The search began after the alarm was by Chaweewan Kongkaew, who checked with local hospitals for her long-term partner Pharit Daorueang, 40, who had failed to come home from his fishing trip.
Police are assisting with the search, despite the official requirement for a person to be missing 24 hours before police can receive a missing person report.
Ms Chaweewan explained to police that Mr Pornthip went fishing at the lake at about 3pm yesterday.
When the search team arrived at the reservoir, Mr Pornthip’s motorbike was still parked there, with three candles and incense in place for prayer beside the motorbike. His shoes and fishing gear were by the reservoir’s edge
Divers are now searching the reservoir which is up to 15 metres deep, noted Capt Eakkasak Kwanwan of the Thalang Police.