People are now reluctant to buy fish caught in the Kok River, due to reports that the river is contaminated with arsenic and other heavy metals, according to Somkiat Kuenchiangsa, President of the Living River Siam Association.
Authorities in Chiang Mai and Chiang Rai, through which the Kok River flows, have advised people to avoid using the water, following lab test results indicating that the water is contaminated.
Sediment samples, collected on March 31 and April 1 from the Kok River in Chiang Rai’s Muang and Chiang Mai’s Mae Ai districts, were found to contain arsenic levels exceeding safety standards.
Tests also detected arsenic at an average concentration of 0.13 mg/kg in fish from the river. This is, however, below the safety threshold of 2mg/kg and considered safe for consumption.
Fishermen have, though, continued to find fish with visible abnormalities. These cases are still under investigation, to determine whether they are linked to the contamination.
Similar abnormalities have been found in fish from the Mekong River, a major regional waterway, raising additional concerns about potential contamination as well, Somkiat said.
He voiced concern that fish in the Mekong are now beginning to migrate upstream, to spawn in tributaries as the rainy season approaches.
“This pollution could have a severe and widespread impact,” he warned.
The detection of toxic substances in the Kok River is very alarming, especially since fish populations were already in decline. The presence of these toxins could further disrupt their reproduction and growth.
The pollution is suspected to come from large-scale mining operations in Myanmar, reportedly backed by Chinese investors, which are believed to be discharging polluted waste water into the river untreated.
The contamination has spread to the Sai River, affecting communities in Chiang Mai province as well. Other substances found in sediment samples include nickel, chromium and cyanide.
To address the issue, Somkiat urges the Thai government to initiate a dialogue between Myanmar, ethnic armed groups and China and has proposed that the ultimate solution may be to halt mining operations in Myanmar altogether.
