Environment advocates are voicing concerns over the Mekong River's deteriorating ecosystem, especially with more projects set to affect the waterway in the pipeline.
"If these so-called development projects continue, especially the construction of more dams, the Mekong will face a crisis," said Niwat Roi-kaeo, president of the Rak Chiang Khong Group, an environmental conservation collective based in Chiang Rai.
He was speaking at a seminar on the escalating problems facing the famous river.
Water in stretch of Thailand's northeastern provinces has turned a greenish-blue colour, he said, adding that while this strange phenomenon makes the river look beautiful it could be a sign of danger.
The phenomenon is described by environmental experts as the "hungry water effect" where a river flow with excess capacity to transport sediment erodes the bed and banks.
Upstream dams trap the sediment eroded from rocks and soils, leaving the river starved of its sediment load. The potential energy of this "hungry water" scours the river banks downstream, uprooting trees or riparian vegetation and damaging bridges and other engineering structures, according to Mr Niwat.
Hungry water erodes river banks below a dam more severely than the usual tide, said Chawalit Witthayanant, an expert on fish in the Mekong River.
"During the first few years of this phenomenon, fish become unusually abundant in the river; but not long after the stocks dwindle rapidly", he said.
Khampin Aksorn, the coordinator of a Mekong conservation group called "Network of People who love the Mekong", said in October villagers in Ban Tamui in Ubon Ratchathani were surprised to see a surge in fishing hauls along with clearer water in the river.
Eleven out of 28 Mekong dam projects have now been completed, the latest being Xayaburi dam in Laos, said Pianporn Deetes, Thailand campaign coordinator for International Rivers.
Much to Mekong conservationists' dismay, the government and the opposition have recently agreed to dust off a more than three-decade-old water diversion plan in Salween River, Yuam River, Moei River and Mekong River, she said.
This idea was abandoned years ago due to strong opposition driven by concerns over its impact on the rivers' ecosystems, said Mr Niwat.
All the same, the idea will this time face strong resistance from the local people and environmental activists alike, said Phongphipat Mibenchamat, a member of a Salween conservation group.
He likened the Mekong River to the rotten left arm of Thailand and Salween River to a right arm, which is now contracting the infection that destroyed the other limb.