Parts of the river have reached their lowest levels in half a century
China has rejected claims that its dams on the Mekong River are to blame for record low water levels in downstream nations.
Speaking at a summit in Thailand, China's vice foreign minister said drought and not hydropower was to blame for the reduced river flow.
More than 60m people from Thailand, Laos, Cambodia and Vietnam depend on the Mekong River for their livelihoods.
Parts of the river are at their lowest levels in 50 years.
Further downstream drought, salt deposits and reduced soil nutrients are threatening food production in the rice bowls of Cambodia and Vietnam.
The leaders of Thailand, Cambodia, Laos and Vietnam all attended the Mekong River summit in the Thai resort of Hua Hin.
Addressing the summit, Thai Prime Minister Abhisit Vejjajiva warned that the river would not survive without good management.
"The Mekong River is being threatened by serious problems arising from both the unsustainable use of water and the effects of climate change," he said.
Activists have blamed Chinese dams for contributing to the drop in river flow and producing irreversible change to the river's ecology.
China has eight planned or existing dams on the mainstream river and says it wants more.
But Vice Foreign Minister Song Tao said the dams were not the problem.
"Statistics show that the recent drought that hit the whole river basin is attributable to the extreme dry weather, and the water level decline of the Mekong River has nothing to do with the hydropower development," he said.
He said that by regulating water flow, the dams could help with flood prevention and drought relief.
And he said that China had increased its information sharing in recent months - highlighting the provision since March of data from two hydrological stations to downstream nations.
Mr Abhisit said that the dialogue with China had been positive, and that he hoped information sharing would become "more systematic and more consistent" in the future.