The Supreme Court will hand down a ruling Monday in a long-standing legal battle between a bankrupt company and the lead-contaminated Klity Creek community in Kanchanaburi's Thong Pha Phum district.
Surapong Kongchantuk, director of the Karen Studies and Development Centre, said the ruling will set a precedent on community rights involving the clean-up and rehabilitation effort.
In their appeal to the Supreme Court, the Karen villagers insisted they can file a lawsuit seeking to force Lead Concentrates (Thailand), the company accused of contaminating their water resource, to clean up and rehabilitate the area, he said.
The Appeal Court, while awarding 36 million baht in compensation to the villagers, dismissed a separate complaint seeking to force the company to rehabilitate the creek, he said.
"The court argued it was the Pollution Control Department's job to force the company to rehabilitate. So the villagers appealed and argued for their rights. This is a crucial point we expect in the ruling," he said.
According to Mr Surapol, the mining company claims in its appeal that the leak was accidental and the company's executives should not be held responsible for the damage caused to the environment.
Klity Creek is one of the country's biggest environment cases.
The lead contamination of Klity Creek was exposed in 1998 when the Department of Mineral Resources ordered the closure of Lead Concentrates. The creek was contaminated by water illegally discharged from a nearby lead factory.
Three lawsuits were lodged in connection with the case and two of them reached a conclusion.
In January 2013, the Supreme Administrative Court ordered the PCD to pay nearly 4 million baht in compensation to 22 Karen villagers over lead contamination.
The court found the PCD's handling of the Klity Creek incident reflected the lack of a proper emergency response plan, which caused harmful pollution to spread into the environment and affect nearby residents.
In July 2015, the Supreme Court's Environment Division ordered the mining company to pay 20.2 million baht in compensation to eight villagers affected by the lead contamination.
Monday's ruling will conclude the third lawsuit in which a group of 151 Karen villagers demanded over one billion baht in compensation for the damage.
In December 2010, the provincial court ordered the mining company to pay 36 million baht in compensation and the Appeal Court upheld the decision in February 2012.