The Pollution Control Department is to take legal action against ethanol production plants in Ratchaburi suspected of discharging effluence into Mae Klong river resulting in mass death of giant stingrays.
Department chief Vijarn Simachaya said on Friday that laboratorial tests of samples of the water taken from the river show ammonia density 18 times higher than normal which pose great danger to fish and other lives in the river.
He pointed out that it was high tide during the early period of October preventing water from the river to flow into the sea. This has resulted in the discharges from ethanol production plants to sink and deposit at the bottom of the river.
Meanwhile, Dr Nanthrika Sansue, director of fish diseases, said that the main cause of the death of giant stingrays was cyanide.
Officials from the Pollution Control Department will next week lodge complaint with police in Ratchaburi against ethanol production factories.