The Tamil Nadu government has approached the Supreme Court, accusing Kerala of adopting an "obstructionist attitude" that has delayed implementation of a 2014 apex court order on the Mullaperiyar dam and seeking permission to undertake long‑pending strengthening and safety works at the reservoir in Idukki district.
Background and legal benchmarks
In a report filed before the top court, Tamil Nadu noted that a Constitution Bench of the Supreme Court, on May 7, 2014, held the century‑old dam structurally safe and permitted raising the full reservoir level from 136 feet to 142 feet. The State reminded the court that an earlier 2006 judgment had envisaged a further permissible rise to 152 feet after completion of prescribed strengthening measures.
The report, prepared by advocate B. Karunakaran and settled by senior advocate G. Umapathy, says Kerala has not cooperated with timely completion of critical works including strengthening of the baby dam, repairs to the earth dam and grouting of the main masonry structure—steps Tamil Nadu regards as essential for structural safety.
Works sought and obstacles cited
Tamil Nadu has urged the court to allow felling of trees near the Mullaperiyar site to facilitate the proposed works and to permit continuation and completion of grouting on the main dam. The State described the delays as contrary to earlier assurances recorded in the top court.
"No proposal was received in the Ministry for consideration of the Standing Committee of the National Board for Wild Life, which is contrary to the recorded statement of senior counsel for Kerala on July 31," the filing said, also accusing Kerala of "double standards."
Located in Idukki district, the masonry dam was constructed under the Periyar Lake Lease Agreement dated 29 October 1886 and completed in 1895. Tamil Nadu operates and owns the reservoir, while the structure physically sits within Kerala territory. The main dam has a reported length of 1,200 feet and the top of the dam reaches 155 feet.
Technical elements on record
The legal filings emphasise three categories of work described as critical:
- Grouting of the main masonry dam to address seepage and voids;
- Strengthening of the baby dam and associated earthworks that buttress the reservoir system;
- Tree‑felling near the work site to permit machinery access and construction activity.
| Date / Year | Detail |
|---|---|
| 1886 | Periyar Lake Lease Agreement signed |
| 1895 | Dam construction completed |
| 2006 | Judgment envisaging possible rise to 152 ft after strengthening |
| 2014 (May 7) | Supreme Court allowed raising level to 142 ft, declared dam structurally safe |
Inter‑state sensitivity and administrative process
The Mullaperiyar dispute sits at the confluence of engineering, ecology and inter‑state relations. Tamil Nadu has argued that federal and expert clearances, including consideration by the Standing Committee of the National Board for Wildlife where relevant, should not be used to stall court‑mandated safety measures. Kerala’s objections historically have centred on safety risks to populations downstream and ecological concerns arising from changes to reservoir operation.
The current filing states that Kerala’s representations before the court in July 2025 indicated that necessary permissions had already been accorded by the State government—an assertion Tamil Nadu says was not reflected in formal proposals to central bodies.
What happens next
The matter is before the Supreme Court, which will have to weigh Tamil Nadu’s prayer for permission to carry out the specified works against any environmental or administrative conditions that may be imposed. Any clearance to raise the reservoir level or to permit intrusive engineering works will involve technical scrutiny and coordination between the two States and relevant central authorities.
Given the dam’s age and the potential downstream consequences, the case will be monitored closely by local communities, district administrations and water management agencies. The court’s next hearings will determine whether the long‑deferred strengthening measures can proceed without further delay.
— Reported from Idukki
