Authorities in Kratie and Stung Treng provinces on Thursday said that they were investigating an unusual change of color in the Mekong River to a muddy, dark brown that was unnatural for this time of the year and was worrying residents.
Since the beginning of this year, Kratie’s department of water resources and meteorology said mud and possibly other dirt has been polluting the Mekong River and has caused the its color to change from relatively clear to dark brown.
“It has never been this muddy before,” said the department’s director, Heng Rothmonida, adding that his department had taken samples to help determine whether it was simply mud causing the change or possibly pollution from upstream development projects.
“We are still investigating and trying to find the reason as to why the Mekong River is so muddy,” he said.
About two weeks ago, the river started to get darker, and got “really dark” last week, Mr. Rothmonida said, adding that residents were worried that whatever was causing the color could affect the fisheries as well as the nearby Irrawaddy dolphin pools.
Tuy Chandara, Stung Treng’s deputy director of the provincial department of water resources and meteorology, said that his department was also concerned about the river’s color.
“I have never seen the water this muddy before during the dry season, and we do not know the reason for it yet,” Mr. Chandara said.
Both provincial departments are investigating the nature of the sediment, and whether it could be a form of pollution.
The immediate concern, Mr. Chandara and Mr. Rothmonida said, is the future of the critically endangered Irrawaddy dolphin.
According to the WWF, fewer than 100 of the highly sensitive freshwater dolphins live in a total of nine pools in Kratie and Stung Treng provinces.
WWF’s conservation area project manager in Kratie province, Horn Chandet, also said that his department would investigate the change of color and determine whether it could affect the dolphins.
“If it’s pollution, it will have a bad effect on the dolphins. They are very sensitive to changes, and pollution can kill them,” Mr. Chandet said, adding that a biopsy had been taken from a dolphin that had died last Friday.
Ame Trandem, Southeast Asia program director for advocacy group International Rivers, said that sediment from last month’s Mekong flooding in Thailand, Vietnam and China could have reached northern Cambodia by now.
Within less than a week, the water level of the Mekong rose by more than one meter in mid-December, according to the Mekong River Commission (MRC).
“The MRC’s past records show that there has not been such a sudden peak of this scale in December in the last 50 years,” the intergovernmental agency said on its website.