Water levels in the northern Mekong River are at record-low levels, posing a threat to water supply, navigation and irrigation along a stretch of water that is home to millions, a regional official said.
Northern Thailand, northern Laos and southern China have all been affected, Jeremy Bird, chief executive officer of the Mekong River Commission (MRC) secretariat, told AFP.
"The flows are much lower than we've got records on in the last 20 years," said Bird, whose inter-governmental body deals with all Mekong River-related activities including fisheries, agriculture and flood management.
"Now what we're seeing is these flows are reducing even more," Bird said from Laos on Thursday.
More than 60 million people in the lower Mekong basin depend on the river system for food, transport and economic activity, the MRC says, adding that it is home to the world's most valuable inland fishery.
Bird said 21 cargo boats have reportedly been stranded because of the shallow river water in southern China.
A regional drought has caused the water to drop, the MRC said.
"Severe drought will have an impact on agriculture, food security, access to clean water and river transport and will affect the economic development of people already facing serious poverty," it said in a statement.
"The northern provinces are amongst the poorest areas for both Lao PDR and Thailand."
River tour operators have stopped offering services on the river between the Laotian tourist centre of Luang Prabang and Huay Xai on the Thai border, the MRC said.
Officials in Laos have started advising people to reduce water consumption.
Bird said it is difficult to say whether global warming is responsible but the wet season in Vientiane last year was one of the worst on record, and was followed by much lower than average rain late in 2009 and early this year.
As a result, there has been very low water flow in the Mekong's tributaries.
"The rainfall in China is also extremely low," Bird said.
Thai non-governmental groups believe the unusually low levels are caused by Chinese dams, according to reports in the Bangkok Post.
There are eight existing or planned dams on the mainstream Mekong in China, the MRC has said.
"It's difficult for us to say categorically that there's no link" between the low water levels and those dams, Bird said.
But he added it would not be normal for dams to be filled during the dry season.
The Nation newspaper in Bangkok reported that Thailand would ask the MRC to negotiate with China for the release of more water from its Mekong dams to alleviate downstream drought.
Bird said the commission has not yet received any formal request from Thailand. If it does, the MRC would discuss with China the possibility of releasing water.
"This is one area where the dams upstream would actually be beneficial," he said, because once the hydropower projects are in service they should lead to 30-40 percent more dry-season water flow.
China and Myanmar are dialogue partners with the MRC which groups Thailand, Laos, Vietnam and Cambodia.
MRC data show that water levels on the Mekong in Cambodia are not as low as in the north, which Bird said is explained by factors such as different regional rainfall systems.
For the north, the problem is only set to get worse.
"The flows will probably continue to reduce for another month," Bird said.
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