{"id":47765,"date":"2026-09-22T15:41:25","date_gmt":"2026-09-22T08:41:25","guid":{"rendered":"https:\/\/transbordernews.in.th\/home\/?p=47765"},"modified":"2026-09-22T15:41:27","modified_gmt":"2026-09-22T08:41:27","slug":"sai-river-pollution-crisis-deepens-as-arsenic-hits-28-times-safety-limit","status":"publish","type":"post","link":"https:\/\/transbordernews.in.th\/home\/?p=47765","title":{"rendered":"Sai River pollution crisis deepens as arsenic hits 28 times safety limit"},"content":{"rendered":"\n

Experts urge authorities to issue immediate warnings as pollution agency confirms results; MP questions effectiveness of Thailand-Myanmar cooperation framework.<\/strong><\/p>\n\n\n

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CHIANG RAI: Toxic contamination in the Sai River along the Thai-Myanmar border has reached its highest recorded levels, with arsenic detected at more than 28 times the standard and lead at more than five times the limit, prompting warnings over risks to agriculture and communities dependent on the river.<\/p>\n\n\n\n

The Pollution Control Department (PCD), in its 22nd round of water-quality monitoring, found arsenic at 0.284 milligrammes per litre, compared with the standard of 0.01 mg\/L, and lead at 0.266 mg\/L against the 0.05 mg\/L standard.<\/p>\n\n\n\n

The samples were collected in August. The results represent the highest concentrations recorded since monitoring began in 2025.<\/p>\n\n\n\n

Prasert Jitpleecheep, deputy governor of Chiang Rai, told Transborder News that the sharp increase was unusual and should be independently verified before authorities introduce measures that could have wide economic and social consequences.<\/p>\n\n\n\n

He questioned why contamination had risen so dramatically in the Sai River while results downstream in the Ruak River did not show a comparable increase, despite the two rivers being hydrologically connected.<\/p>\n\n\n\n

Mr Prasert said the province had nevertheless issued precautionary warnings and contacted the Provincial Waterworks Authority (PWA) to strengthen monitoring.<\/p>\n\n\n\n

The province is also seeking funding in the 2027 fiscal year for 17 real-time water-quality monitoring stations. The system would allow irrigation authorities to respond rapidly when contamination spikes, including closing irrigation gates to prevent polluted water entering farmland.<\/p>\n\n\n\n

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PCD stands by results<\/strong><\/p>\n\n\n\n

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Aweera Pakamat, director of the PCD’s Environment and Pollution Control Office 1 in Chiang Mai, said the agency stood by its laboratory findings.<\/p>\n\n\n\n

He said sampling coincided with severe flooding in Myanmar on Aug 3-7. Turbidity in the Sai River rose from around 600 units during previous monitoring rounds to nearly 3,900, an increase of six to seven times.<\/p>\n\n\n\n

The dramatic rise in suspended sediment corresponded with the unusually high arsenic and lead concentrations, he said.<\/p>\n\n\n\n

The PCD subjected the samples to repeated laboratory analysis beyond normal verification procedures and confirmed the results, Mr Aweera said.<\/p>\n\n\n\n

The agency’s monitoring data indicate that the Sai has consistently recorded higher heavy-metal contamination than the Kok, Ruak and Mekong rivers in the area.<\/p>\n\n\n\n

Residents have been advised not to use untreated river water directly.<\/p>\n\n\n\n

The PCD has also asked the PWA to intensify surveillance. The water utility has said treated tap water remains safe.<\/p>\n\n\n\n

Agriculture, however, remains a major concern because existing irrigation infrastructure lacks adequate sedimentation systems.<\/p>\n\n\n\n

Farmers have been advised to suspend pumping from the Sai River during periods of high turbidity, particularly for crop fields and aquaculture ponds. Where river water is unavoidable, it should first be held in settling ponds to reduce contaminated sediment, the PCD said.<\/p>\n\n\n\n

