The Ministry of Natural Resources and Environment says it will come up with a road map for marine debris management to deal with an estimated one million tonnes of garbage going into the sea every year.
It is part of the country's efforts to saving the marine ecological system, it said.
Wijarn Simachaya, the Environment Ministry's permanent secretary, said he has assigned the Department of Marine and Coastal Resources to survey the amount of marine debris and the impact of micro plastics on the marine ecological system in Thai waters.
The survey results will be used to assess measures to deal with the problem.
Plastic waste being dumped into the seas is a top concern in the world community as the practice poses severe threats to marine ecological systems.
He said the ministry is focusing on waste management in all 23 coastal provinces.
These provinces produce a combined 10 million tonnes of garbage per day, with half going into improper waste management systems.
It is estimated about one million tonnes of garbage gets dumped in the sea due to poor waste management, he said.
"The right way to deal with this is to figure out how to reduce waste at home. If we have less garbage on the mainland, we will also see less garbage in the sea," he told a seminar on "Public Participation on Marine Debris Management" organised by the Department of Marine and Coastal Resources.
According to an international study, 75% of garbage in the sea comes from 10 main rivers in the world -- if the amount of garbage in those rivers is reduced by 50%, marine debris would decrease by 75%.
Thailand is considered one of the world's worst garbage polluters of the sea, after China, Indonesia, the Philippines, Vietnam and Sri Lanka.
The study also found some marine animals are being endangered because marine debris is the second biggest cause of death among them.
Of the total coastal garbage, plastic bags make up 15%, straw accounts for seven percent, cigarette butts are five percent.
Mr Wijarn pointed to the waste management problem in Koh Samui in Surat Thani province, saying tourists and residents produce around 170 tonnes of waste per day, leaving an accumulated 300,000 tonnes of garbage in need of proper disposal.
He added it is a challenging issue to figure out how to deal with the huge piles of waste that are getting bigger every day, saying the ministry plans to enforce stronger control over plastic consumption on islands or even ban the use of plastic on certain islands to limit the amount of garbage in the sea.
Thailand is set to host the Asean regional meeting on marine debris management in November, where it will encourage all Asean members to enforce concrete measures to deal with the problem.
Thon Thamrongnawasawat, a marine expert and member of the committee on reform that works on environment and natural resources, said various agencies will work together to draft the road map. It will include a plan to reduce plastic consumption, carrying out area-based management of marine debris, and developing equipment to improve tools for collecting garbage in the sea. It should be completed by this month.
He said the road map will be a guideline for agencies to take action on marine garbage management with close cooperation from local administrative organisations, adding that garbage is a significant cause of death to marine life and the issue requires urgent action.
According to the department, 150 sea turtles, 100 whales and dolphins and 12 dugongs die each year, half of which die from eating plastic bags.