban Sunti Hydro Power Plant has an automatic control which can be operated from Bang Lang Dam Power Plant. It is a small power plant which uses high technology and operated solely by the Thai engineers.