The Mullaperiyar Dam is a dam on the Periyar River in the Indian state of Kerala  It is located 881 m above sea level, on the cardamom hills of the Western Ghats in Thekkady, Idukki district of Kerala, in southern India. It was built between 1887 and 1895 by the British government to divert water eastward to the territory of the madras presidency (now Tamil Nadu). It has a height of 53.6 meters of foundations and a length of 365.7 meters.  Thekkady Periyar National Park is located around the lake`s holding lake. The dam is located in Kerala, on the Periyar River, but it is controlled and operated by the neighbouring state of Tamil Nadu.  Although the Periyar River has a 5398 km2 watershed of 114 km2 in Tamil Nadu, the Mullaperiyar Dam basin is itself entirely located in Kerala.   The control and security of the dam, as well as the validity and fairness of the lease agreement, were points of disagreement between the states of Kerala and Tamil Nadu.  The Supreme Court`s decision was issued on 27 February 2006, which allowed Tamil Nadu to raise the dam level to 46 m after it was reinforced. In response, the Kerala government declared the Mullaperiyar dam “threatened” in 2006 by the Kerala government.  The dispute between the states of Kerala and Tamil Nadu must be careful about the control and safety of the dam, as well as the validity and fairness of the lease.
The dispute began in 1998, when Tamil Nadu wanted to raise the water level and kerala opposed it. The case arrived before the Supreme Court on 27 February 2006, after being tried before the Madras and the Kerala High Court. In February 2006, the Supreme Court allowed Tamil Nadu to raise the water level of the dam to 46 m. In response to the adoption by the Kerala government of the Irrigation and Water Protection Act (Amendment) in 2006, in order to ensure the safety of all dams at risk in the state, according to which the second timetable of the Mullaperiyar dam, built in 1895 as threatened, sets its maximum water level at 136ft.