The relocation of the salt production industry from coastal provinces along the Gulf of Thailand to the Northeast in the 1970s caused the collapse of Maha Sarakham communities along the Siao River, a tributary of the Mun River.
Decades of intervention by the salt production industry — by pumping up underground saline water to produce salt and discharging wastewater into natural water sources — increased salinity in the Siao River, and led to soil subsidence and poisoning.
Villages in Maha Sarakham, Roi Et and Si Sa Ket protested against the industry in 1990, prompting the government to prohibit "irresponsible" salt production.
Some fear similar environmental problems could arise again after the government led by Gen Prayut Chan-o-cha last month granted a concession to Asean Potash Mining Public Co Ltd (APMC) to run a potash mine in Chaiyaphum.
The project has been delayed for decades by the economic slowdown and protests from residents over the likely impact on the environment.
Welcoming the project, governor Wichien Chantharanothai and local leaders said it could create 1,000 jobs.
"Everyone is happy with the mine," said Ban Tan village eight's headman Somchai Tamnaktan, 54. He said proudly his father was the first person to sell his land to the mine's operator decades ago.
The potash mine's environmental impact assessment was approved in July last year, and was followed by a trip to Germany of Industry Minister Chakramon Phasukavanich to study potash mining technology.
Gen Prayut then visited China, the largest fertiliser importer, raising fears among civic groups that the potash mine would soon be approved.
The APMC was established in 1991 with Asean members holding 29% of the total value, while Thailand's Finance Ministry holds 20% of the total value. The remaining 51% is held by the private sector.
The project is part of the "Asean Industrial Project" that originated from the Declaration of the Asean Accord, signed in 1976.
The mine is likely to run for 25 years producing 1.1 million tonnes of fertiliser a year. The first batch will hit the market by early 2018.
While Mr Somchai seems confident in the mine, some villagers were less enthusiastic.
A resident in Bamnet Narong, Sithi U-ten,54, said she was not sure if she would reap benefits from the mine, which will be located near her house.
A woman who identified herself as Plak, 82, said she opposed the mine because she was too old to be offered any work there.
Resident Saree Dongjorhor, 33, said he was worried about the environmental impacts.
Civic groups say the mine is likely to create a large volume of residue — 3.5 million tonnes of solid salt and 2 million cubic metres of saline wastewater each year.
Tanong Promma, APMC's CSR Department manager, said the mine would be run safely. The company bought 6,000 rai of land for a potash fertiliser factory, tailings pond and large buffer zone to prevent impacts on local people.
Residues will be taken from the mining area through seven-kilometre underground pipe to stockpile at a tailing pound surrounded by layers of trees.
All solid salt residues will return to the mine as backfill, said Mr Tanong. Salt water will be reused in the mining process.
"Saline wastewater will not leak into the environment. We'll implement a high-standard waste management system," he insisted. The industry minister also affirmed the safety of the mining project and said the country's potash imports will be reduced once the mine's output goes on the market.
Local groups have raised similar concerns about a potash mine in Udon Thani, opened by the Asia Pacific Potash Corporation in 1980, and since sold on to another company.
Eco-culture Study Group coordinator Lertsak Kamkongsak said he was worried that not all salt residues at the mine in that province would go into backfill. "Chloride compounds in salt have massive value for other industries, especially the petrochemical industry," he said.
This could lead to the development of a petrochemical complex in the region, and more potash mines springing up to cater to demand.
A mine without full backfill also could lead to subsidence of the ground by 1-2 centimetres a year and change the area's geography, said Mr Lertsak. The mining process would also consume large amounts of water from local sources. "Isan (the Northeast) is not ready to handle such large development projects," said Mr Lertsak.
"The government must come up with a clear strategy for salt extraction balancing economic benefits and sustainability. Promoting potassium fertiliser is contrary to the trend of chemical-free agriculture," he said.
If his predictions are correct, environmental problems stemming from the over-exploitation of salt will be repeated.