Inc., Canada,[1][2] The water impounded by these three dams of Idukki, Cheruthoni & Kulamavu has formed a single reservoir spread over 60 km2 on a height of 2300 ft above Mean Sea Level.

Located at Moolamattom, it is the biggest underground power station in India and the pressure shaft is the largest in the country.

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.

[5] 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.

The spill gates sent down 750 cumecs (7.5 lakh litres per second) of water downstream, along with the heavy downpours resulting in widespread flooding along the state's longest river.