Mullaperiyar Dam
Context: The Supreme Court authorized Tamil Nadu to proceed with essential maintenance on the Mullaperiyar Dam, including tree removal and road repairs, while directing Kerala to facilitate these activities and setting timelines for unresolved issues.
Important Pointers:
Location: On the Periyar River at Thekkady, Idukki district, Kerala; elevation ~881 m in the Western Ghats
Type: Masonry gravity dam; built at the confluence of Mullayar and Periyar rivers
Construction Period: 1887–1895; constructed by British Corps of Royal Engineers under Col. John Pennycuick
Materials Used: Built using limestone and Surkhi (burnt brick powder + sugar + calcium oxide)
Dimensions: Height – 53.6 m, Length – 365.7 m, Storage capacity – 443 million cubic meters
Reservoir: Forms an artificial lake spanning 8.5 sq. km
Eco-Zone: Lies within the Periyar National Park, a critical biodiversity hotspot
Purpose: Transfers water to the Vaigai River basin in Tamil Nadu for irrigation and hydropower
Operational Control: Though located in Kerala, operated by Tamil Nadu under a 999-year lease (1886) signed during British rule
Inter-State Dispute:
Kerala: Demands dam decommissioning or reconstruction due to safety concerns
Tamil Nadu: Opposes decommissioning; insists the dam is structurally safe
Recent SC Intervention (May 2025):
Approved tree-cutting and material transport for repairs
Directed eco-friendly road repairs in Kerala, monitored by a TN engineer
Instructed consultation with the Supervisory Committee for the grouting of the dam structure
Urged compliance with the Inland Vessels Act and the Wildlife Act
Environmental Sensitivity: Construction and operations involve forest clearance, wildlife regulation, and inter-ministerial approvals