THE Mekong River Commission (MRC) has urged China and Lower Mekong countries to share water release plans as the river recorded sharp falls in water levels.
In Cambodia, the water levels have been declining steadily in several areas and was at worrying levels between the Jinghong hydropower station in China's Yunnan province and the Mekong Delta in Vietnam.
MRC's technical support director Dr Winai Wangpimool said if the flow pattern continues, it could have an impact on river transport, fish migration, agriculture and river weed collection.
"To help the Lower Mekong countries manage risks more effectively, we call on China and the Lower Mekong countries themselves to share their water release plans with us," he said.
The affected countries are Cambodia, Vietnam, Laos and Thailand.
According to Cambodia's AKP news, the statement said water levels had dropped "considerably" since the beginning of the year due to lower rainfall, flow changes upstream, hydropower operations in Mekong tributaries, and outflow restrictions from the Jinghong dam.
Dr Winai said there have been sudden rises and falls in water levels downstream of Jinghong and further down to Vientiane, Laos and it has been challenging for authorities and communities to prepare and respond.
The statement said monthly rainfall had also been consistently lower than average since November, falling by 25 per cent.
The MRC said the Mekong in Nakhon Phanom in northeast Thailand had recently turned aquamarine in colour due to the low flows, a slow drop in river sediments, and the presence of algae on the river bottom.
Meanwhile, MRC's chief environment management officer Dr So Nam said the blue-green water was "likely to spread to other stretches of the Mekong where low flows are experienced" – as happened in 2019.
He said potential impacts included changes in the productivity of the river with less food available for aquatic insects, invertebrates and small fishes.
This will reduce fish catches and threaten the livelihoods of local communities.
Normal conditions may be restored if large volumes of water are released from storage reservoirs in the Upper Mekong dams in China and tributary dams.
That would mobilise sediments and return the Mekong to its typically brown appearance, the statement said.
The MRC noted that China's Ministry of Water Resources notified the four Lower Mekong countries in January that the outflow from Jinghong would be restricted to 1,000 metres per second from Jan 5 to 24 due to maintenance of transmission lines but did not specify the river water levels.
The MRC recalled that China agreed last year to share year-round water level and rainfall data with the commission and pledged to notify any abnormal rise or fall in water levels or discharge.