BANGKOK - Environmental researchers have found that 11 hydroelectric dams being constructed in the lower basin of the Mekong River will cost Cambodia $450 million in environmental damage while reaping similar havoc on neighboring Vietnam, the Phnom Penh Post reports Wednesday.

The Delta Study, a 30-month study conducted by the Ministry of Natural Resources and Environment for the Vietnamese government, concluded that the Chinese-constructed dams on the 4,350-kilometer transboundary river will disrupt fish migration and decrease fish stocks in the two Southeast Asian countries while causing salt intrusion into Vietnamese farmland.

"Biodiversity would be adversely impacted and fisheries, which have great national significance, would suffer very high declines in yields," said the Delta Study, which noted that Vietnam would similarly forfeit an estimated $760 million per year in depleted natural resources as dams will block the flow of nutrient-rich sediment to rice farms.

Environmental and social activists have condemned the mega-schemes to block the Lower Mekong mainstream with hydropower infrastructure for decades, calling on the Greater Mekong Subregion (GMS) countries of China, Laos, Myanmar, Thailand and Vietnam to protect the 20 million people who rely on the river for survival, according to the legal advocacy NGO Earth Rights International (ERI).

The Mekong River Commission (MRC), an intergovernmental advisory body on the dams, plans to release a further flagship study on the impact of the planned dams in 2017, according to the MRC website.

In 2010 the MRC issued a moratorium on dam-building in order to conduct environmental impact studies on the area.

Up to 80 million people globally have been forcibly removed from riverside areas to make way for dams, jeopardizing the food supplies and livelihoods of communities, according to the World Commission on Dams, as cited by ERI.