A public forum was held at the Wiang Pang Kham Municipal Office in the Mae Sai district of Chiang Rai province yesterday for stakeholders to exchange views and recommendations on cross-border contamination of the Sai River, which is increasingly threatening local livelihoods.
According to the Chiang Rai provincial administration, arsenic levels detected in the river were 28 times above safe limits, prompting authorities to issue warnings regarding tap water consumption, agriculture, and fisheries.
Aweera Pakkamart, director of the Environment and Pollution Control Office 1 in Chiang Mai, told the forum that tests on water and sediment samples from the Sai River consistently reveal hazardous substances exceeding safe standards.
Most recently, arsenic levels were measured at 0.284 mg/L, 28 times the safety limit, with contaminant levels continuing to rise, he noted.
His assessment aligns with observations by Pianporn Deetes, who stated that on-site inspections along the Thai-Myanmar border revealed some mines in Myanmar operating around the clock, with several running unregulated.
Dr. Suebsakun Kidnukorn, a lecturer at Mae Fah Luang University's School of Social Innovation, said at least 13 mining operations exist upstream along the Sai River.
He added that contaminated water and sediment have affected roughly 10,900 hectares of farmland, particularly rice fields and kitchen crops that rely heavily on the river.
Representatives from farming groups and local water users questioned how they could ensure crop safety and who would be held accountable if their yields were compromised.
An official from the Chiang Rai Land Development Office stated that staff had collected 52 soil and 92 water samples across two sub-districts for laboratory testing, with results expected soon.
Wittaya Masa, a fishery expert, noted that fish populations in the Sai River have dwindled significantly due to heavy water turbidity. Testing revealed trace amounts of arsenic in 19 fish species, as well as mercury and lead in 14 species each.
Addressing concerns over public tap water safety, the Mae Sai District Waterworks Authority stated that chemical treatment processes are currently being used as a short-term measure, while alternative water sources are being explored for long-term production.
To tackle the cross-border pollution crisis, forum participants urged the government to intervene directly and address the issue as a broader regional challenge requiring coordinated multilateral action.
