<Tr> <Th> Normal elevation </Th> <Td> 732.62 m (2,404 ft) </Td> </Tr> <P> The Cheruthoni Dam, located in Idukki District, Kerala, India, is a 138m tall concrete gravity dam . This dam was constructed as part of the Idukki Hydroelectric Project along with two other dams at Idukki and Kulamavu . The project was completed with Canadian aid . The Government of Canada aided the Project with long term loans and grants . S.N.C. Inc., Canada, a firm of Consulting Engineers were advising and assisting Project Engineers under the Canadian Aid . </P> <P> The water impounded by these three dams of Idukki, Cheruthoni & Kulamavu has formed a single reservoir spread over 60 sq.km on a height of 2300 ft above Mean Sea Level . The Idukki Dam is a double curvature arch dam constructed across Periyar River in a narrow gorge between two granite hills and is the tallest double curvature arch dam in Asia. Cheruthoni Dam is located 1 km west of Idukki dam . The spill way of the Idukki Reservoir is in the Cheruthoni dam . Kulamavu Dam was constructed to prevent the water escape through a rivulet called Kilivally, 30 km west to Idukki Arch Dam . It is a 100 metres tall Masonry gravity dam . Construction of this Cheruthoni Dam, Idukki Arch Dam and Kulamavu Dam created an artificial lake of 60 km and the water stored, is used for production of electricity at the Moolamattom Power house . The power house at Moolamattom is the biggest underground power station in India and the pressure shaft is the largest in the country . Cheruthoni is the largest and highest gravity dam in Kerala . Storage of water in Idukki Reservoir started in February, 1973 . Moolamattom Power Station was Commissioned in February 1976 by Prime Minister Indira Gandhi . </P> <P> 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 . </P>

What is the difference between idukki dam and cheruthoni dam
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