Conservationists have slammed veteran politician Somsak Thepsuthin for his call to revive the Kaeng Sua Ten dam project on the Yom River.
The controversial plan has drawn resistance for over two decades and was branded unfeasible by authorities recently.
The Forum of the Poor, one of the country's oldest grassroots movements, and veteran conservationists alike criticised Mr Somsak, a former MP from Sukhothai.
Mr Somsak floated the idea this week and tried to drum up support to revive the project ahead of a visit by Prime Minister Prayut Chan-o-cha to Sukhothai on Dec 25-26 for a mobile cabinet meeting.
Mr Somsak also wrote on his Facebook page that his province should get not less than five billion baht from the PM's visit. It is expected that Mr Somsak will talk about the project during the visit.
The Forum of the Poor later denouncing Mr Somsak, calling him an "antiquated politician."
"The case [of Kaeng Sua Ten dam] has been closed. The Royal Irrigation Department has already returned the fund for studying the environmental impact assessment of the project, the statement said.
"A panel appointed by this government has already concluded that the dam project is not feasible and proposed an alternative plan to build small and medium sized reservoirs and dams along the Yom river course. We demand Mr Somsak stop creating divisions among villagers," it added.
The dam project was initiated more than two decades ago and has drawn opposition from the public ever since. The construction requires the clearance of large swathes of teak trees from a national park.
Hannarong Yaowalers, a veteran activist and a former member of the National Reform Council, said Mr Somsak is driven by a political agenda.
"The fate of this project is sealed. What is the purpose of the mobile cabinet. Is it a means to listen to the real needs of people or is it a platform for politicians to revive a project and canvas political support."
Chainarong Srettachuea, a lecturer at Mahasarakham University, said the best way to solve floods along the Yom River was not to build large a dam in a national park in mountainous areas.
"The Kaeng Sua Ten project would only worsen flooding and create drought as upstream watershed forests that help generate and absorb water would be destroyed."
He said water should be managed through a nature-based approach, proper town planning and land use management.
The area around the Yom River, where Sukhothai, Uttaradit and Nakhon Sawan is located is largely a flood plain where water from upstream runs into causing inundation. Mr Chainarong said one of the reasons for perennial floods is poor town planning and land use.
"Flood plains and wetlands that should be used for draining have been used to build Sukhothai airport, buildings and roads," he said.