VIENTIANE: Authorities in Xanasomboun district, Champasak province, have warned local residents not to use water from the Xedon River or to eat dead fish after a mass die-off raised serious health concerns.
The warning applies to Nadan, Nakharm and Khili villages, where large numbers of fish were found dead in the river from April 28 to May 2.
Residents have been instructed not to use the river water for daily activities or to feed aquatic animals to livestock, as the situation poses potential risks to both human and animal health.
An inspection by the Agriculture and Environment Department in Champasak province found that alkalinity levels in the river were significantly higher than the standard.
Preliminary results showed acidity (pH) measured at 11.30, 10.16, and 11.12—far exceeding the normal range of 5-9—indicating highly alkaline conditions. Electrical conductivity readings were recorded at 114, 131, and 131.
Oxygen requirement (DO/COD) levels were measured at 85.6, 152.6, and 95.3 litres, with Nakharm village showing particularly elevated values, while water temperatures ranged between 31.13, 34.99, and 33.02C.
The dead fish, now decomposing along riverbanks, have produced a strong odour and turned sections of the water murky, further alarming local communities.
Experts say such unusually high alkalinity may be linked to the presence of concentrated alkaline substances or industrial chemicals, including caustic soda (sodium hydroxide), calcium hydroxide (hydrated lime), or residues from bleaching processes or untreated industrial discharge.
Despite the absence of large-scale industrial activity in the affected areas, where most people rely on rice farming and small-scale agriculture, the source of contamination remains unclear.
Authorities stressed that the river water should not be used under any circumstances until further notice.
The Champasak provincial Department of Agriculture and Environment is continuing to coordinate with the Department of Livestock and Fisheries and other relevant sectors to collect samples of water and aquatic creatures for detailed analysis at a central research centre.
Further updates will be provided once the cause of the fish deaths has been confirmed. - Vientiane Times/ANN
