Tamil Nadu moves Supreme Court over Kerala 'obstruction' in Mullaperiyar dam work
The Tamil Nadu government has approached the Supreme Court, alleging that Kerala's “obstructionist attitude” has stalled implementation of a 12-year-old apex court judgment that allowed the state to raise the water level in the Mullaperiyar dam to 142 feet. The complaint was made in a report filed before the court, which also sought permission for essential safety and strengthening works that have been pending for years.
In May 2014, a Constitution Bench of the Supreme Court ruled in favour of Tamil Nadu in the long-standing dispute over the 131-year-old dam. The court declared the structure safe and allowed Tamil Nadu to raise the reservoir water level from 136 feet to 142 feet, subject to completion of strengthening measures. A subsequent 2006 judgment had permitted a gradual increase up to 152 feet after the required works were finished.
The dam, located in the Idukki district of Kerala, was built under the Periyar Lake Lease Agreement of October 29, 1886. Construction took around eight years and was completed in 1895. Although the dam stands in Kerala, it is owned and operated by Tamil Nadu. The main dam is 1,200 feet long with a top level of 155 feet.
In its report, Tamil Nadu said Kerala has not cooperated in the timely completion of measures to strengthen the baby dam, the earth dam, and the grouting of the main dam—all considered critical for structural safety. The state has urged the court to allow it to fell trees near the dam site to facilitate these long-pending safety works, and has also sought permission to complete grouting operations.
Tamil Nadu accused Kerala of “double standards” on the issue. It noted that a senior counsel for Kerala had informed the court on July 31, 2025, that the state government had already granted necessary permissions for the work. However, the report states that no proposal was received in the Ministry for consideration of the Standing Committee of the National Board for Wild Life, contrary to what was recorded in court. Tamil Nadu also alleged that Kerala was delaying permission for transporting grouting materials and machinery.
Another instance cited by Tamil Nadu involves a request from Kerala in November 2025 to deposit an initial cost estimate of ₹87,64,000 for repairing the approach road from Vallakkadavu to the dam site. Tamil Nadu said it granted administrative sanction for the amount by February this year, but Kerala has yet to begin the work.
The report also drew attention to the absence of an Emergency Action Plan (EAP) for the dam. The National Dam Safety Authority shared the Terms of Reference and hazard classification for the Mullaperiyar dam in May last year, but no action has been taken to prepare the plan. Additionally, Kerala has not shared real-time rainfall and flood data from the dam's catchment area, which is necessary for inflow forecasting and safety management.
The Mullaperiyar dam has been a subject of tension between the two states for decades. Tamil Nadu maintains that the dam is safe and that strengthening works are needed to protect the downstream population and ensure water supply. Kerala has expressed concerns about the structural integrity of the aged masonry dam and has called for a new dam, leading to prolonged legal and political disputes.
The Supreme Court is expected to consider the fresh report as it continues to monitor the safety measures and the implementation of its earlier orders. The outcome of this hearing could have significant implications for the management of the dam and the relations between the two southern states.
