Mullaperiyar Dam is constructed over the headwaters of the Periyar River in Kerala, India. The Periyar National Park, Thekkady is located around the Periyar reservoir formed by the backwaters of this dam. Although the dam is situated at Thekkadi in Kerala, it is owned and operated by the Government of Tamil Nadu. Due to heavy rains, the water level in the dam is rising. Storing more water in the already week dam cause problems to Kerala.

Tamil Nadu is entitled to draw the entire water flowing into this reservoir for its irrigation needs, according to the Mullaperiyar pact between the two States.

Tamil Nadu is also generating power using this water at a power station on its side of the inter-State border. Kerala gets only the water overflowing from the reservoir. This happens very rarely since the Tamil Nadu engineers diligently plan the storage and diversion of water from the reservoir.

Originally, the maximum permissible level in the reservoir was 152 feet. This was brought down to 136 feet in 1979 due to fears about the safety of the lime and mortar dam, which was built more than a hundred years ago. Despite the reduction in the level, Tamil Nadu has always managed to take optimum advantage of the inflow to the reservoir.


Only on a couple of occasions during the last 26 years had the reservoir overflowed. The last time this occurred was in December 1998, when Kerala received water worth a few million units of electricity from there. The overflow from Mullaperiyar goes straight to the reservoir of Idukki hydel project, the biggest in the State.

History of Dam

The structure was conceived by the British during the colonial rule to divert the waters of the Periyar River eastwards through the construction of a masonry dam, and taking the water from the reservoir through a tunnel cut across the watershed and Western Ghats to the arid rain shadow regions of Theni, Madurai District, Sivaganga District and Ramanathapuram Districts of Tamil Nadu. The Princely State of Travancore was forced to sign a treaty in 1886 in this regard to lease the dam site for 999 years to the then Madras government. The lease provided the British the rights over "all the waters" of the Mullaperiyar and its catchment, for an annual rent of Rs. 40,000.

The dam was built by the British Army Engineering corps. The first dam was washed away by floods, and a second masonry dam was constructed in 1895.