Water release at Mullaperiyar dam creates tension between Kerala and Tamil Nadu

Kerala CM Pinarayi wrote to his TN counterpart MK Stalin on December 2 seeking intervention from the latter.
Water being released from the shutters of Kerala's Mullaperiyar dam.
Water being released from the shutters of Kerala's Mullaperiyar dam.
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For decades, the Mullaperiyar dam has been a bone of contention between Kerala and Tamil Nadu. Now, the latest tension between the two states has come after Kerala has alleged that TN is releasing water from the dam with little to no prior intimation to the former. On December 2, Tamil Nadu released water from the spillway shutters of the Mullaperiyar dam in Idukki. Kerala, however, alleges that the 10 shutters were open at odd hours, between 2.30 am and 3.30 am, without any notice to authorities or people living downstream in Kerala’s Idukki district.

The result was that water entered people’s homes, causing panic and creating a flood-like situation in the region. People in Idukki began to fear that they would face deluges, similar to those experienced in 2018 and 2019. In response, Chief Minister Pinarayi Vijayan has written to Tamil Nadu CM MK Stalin seeking intervention to allay the fears of Idukki residents living downstream from the dam. 

As per the Kerala CM’s letter, shutters four to eight of the Mullaperiyar dam were opened at 3 am on December 2. "Sufficient warning was not given before substantial discharge of 6, 413 cusecs, which were subsequently increased to 8,017 cusecs at 4 am by opening all the 10 shutters," it reads.

Tamil Nadu has denied the allegations from the Kerala government. 

Shutters opening: How it’s communicated

The dam, which is over a century old, is built on the Periyar River in the Idukki district of Kerala, but is managed by the neighbouring Tamil Nadu district. In 2014, the Supreme Court allowed the water level to be raised to 142 feet, with a provision for up to 152 feet after requisite strengthening measures were made. This was the fourth time that the water level in the dam touched 142 feet, with previous instances in 2014, 2015 and 2018. 

Tamil Nadu has an office at Kambam in Theni district, which borders Kerala. An Executive Engineer is in charge at the site. The communication for opening the dam shutters is sent from the engineer to his counterpart in Kattappana in Kerala who, in turn, informs the Idukki District Collector. The district administration is in charge of shifting people and issuing an alert. As per the orange book of the Kerala State Disaster Management Authority (KSDMA), an alert should be sent six hours prior to the opening of the dam shutters.

“But after the rule curve (fixed by the Central Water Commission) came into existence Tamil Nady began to inform us about half an hour or one hour before. The water level would be fixed [on normal rainy days] for a week [so that no abrupt move would need to be taken]. This time they released water at 2.30 am and 8017 cusecs of water was released in total without prior notice. We won’t be able to manage if it’s beyond 5,000 cusecs as it causes water to enter houses,” an official of the Kerala Water Resources Department told TNM.

The rule curve refers to the buffer or empty space that must be maintained at different periods in a year. 

“We ask TN not to release water during the night, and to release water in a controlled manner during the day and maintain the water level within the dam (without releasing water) when the rain is moderate,” a source with the Water Resources Department, told TNM.  “Usually, TN would give an alert one hour prior to releasing water. But this time that didn’t happen. The alert was given 15 minutes after two shutters were open. Giving alerts at odd hours won’t do any good for us as we won’t be able to alert people. They cannot shift them to safer regions as they are sleeping,” he added.

On December 1, the water level had reached 142 feet by that night. “The water was released during odd hours so as to maintain the 142 feet by the morning. What we demand is not to open the shutters during odd hours and to open the shutters when the water level is anticipated to reach 142 feet. That should be done by opening one or two shutters by 10 or 20 centimeters so that the water level can be kept below 142,” the source added.

Tamil Nadu however denies this. Executive Engineer of the Mullaperiyar dam Sam J Irvin told TNM that the relevant information was provided and questioned why Kerala officials posted at the dam did not inform the state. “We have given all alerts. Moreover, Kerala officials have been posted at the dam for 40 days and they take down hourly notings of water level. Why post this staff then?”

When TNM asked Kerala whether their officials were posted at the dam, the government confirmed the same. “Our officials sit at the dam when the water touches 138 feet. But they are there only to calibrate data. Alerts have to be given as per procedure,” the source in the Water Resources Department alleged. 

According to dam safety expert James Wilson, the confusion arises due to the 142-foot level. “One is a permitted level as per the SC judgement in 2006, which was reiterated in 2014. This is all about structural safety. Here you can't go beyond that level in Mullaperiyar dam, unless the reservoir rises due to natural backwater effect,” he said. However, the rule curve dictated at 142 feet is all about operational safety, he said. 

“If the rule curve acknowledges 142 feet, here it is equal to permitted Full Reservoir Level (FRL) at the end of the season. But if you blindly follow it, you will be forced to throw all the water downstream in case it rains. So prudence is required when there is cyclonic circulation prevailing and heavy rainfall alerts are around. One should never store upto FRL. But there may be political compulsions that may be causing TN to store up to 142 feet, which is creating problems of late,” he said.  

Water Resources Minister Roshy Augustine held a press meet in Idukki on December 2 criticising Tamil Nadu’s decision regarding the dam. The minister termed the TN move as unfortunate and unexpected, and that Kerala is viewing this with great seriousness. In November, he had blamed TN for not maintaining the rule curve level and said that it would be informed to the supervisory committee and the Supreme Court.

With inputs from Nirupa Sampath  

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