[citation needed] In 1994, the Mekong Secretariat proposed in its report construction of the 3,300 megawatts (4,400,000 hp) hydroelectric structure blocking the entire river.

[1] In October 2006, the China Southern Power Grid Company signed a memorandum of understanding with Cambodia's Ministry of Industry, Mines and Energy at the Greater Mekong Subregion Expo in Nanning, China, to carry out a new feasibility study for the proposed dam with power generation capacity of 2,600 megawatts (3,500,000 hp) and for the alternative option of 465 megawatts (624,000 hp).

[2] In October 2016, Cambodia's Royal Group was authorised by the Cambodian Council of Ministers to sign a memorandum of understanding with the Cambodian Ministry of Mines and Energy to “thoroughly conduct” pre-feasibility, feasibility and social and environmental impact studies for three proposed dams: the Stung Treng, the Sekong (or Xekong) and the Sambor.

In the case of the first option, the dam will extend across the Mekong mainstream blocking the entire river flow.

Like other dams planned for the Mekong, the Sambor Dam has given rise to numerous social and environmental concerns from organizations including TERRA, International Rivers, WWF, and Save the Mekong about the potential impacts of the Sambor Hydropower Plant.

It is expected that the dam will have significant negative impacts on the Mekong's fisheries,[9] its hydrology and regional and national economies[8] According to the study of 1969, an estimated 5,120 people would be displaced by the project.

[1] A recent policy brief by the WorldFish Center and the Cambodian National Mekong Committee points to the serious impacts dams could have on Cambodia's fisheries and on the fisheries in Laos, Thailand, and Vietnam as a result of reduced river flows, and the 'flattening out' of the river's flood pulse.