Vietnam has officially asked Laos to delay the construction of a controversial dam on the lower Mekong River for ten years to have more complete studies on its ramifications, a local official said Monday.

All the documents and statistics about Xayaburi dam’s construction that Laos sent to Vietnam aren’t complete without factual estimates, Minister of Natural Resources and Environment Pham Khoi Nguyen said.

Nguyen, also the chairman of Vietnam National Mekong Committee, stressed that the effects of the first proposed dam on the lower Mekong River, for example, on Vietnam’s Mekong Delta were yet to be studied completely.

“There are another 11 dams planned on the Mekong river’s mainstream. If all are built without complete estimates on their influences, the Mekong Delta will be greatly affected,” the official said.

“So, we are very concerned about the construction of dams on the river’s mainstream.”

According to Nguyen, initial studies showed that dams on the river will constrict water flow on the Mekong Delta, and silt loss will be astronomical.

It was estimated that the amount of silt will decrease from 26 million tons a year to 7 million tons, while the amount of fish will go down as well, affecting the local biodiversity, he said.

Vietnam is also asking Laos to provide it with more documents for further studies, and asking international organizations to cooperate with it in studying as well, according to Nguyen.

He said the $3.8-billion dollar project, financed by Thailand, will be considered again at a meeting among environment ministers from Vietnam, Laos, Cambodia and Thailand this November.

On April 19, the river’s four stakeholders failed to reach a consensus on the project that has drawn criticism from international experts who said its environmental influences would be much greater than estimated in studies conducted by its investor.

Under an agreement between the Mekong countries in 1995, any hydropower plant on the river needs consultations before being built.