The controversial dam was built in 1994, but its construction was met with vocal objections from residents.
Paijit Silalak, leader of Ban Pak Mun Wisdom Centre, said villagers who had led protests against the dams received notices from police last week asking them to report to Boontarik police station
After learning they would be charged for treason, none of the villagers went to the police station, he said.
Mr Paijit said the villagers are in hiding for fear of being arrested.
He said the police charges were based on a complaint filed against the group by the Electricity Generating Authority of Thailand (Egat) in 2000. The complaint accused the villagers of obstructing the dam project.
The police have claimed the protests, which were led by 14 core leaders, were unconstitutional. Rallies organised by the villagers at the time were also illegal, the police said.
Warrants for the 14 arrests are due to expire on May 19, next year. Four of the villagers are dead. One has been acquitted by the court and another is being prosecuted.
Mr Paijit said the Pak Mun Dam affair was considered a political case, and villagers had in the past relied on help from politicians in communicating with police.
Now, however, the villagers have had trouble securing the help of politicians due to the political conflict in Bangkok.
As well as the pending legal case, villagers have also had problems trying to settle their conflict with Egat concerning the opening of the dam’s sluice gates.
During the administration of the Democrat-led government, it was agreed that a panel would be set up to supervise opening the sluice gates.
It was agreed that the gates would be opened all-year-round for five years to address villagers’ concerns over the dam’s ecological impact on the Mun river.
The government also agreed to compensate villagers affected by the dam project. It said the payments would be backdated for 20 years.
Mr Paijit said that the panel was never formed.
Yingluck Shinawatra’s government agreed to carry on with the Democrat’s decision, but dissolved the Lower House before forming the panel.
“The special panel should have been set up in May last year. But it seems that our hopes have completely vanished," he said.