Authorities are carefully monitoring the water quality in Klong Om Yai after a fire broke out on Monday afternoon at a chemical depot in Nakhon Pathom's Sam Phran district.
The fire at Prapakorn Oil Company's depot, where about 100,000 litres of lubricants and solvents were stored, began at 12.30pm. One person was injured by the blaze, which was brought under control around 4pm.
Police are still investigating the cause of the fire.
Director-general of the Pollution Control Department, Attapol Charoenchansa, said a special unit of environmental protection officers from Nakhon Pathom's Environment Office Region 5 had been dispatched to the area.
The team, he said, would assess the extent of chemical pollution in the area, particularly along Klong Om Yai, which runs beside the depot.
The water gates along Klong Om Yai and Klong Om Noi have been shut in order to prevent chemical runoff from flowing into the Tha Chin River, he added.
Mr Attapol said based on preliminary checks carried out after the incident, the water quality along Klong Om Yai, as well as air quality around the area, remained normal.