• The shutters of the Mullaperiyar dam in Kerala, operated by Tamil Nadu, were raised on October 29 morning as the water level in the reservoir has crossed 138 feet.

• People living downstream of Mullaperiyar dam were evacuated as a measure of caution ahead of raising of the shutters. According to officials, a total of 1,079 people from 350 families have been evacuated.

• Kerala CM Pinarayi Vijayan had earlier written to Tamil Nadu CM M.K. Stalin, requesting him to ensure that maximum quantity of water is drawn from the dam as the reservoir level may reach 142 feet once the torrential rains intensified in Kerala.

• Mullaperiyar dam, built in 1895 on Periyar river in Idukki district of Kerala, is operated by the Tamil Nadu government for its irrigation and power generation needs. Kerala is insisting on building a new dam, citing safety concerns, but Tamil Nadu is against it, saying the present structure was strong.

History of Mullaperiyar dam case

• Mullaperiyar Dam was constructed pursuant to the Periyar Lake Lease Agreement of October 29, 1886 across the Periyar river. The construction continued for about eight years and was completed in 1895.

• A lease indenture for 999 years was made on October 29, 1886 between Maharaja of Travancore and secretary of state for India for Periyar irrigation works.

• By another agreement in 1970, Tamil Nadu was permitted to generate power also. 

• Its full reservoir level is 152 ft and it provides water through a tunnel to Vaigai basin in Tamil Nadu for irrigation benefits.

• The dam is located in a seismically active area.

• In 1979, reports appeared in the media about damage to the dam. In November 1979, some emergency medium term measures and long-term measures for strengthening of Mullaperiyar Dam were decided. 

• Later, the matter became sub-judice with several petitions.

• Leaks and leaching are also concerning, as the methods and materials used during construction are considered outdated compared to current building standards.

• A row between Kerala and Tamil Nadu States started to grow regarding the best way to manage this ageing infrastructure.

• In 2000, on the directions of the Supreme Court, an expert committee with representatives from both states was constituted to study the safety of the dam. The Committee in its report opined that with the strengthening measures implemented, the water level can be raised from 136 ft To 142 ft without endangering safety of the dam.

• In 2006, the Supreme Court permitted the government of Tamil Nadu to raise the water level of Mullaperiyar dam from 136 ft To 142 ft and to carry out the remaining strengthening measures. 

• After that, the government of Kerala passed the Kerala Irrigation and Water Conservation (Amendment) Act, 2006 which prohibited the raising of water level beyond 136 ft in the Mullaperiyar Dam and placed it in the Schedule of ‘Endangered Dams’.

• A Constitution Bench, consisting of 5 judges of the Supreme Court, heard the case in 2013.

• In its May 7, 2014 verdict, the Supreme Court had held that the Mullaperiyar Dam is safe and allowed the Tamil Nadu government to raise the water level to 142 feet.

• Earlier this week, the Supreme Court, while hearing a plea said Tamil Nadu and Kerala would abide by the water level notified by the expert committee as per which it would be maintained at 139.5 feet till November 10.

What Kerala said in SC?

Kerala said there would be an exponential increase in the water pressure and uplift pressure acting on the dam when the water level is raised from 136 feet to 142 feet. “The consequences of any failure of this dam could be extremely catastrophic and beyond human imagination. The apprehensions of the government of Kerala regarding the life and safety of more than 30 lakh people of five districts residing downstream of the dam has to be given due importance and consideration. Mullaperiyar is exceptionally vulnerable because it has a large catchment area and limited storage capacity. Hence, the logical next step is the construction of a new dam to ensure water to Tamil Nadu and security to people living downstream and to decommission the existing dam,” Kerala said.

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