According to published information, the Hang Dong B project has a designed capacity of 28MW and is located on the Be Stream, which runs through Suoi To and Ta Xua communes in Son La Province.

The Be Stream covers a basin of about 202 square kilometers and is a tributary of the Sap Stream, which flows into the Da River at Bac Yen Commune in Son La.

The project area is characterized by steep, rugged mountains and deep valleys, forming a network of branching streams. Construction began in August 2016 but faced challenges due to difficult terrain and the need to use forested land. In 2018, the developer revised the project design, relocating the dam 3km downstream and increasing installed capacity from 20MW to 28MW.

A dense cluster of hydro plants in the Sap Stream basin

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Diagram showing location and cascade structure of hydropower plants on the Sap Stream.

In June 2025, the Son La Provincial People’s Committee approved the conversion of over 25 hectares of forest land for the project. Over 100 hectares have already been granted land use rights.

The Sap Stream is fed by the Be and Hang Dong streams. According to the small and medium-sized hydropower plan, the basin hosts eight cascade hydro plants. Hang Dong currently operates two plants - Hang Dong A (16MW) and Hang Dong A1 (8.4MW) - while Be Stream hosts only Hang Dong B. On the Sap Stream itself, there are the Suoi Sap 1, 2, 2A, 3, and Hong Ngai hydropower plants.

The Hang Dong B project requires over VND 1.203 trillion (approx. USD 48.8 million) and uses two 14MW horizontal Francis turbines. Its EIA notes risks such as fire, landslides, subsidence, or dam failure, but the investor has committed to installing monitoring systems and emergency response measures.

Coc Re 2 hydropower plant to tap Tuyen Quang’s river network

The EIA for the Coc Re 2 project in Trung Thinh Commune, Tuyen Quang, indicates the project will use over 24 hectares of land and cost more than VND 193 billion (approx. USD 7.8 million). Originally part of Ha Giang Province’s hydropower plan, the project has now been transferred to Tuyen Quang.

Coc Re 2 has a capacity of 5.5MW and will generate 19 million kWh annually. It will be built on the Ta Nam Lu – Na Tuong – Ta Lai stream system, part of the Chay River basin. The project area mainly comprises forest production land and is not home to any rare or endangered species.

It is the second hydropower plant planned for this river segment. Upstream is the proposed Coc Re 1 (4.5MW) plant, while downstream lies the Chay River. The approved master plan includes five hydro plants on the Chay’s upstream section.

The plant site is 1.6km from Chay River 5 Hydropower Plant, 1.2km from the nearest residential area, 20km from Xin Man Commune's administrative office, and 11km from Trung Thinh Commune’s headquarters.

Technical specifications and impact scope

The project includes a combined dam and spillway, surge tank, and pressure pipeline leading to the powerhouse. It will use two horizontal Francis turbines. The reservoir created by the dam will have a total capacity of 9,000 cubic meters, with an active capacity of 4,000 cubic meters. The dam crest will sit at an elevation of 513 meters.

Vu Diep