The Mullaperiyar Dam is on the River Periyar and its tributary, the Mullayar in the state of Kerala, hence the amalgamation Mulla-Periyar. It is located 881 m (2,890 ft) above mean sea level, on the Cardamom Hills of the Western Ghats in Thekkady, Idukki district of Kerala, India.
Dispute between Kerala and Tamil Nadu
Kerala has pointed out the unfairness of the 1886 lease agreement and has challenged its validity. However, the danger posed by the 126-year-old dam to the safety of the people of Kerala in the event of a dam collapse has been the focus of disputes from 2009 onwards.
Kerala’s proposal for decommissioning the dam and constructing a new one has been challenged by Tamil Nadu. Tamil Nadu has blamed Kerala for delaying the finalization of the rule curve for the dam.
Supreme Court in 2006 by its decision by a three-member division bench, allowing for the storage level to be raised to 142 feet (43 m) pending completion of the proposed strengthening measures, provision of other additional vents, and implementation of other suggestions.
The safety of the dam again rose to public attention in 2021 after the flood situation in Kerala since 2018 and the destruction of the Rishiganga hydroelectric project & Tapovan dam in Uttarakhand following a glacier burst that killed nearly 200 people.
A UN report on threats possessed by ageing dams across the world stated that the Mullaperiyar dam situated in a seismically active area has major structural flaws and 5 million people are at risk if the 100+ years old dam were to fail. Two petitions were filed in the Supreme Court alleging that the supervisory committee formed as per Supreme Court order in 2014 was not functioning properly for the past 6 years, responding to which the Supreme Court ordered Chief Secretary of Tamil Nadu to come out with the rule curve immediately or face action.