Thac Ba Hydropower Plant is constructed on Chay River in Yen Binh district, Yen Bai province. This is the first hydropower plant of Vietnam which was assisted by the former USSR, now is the Republic of Russia.

The plant was commenced on August 19^th 1964 and inaugurated on October 5^th 1971.
The first unit was commissioned on October 5^th 1971.

The second and third units were commissioned on March 10^th 1972 and May 19^th 1972, respectively.

Salient parameters of the plant are as follows:

- Catchment area:  6,430km²

- Installed capacity: 120MW.

- Maximum height of dam:  48m.
- Dam length: 657m.
- Dam volume: 1.33 million m³.
- Effective storage capacity of the reservoir: 2,160,000,000 m³.
- Total storage capacity of the reservoir: 2,490,000,000 m³.
- Reservoir surface area corresponding to normal water level: 235km².
- Maximum length of the reservoir: 60km.
- Normal water level: +58.0
- Flood water level 0.01%: +61.0
- Flood water level 0.1%: +59.65
- Flood water level 1%: +58.85
- Dead water level: +46.0
- Water level prior to flood: +50.3
- Maximum flood release capacity: 3,650m³/s.

- Average electricity output: 400 million kWh/year.