Hydropower project in Cambodia helps fish to come home

STUNG TRENG - In early April in Sesan district of Stung Treng province, Cambodia, the reservoir of Lower Sesan II Hydropower Station was sparkling with water merging with the azure sky.

On the right bank of the dam, a clear stream flows through the woods downstream of the saddle dam. This is the nature-like fishway of the station.

The $781 million project is a three-way joint venture of China's Huaneng Hydrolancang International Energy, which has a 51-percent stake, Cambodia's Royal Group (39 percent) and Vietnamese EVN International Joint Stock Company (10 percent).

The 400-megawatt dam is the largest and the seventh one built by China in Cambodia. The Lower Sesan 2 dam, 56.5 meters tall, covers a 36,000-hectare plot.

Yan Xiang, deputy general manager of Lower Sesan II Hydropower Company, who is in charge of the operation of the hydropower station, said: "We have always been adhering to the policy of 'protecting in development and developing in protection', attaching great importance to the natural and ecological environment so as to provide green energy to Cambodia and the Belt and Road cooperation."

When talking about the fishway, engineering manager Nong Zuguan, who is responsible for the construction management of the fishway, said: "We made it into a natural fishway to fit into the surrounding environment, like a natural river. This is the way the fish came home."

For the 2,900-meter-long fishway, the maximum water level difference between the upstream and downstream is 26.5 meters. While the bottom width of the fishway is 4-5 meters, rest pools are set every 800 meters to better facilitate the fish to make their journey.

The construction of the fishway began in April 2017 and it had been put into use since the end of the same year.

Speaking of the intention of building a fishway, Mu Wanpeng, director of the Safety and Environmental Protection Department of the station, said that according to the environmental impact assessment of the project, there are 34 kinds of long-distance migratory fish in the area of the project. In order to meet the needs of these migratory fish and maintain the diversity of fish in the area, the company initiated the proposal to the Cambodian government to build the fishway.

"In order to verify the effectiveness of the fishway, the company has carried out regular inspections twice a month since the operation," Mu said. In addition, the company is currently planning to invite professional teams to carry out fishway observation and research projects.

Mu said that environmental protection work has always been the top priority of the project. The project has detailed regulations on atmospheric protection, production and domestic sewage treatment, soil and water conservation, etc. Fishway construction is only a part of it.

"We use underground buried sewage treatment facilities to effectively treat domestic sewage, and the treated wastewater can be recycled for gardening irrigation," Mu said.

The office and living area of the station is like a small garden with carpets of green grass, and diversified picturesque scenery.

Eng Phirong, director of the Stung Treng Provincial Department of Environment, said Lower Sesan II Hydropower Company has paid particular attention to environmental protection, complying with all requirements in the Environmental Impact Assessment paper.

"My colleagues and I have visited the hydropower station regularly to inspect the management of solid and liquid wastes and we found that the company has managed them very well," he said.

For the liquid waste, the firm has a reservoir to store it for treatment before releasing it into the river, Phirong said.