Chiang Mai: The Pollution Control Department inspected the water quality in the Mae Kok River in Chiang Mai Province and found that it was deteriorating due to several factors. Heavy metals were also found to exceed the standard, which may be related to mining.
According to Thai News Agency, Mr. Awira Phakmatra, Director of the Office of Environmental and Pollution Control 1 (OEC1) in Chiang Mai, Department of Pollution Control, stated that water quality in the Mae Kok River Basin was monitored by collecting surface water samples for analysis. The Kok River in Mae Ai District is unusually turbid, raising concerns among locals about water consumption and activities during the summer.
Three checkpoints were established to monitor the situation: Checkpoint 1 (Mae Ai 01) on the Thai-Myanmar border at Ban Kaeng Tum, Checkpoint 2 (Mae Ai 02) at the Mae Na Wang-Tha Ton Friendship Bridge, and Checkpoint 3 (Mae Ai 03) at Ban Pha Tai. The results indicated that the Kok River water quality is in the 'deteriorated' category at all three points, with significant parameters exceeding the standard levels.
Key parameters affecting water quality include organic matter contamination, total coliform bacteria, and fecal coliform bacteria, all exceeding standards at the three checkpoints. This indicates high pollution levels due to untreated wastewater discharge and contamination from warm-blooded animal feces. Additionally, ammonia levels at Mae Ai 03 exceeded the standard due to protein decomposition and plant and animal remains.
The turbidity levels were particularly high, with the first checkpoint near the Thai-Myanmar border recording 988 NTU, and the second and third checkpoints showing 171 and 139 NTU, respectively. Standard values should not exceed 100 NTU to ensure the survival of aquatic life.
Tests revealed that heavy metals, specifically lead and arsenic, exceeded the standards. Lead levels were notably high at the border, measuring 0.076 mg/L, surpassing the standard of 0.05 mg/L. Lead contamination is often linked to factory and mining wastewater discharge. Arsenic levels exceeded standards at all three checkpoints, with values of 0.026, 0.012, and 0.013 mg/L, surpassing the 0.01 mg/L standard. Its presence is likely associated with gold mining upstream in Myanmar.
Mr. Awira highlighted that arsenic contamination in the Kok River is probably linked to gold mining activities upstream, as gold ore naturally contains arsenic. The Pollution Control Department has informed the Chiang Mai governor about the findings to caution the public against using or coming into direct contact with the river water. Relevant agencies are urged to inspect and implement measures to address and prevent long-term pollution issues.