The scheme includes plans to build the Huai Tang reservoir in Lamphun.
Locals opposed to the reservoir staged a protest yesterday outside Chakkham Khanathon School in Muang district, where the hearing was held.
The reservoir, with a capacity of 9.2 million cubic metres, would be located at Ban Wang Luang in Lamphun's Ban Hong district.
The project comes under the government's 350-billion-baht water management scheme.
Despite the protests, organisers managed to wrap up the hearing within one day, giving each participant only three minutes to talk.
Environmental advocate Hannarong Yaowalers said this was not enough.
"It was nothing; it was like the locals just went to the school in the morning and returned home in the evening," he said.
Participants in the hearing had insufficient time to share their opinions and ask questions, he said.
He wondered whether the government would really listen to the dissenting voices.
In July, the Central Administrative Court delayed the water scheme, saying its projects are likely to have environmental impacts.
The court ordered the government to conduct public hearings before proceeding with any of the projects.
But Mr Hannarong claimed the organisers of the Huai Tang reservoir hearing tended to invite neutrals rather than people who would be affected by the project.
Participants were given documents which carried few project details, he said.
Decha Muyod, a Ban Wang Luang resident, said those who would be directly affected by the reservoir did not understand why the government has revived it.
The project had originally been cancelled by the Royal Irrigation Department in 1987 after it ruled the rock bed in the area was not strong enough to support the dam's structure.
At the hearing, locals said they had received almost no new information from the government.
They raised many questions in a peaceful way, but the organisers finally ended the meeting without giving all parties concerned the opportunity to speak and without answering all the questions that had been asked, Ban Wang Luang youth group leader Thanchira Thananonkhantachia said.
Supot Tovichakchaikul, secretary-general of the National Water and Flood Management Policy Office, insisted officials had clarified where the reservoir would be built, where evacuation areas would be situated in the event of a flood crisis, and what compensation would be paid to affected residents.
Mr Supot said authorities welcomed comments on the Huai Tang project and will submit these views to the government.
He was confident the other public hearings planned for the water management projects would proceed smoothly.
The government will hold hearings on other projects under the water management scheme between now and December. Projects under the scheme are planned for 36 provinces.