The Department of Irrigation says 13 reservoirs are spilling over owing to the incessant rain experienced over the island during the past few hours.
The Department said the water levels of reservoirs in the Anuradhapura, Vavuniya and Puttalam districts have significantly risen.
The Department also requested residents of low-lying areas of the Malwathu Oya to remain vigilant of rising water levels.
Director of the Water Management Unit of the Department Engineer B Abeysiriwardene said ten spill gates of the Rajanganaya Reservoir were opened four feet, the Angamuwa and Mahawilachchiya Reservoirs and 20 other tanks are spilling over.
Abeysiriwardene said Anuradhapura during the past 24-hours experienced 225mm of rainfall.
He urged residents of Vavuniya, Puttalam, and Kurunegala to remain cautious owing to the rising water levels in the event rains continue tonight as well.
He added 20 spill gates of the Thabbowa Reservoir while four spill gates of the Deduru Oya in the Puttalam District have been opened owing to the rising water levels and therefore stated that flooding has been reported in several parts of Puttalam.