Explainer: Why Kerala and Tamil Nadu have fought for decades over the Mullaperiyar dam

The Supreme Court on Thursday directed the Centre and the governments of Kerala and Tamil Nadu to set up three panels to prepare a contingency plan in case of a disaster at the 122-year-old Mullaperiyar dam. The dam situated at the confluence of the Mullayar and Periyar rivers is located entirely in Kerala but operated by the Tamil Nadu government for its irrigation and power generation needs.

The Supreme Court specified that the three panels, working in tandem, would only look into preparing a disaster management plan. It said other concerns pertaining to the dam’s stability and lifespan would continue to be examined by an existing committee set up in 2014.

Thursday’s order was in response to a petition filed by Kerala resident Russel Joy, who had moved the court on behalf of three million people living in the vicinity of the reservoir. The petition claimed that their lives would be in danger if the dam were to burst, as the hilly terrain would make the water “rush like a bullet” and cover the thickly populated area in no time.

This fear of a possible calamity that would put millions of lives at risk has underscored the tussle between the two states over the Mullaperiyar dam for close to five decades now. Over the years, the dam has been the subject of numerous legal battles and there are multiple threads to the Mullaperiyar story – of safety, historicity and anxieties over the sharing of resources.

Long history

The dam was built in the late 1800s in the princely state of Travancore (present-day Kerala) and given to British-ruled Madras Presidency on a 999-year lease in 1886. The agreement granted full rights to the secretary of state of Tamil Nadu, a British official, to construct irrigation projects on the land. The dam was built to divert eastwards a part of the west-flowing Periyar river, to feed the arid areas of Tamil Nadu.

The agreement was renewed by the two state governments in independent India in the 1970s. Tamil Nadu was given rights to the land and the water from the dam as well as the authority to develop hydro-power projects at the site, and Kerala would receive rent in return.

However, safety concerns surfaced in 1979 after reports in the Kerala press claimed a minor earthquake had caused cracks in the dam. The Central Water Commission was asked to examine the structure and suggest ways to strengthen it. As an emergency measure, the commission recommended that the level of water stored in the reservoir be lowered to 136 feet from about 142 feet. It held that the water level could be raised to the dam’s full capacity of 152 feet after the structure was strengthened.

Claims and counter claims

From this point on, two divergent perspectives have emerged.

Tamil Nadu claims that though it has undertaken periodic repairs on the dam, the Kerala government has not allowed it to raise the water level. It says it has suffered huge losses from not being able to use the dam to its full capacity.

Kerala, on the other hand, contends it is not safe to raise the water level as Idukki district, where the dam is located, is earthquake-prone and has experienced multiple low-intensity quakes. Scientists, too, have said the dam cannot withstand an earthquake measuring over six on the Richter scale and that if such a calamity were to happen, the lives of more than three million people would be imperilled.

The divergent views resulted in the two states moving their high courts and multiple petitions being filed. In 2000, the matter reached the Supreme Court, where it has been hotly contested for years.

In 2006, the Supreme Court allowed the Tamil Nadu government to raise the water level to 142 feet, contending that the apprehensions raised by Kerala were baseless. The Kerala government countered this with an amendment to the 2003 Kerala Irrigation and Water Conservation Act. The amendment classified the Mullaperiyar dam as endangered and restricted the level of water in it to 136 feet. Tamil Nadu responded by moving the Supreme Court, calling for the amendment to be struck down as unconstitutional.

On its part, the top court tried to get the two sides to find common ground, but both stood firm. The Kerala government commissioned a study by the Indian Institute of Technology, Roorkee, at the site of the dam. The study reiterated that the dam would not be able to withstand a major earthquake. Armed with these findings, the Kerala government in 2009 proposed that a new dam be built at the site. But Tamil Nadu was not convinced.

In another attempt to broker an agreement, the Supreme Court in 2010 set up a five-member empowered committee to look into the various concerns raised by the states. As the two sides were awaiting the committee’s report, a series of low-intensity earthquakes struck Idukki in 2011. Media reports in Kerala said the quakes had caused cracks to appear on the dam’s surface. This led to protests across the state demanding that the dam be decommissioned. The protests turned violent in many parts and worsened ties between the two states.

However, a year later, the empowered committee declared that the dam was “structurally and hydrologically safe” and that the Tamil Nadu government could raise the water level to 142 feet after carrying out some repairs.

The Kerala government received yet another setback in 2014 when the Supreme Court held that the 2006 amendment to the Kerala Irrigation and Water Conservation Act restricting the water level in the dam to 136 feet was unconstitutional. It said Kerala could not obstruct Tamil Nadu from raising the water level to 142 feet. To allay Kerala’s concerns, it directed that a three-member committee be set up to oversee the process of raising the water level, inspect the dam routinely and look into the safety concerns.

Three years after this verdict, the court’s latest order on Thursday shows that the Mullaperiyar dam continues to be a bone of contention between Kerala and Tamil Nadu, with mutliple interpretations on everything from the veracity of the 1886 agreement governing its use to the project’s structural safety.