The authorities said that five of the shutters were raised by 60 cms while the remaining four shutters were raised by 30 cms to release the excess water into the Periyar river.

Although Tamil Nadu authorities resumed tunnel discharge on Sunday evening, in addition to raising one shutter apart from shutter V3 which is kept open since November 23, water levels rose above 141.9 ft by Monday night.

Following heavy rainfall through Monday night, water levels had risen forcing the authorities to release the surplus water.

People living downstream have been alerted about the development and advised to leave the area.

The British-era masonry gravity dam is managed by the Tamil Nadu government although it is geographically situated in Kerala. The dam is at the centre of a row between the states, with Kerala keen on constructing a new dam while Tamil Nadu opposing the proposal.