Large-scale gold mining in territory controlled by the United Wa State Army in Shan State was the primary cause of unprecedented mud damage during recent flooding in the Thai border town of Mae Sai, the Shan Human Rights Foundation (SHRF) reported on Thursday.
Citing a study last month by Thailand’s Department of Natural Resources, the foundation said gold mines on the Sai River operated by the UWSA in eastern Mong Hsat blanketed most of Mae Sai district, Chiang Rai province, in a sea of toxic mud.
Conducted in October, the study tested flood sediment from the Sai riverbank and found high levels of heavy metals associated with mining, particularly arsenic, nickel and zinc. Levels of zinc in test samples were 18 times higher than the safe standard. Satellite images from the study highlighted gold mining areas in Mong Hsat upstream of Mae Sai.
The Sai River periodically floods Mae Sai and the adjoining border town of Tachilek in Myanmar. However, this year the floods contained significantly more mud, which contaminated houses, businesses and land in Mae Sai, necessitating a 45-day cleanup campaign.
“The study focused on sediment and floodwater that entered the town during the floods,” Ying Leng Harn, a spokesperson for the SHRF, told The Irrawaddy.
The foundation said that mining in Mong Hsat was taking a severe toll on the local environment, with toxic waste polluting rivers and affecting the health of residents in Shan State and over the border in Thailand.
“The water is contaminated with chemicals from mining, affecting public health. Previously, it mostly affected Shan State, damaging crops and causing women to miscarry. So far, it has triggered only flooding. But in future, it could cause widespread landslides, mudslides, and toxic soil,” Ying Leng Harn said.
The SHRF report states that gold mining in eastern Mong Hsat has rapidly expanded over the past two years near Mong Karn and Na Yao villages under the control of the UWSA, and Mae Jok village under a regime-aligned militia.
The mining in Mong Karn and Na Yao began in late 2022 and is taking place directly alongside the Sai River. The hills beside the river have been flattened and turned into vast leaching ponds where toxic chemicals including cyanide are used to separate the gold, the report said.
The mining in Mae Jok, which began in late 2021, is taking place in the hills close to the Thai border, with run-off from the mines flowing into a stream that joins the Sai River above Mong Karn. The Mae Jok area is controlled by a local Lahu militia aligned with the military regime, according to the report.
Further downstream, south of Mong Hsat town, seven Chinese companies linked to the UWSA have been mining gold at several sites beside the Kok River since last year. Toxic residues from the mining flow directly into the river, only about 30 kilometers from the Thai border.
The Sai and Kok rivers are tributaries of the Mekong, Southeast Asia’s largest river and a vital lifeline for an estimated 60 million people who rely on it for water and food.
