The Idukki hydroelectric project is the biggest of its kind in the State with an installed capacity of 780 MW. It is one of the highest ten arch dams in the world and the third highest in India after the Tehri Dam (Uttarakhand) and Bhakra Nangal Dam (Himachal Pradesh).
The Rs. 107.5 crore project, built and managed by the Kerala State Electricity Board (KSEB), was commissioned by the then Prime minister of India, Indira Gandhi in 1976. It took 220 lakh man days to complete the project.History
The idea of a hydroelectric project over the Periyar River occurred to W H John, the then superintendent of Malankara Estate. John, in an article published in Malayala Manorama daily in 1935, detailed the prospects of such a project.
Kuravan and Kurathi hills, the core area of the project, were introduced to John by Chemban Kolumban, a member of the local Oorali tribe. Kolumban with his wide knowledge of the forest later became an accomplice of the engineers who came for site inspection. As a token of appreciation for Kolumban’s services, the KSEB later allowed a monthly pension of Rs. 40 to Kolumban. There also stands a memorial to Kolumban on the dam site.
In 1937, two Italian engineers submitted a project proposal for a 50,000 KW hydroelectric project on Periyar River to the Government of Travancore. It was followed by a site visit by a team led by Electricity Chief Engineer of Travancore Government Joseph John in 1947.
In 1956, the Government of India began the site investigation of the project, which was completed in 1961. The project work was started in 1963 and the first phase was inaugurated by the then Prime Minister of India, Indira Gandhi in 1976.
The Idukki reservoir with a capacity of 2 billion tons is formed by two rivers Periyar and Cheruthoni. Water is held in the reservoir with the help of three dams – Idukki, Cheruthoni and Kulamavu. While the Idukki dam is meant for storing the water, Cheruthoni and Kulamavu, which are built at a lower portion of the reservoir, channel the water to the powerhouse.
Power is generated at an underground station situated at Moolamattam. The powerhouse is built in a space carved out of huge granite.
The Idukki project helped a steep rise in power generation in the State. While in 1975, if the total generation in the state was 560 MW, the Idukki project alone could generate 780 MW.