The government plans to build check dams on northern rivers to filter out hazardous pollutants from mining operations in neighbouring Myanmar, Deputy Prime Minister Phumtham Wechayachai said on Wednesday.
Water sampling has detected unsafe levels of heavy metals, especially arsenic and lead, in the Kok, Sai and Mekong rivers in Chang Mai and Chiang Rai provinces.
The contamination came from mines near the catchment areas in Myanmar, Mr Phumtham, who is also defence minister, said.
According to Myanmar officials, the catchment areas were probably under the control of rebellious ethnic groups. Thailand, therefore, needed to take action to protect itself, he said.
The Department of Water Resources was designing the dams, which would filter out hazardous substances that could later be disposed of, he said.
“The dams are in the design process. There would be problems with any negotiations [to reduce the pollution] because the root cause of the problem is not in Thailand. The best thing we can do is to protect ourselves,” Mr Phumtham said.
He admitted that tests on surface water samples showed unsafe levels of contamination at many locations. “But that does not pose any immediate danger,” the deputy prime minister said.
The Pollution Control Department and the Department of Health reported that it was a long-term problem and not an immediate issue.
“If we do nothing, there will be problems in the future. But I confirm that there is no danger at present,” Mr Phumtham said.
“Local people are citizens of Thailand and important resources. The government will not let the people suffer from this hazard. It is duty-bound to protect them,” the deputy prime minster said.
The Kok and Sai rivers have their headwaters in Myanmar. The Sai River enters Thailand in Mae Sai district of Chiang Rai and joins the Mekong River in Chiang Saen district of Chiang Rai.
The Kok river enters Thailand in Mae Ai district of Chiang Mai and also flows into the Mekong River in Chiang Saen district of Chiang Rai.