The Hoa Binh hydropower dam, Vietnam’s so-called ‘century project’, celebrates its 25th anniversary this year. 

Built in the Black River basin in the northern mountainous province of Hoa Binh, at the time of its conception in 1979, Hoa Binh was the largest hydroelectric dam in Southeast Asia.

 Hoa Binh Dam has a significant place in history. It was built during the country's transition period, fresh from the end of the Vietnam War, a trade embargo by the U.S. and a fight against the genocidal Pol Pot regime in Cambodia, and a border war with China looming.

The construction of the dam was supported by the Soviet Union all the way through, designing, supplying equipment, supervising, and helping it go on stream. Construction began on November 6, 1979, with 40,000 officers, engineers and workers and 750 Soviet experts. It was completed 15 years later on December 20, 1994.

It is 128 m high and 734 m long with a total of 18 floodgates that can discharge 35,400 cubic meters of water per second and a capacity of nearly 10 billion cubic meters.

The dam's grout curtain, which protects the foundation from seepage, was built using the clay core-wall rockfill technique, only the fourth dam in the world to be built this way. It helps the dam withstand powerful earthquakes and the disparity between the volumes of water flowing into it in the dry and rainy seasons.

The underground construction enabled the plant to begin operating soon and in stages. The first two of the eight units began operating in December 1988.

The underground power plant consists of eight generation units with a combined capacity of 1,920MW, or 40 percent of the total capacity in the country then.

A worker checks the power generation parameters.

Under the concrete block which was used in the first river damming operation lies the letter from the people who built Hoa Binh hydropower to future generations, written in Vietnamese and Russian. It is set to be opened in 2100.

A total of 168 people, including 11 Soviets, died during the construction. Their names are inscribed on a monument built on a bank of the dam.