Thrice in total , the floodgates of Cheruthoni had to be opened ; twice during the northeast monsoon ( October to December ) of 1981 and 1992 and once during the 2018 Kerala floods . The first time was in 1981 ( when the shutters were repeatedly opened and shut between 29 October and 13 November ) and the second time was in 1992 ( when they were kept open for 12 days from 12 to 23 October ) and recently during the great flood of 2018 from August 9th 2018 to September 7th 2018 , all 5 shutters were opened while all 14 districts of kerala were put under Red Alert with heavy disaster creating destruction all over kerala . On the first 2 occasions , the water level in the dam touched the brim only when the storage built up during the southwest monsoon ( June to September ) was augmented by the inflow received immediately afterwards following heavy downpour early in the northeast monsoon . On 9 August 2018 , after a gap of 26 years , owing to continuous downpour of the southwest monsoon , the floodgates of dam in Idukki was opened . This was the first instance of water being released from the dam during the southwest monsoon season and also the first time in history when all 5 shutters of the dam were opened since it was commissioned in 1976
2018 Kerala floods
2018 Kerala floods
Cheruthoni Dam