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Scientist urges faster warnings<\/strong><\/p>\n\n\n\n

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Asst Prof Wan Wiriya, assistant head of Chiang Mai University’s Environmental Science Research Centre, said independent laboratory and community monitoring, including field test kits, had produced findings consistent with the PCD results.<\/p>\n\n\n\n

Tests had detected arsenic at roughly 28-30 times the standard, she said.<\/p>\n\n\n\n

Delaying public warnings while waiting for further confirmation could undermine risk prevention because contaminant concentrations in rivers change rapidly and become diluted over time.<\/p>\n\n\n\n

\u201cRisk communication cannot end with reporting numbers,\u201d she said. \u201cPeople need to know what they should do next.\u201d<\/p>\n\n\n\n

Dr Wan called for universities, independent researchers and citizen scientists to participate in parallel monitoring alongside government agencies.<\/p>\n\n\n\n

She said the current monitoring schedule was too infrequent to function effectively as a pollution early-warning system. By the time laboratory results become available, contaminated water may already have been pumped into farmland.<\/p>\n\n\n\n

She proposed combining continuous real-time monitoring with community test kits. Sudden increases in indicators such as turbidity could trigger immediate field testing, allowing local authorities to halt irrigation pumping until contamination falls to safer levels.<\/p>\n\n\n\n

Chiang Mai University is also procuring a high-resolution mass spectrometry system, expected to become operational by the end of the year, to strengthen laboratory capacity and support internationally recognised testing standards.<\/p>\n\n\n\n

On Sept 26, the US Embassy and Consulate General in Chiang Mai are scheduled to provide 120 field test kits for water and soil testing in Mae Ai district for distribution to agencies and academic institutions, she said.<\/p>\n\n\n\n

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Irrigation agency lacks real-time data<\/strong><\/p>\n\n\n\n

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Thaweechai Khotrakul, director of the Chiang Rai Irrigation Project, said his agency currently lacks both specialised chemical-pollution expertise and an advanced laboratory.<\/p>\n\n\n\n

Water samples must be sent to other agencies for analysis, meaning irrigation officials cannot determine heavy-metal concentrations in real time.<\/p>\n\n\n\n

\u201cIf we had an early-warning system showing where contamination was moving and when concentrations were high, we could immediately close irrigation gates,\u201d he said.<\/p>\n\n\n\n

The gates could then be reopened once monitoring confirmed that contamination had fallen to safe levels.<\/p>\n\n\n\n

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MP criticises government response<\/p>\n\n\n\n

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Phattharapong Leelaphat, a Chiang Mai MP from the People’s Party and chairman of a parliamentary subcommittee studying transboundary water pollution, criticised the government’s handling of the crisis.<\/p>\n\n\n\n

He said the record contamination coincided with heavy rainfall in the Sai River headwaters and alleged that mining areas across the border had exposed soil and contaminated waste to heavy rain, allowing sediment and pollutants to wash into the river.<\/p>\n\n\n\n

Mr Phattharapong also criticised progress under the recent Thailand-Myanmar cooperation framework on transboundary water quality, arguing that contamination had continued despite bilateral discussions.<\/p>\n\n\n\n

He said affected communities could consider administrative court action over what they regard as inadequate government protection, drawing parallels with earlier litigation over PM2.5 air pollution.<\/p>\n\n\n\n

For immediate risk reduction, he advised residents to diversify their food sources rather than repeatedly consuming fish or produce from potentially contaminated areas.<\/p>\n\n\n\n

He also called on local authorities to regularly disclose test results for village water supplies and groundwater, and urged the Mae Sai branch of the PWA to publish results for both raw Sai River water and treated tap water.<\/p>\n\n\n\n

The latest findings have intensified concern over a pollution crisis that has affected rivers flowing from Myanmar into northern Thailand since 2025, while local communities continue to call for more frequent testing, transparent public information and action to address contamination at its source.<\/p>\n\n\n\n

This is a translation of original Thai news reports<\/p>\n\n\n\n

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