• Kerala has secured a major victory in the Mullaperiyar dam case, with the Central Water Commission deciding to conduct a safety audit within 12 months. 

• The decision was taken at a meeting of the CWC held in New Delhi on September 2.

Demand for new Mullaperiyar dam

• The last safety audit of the century-old structure was done in 2011. Kerala has been demanding a fresh audit at the earliest, considering more than a decade has passed. 

• The state witnessed a couple of heavy floods and a series of fatal landslides in the hilly districts that triggered panic among the public.

• However, Tamil Nadu had contended that the next audit wasn’t necessary under the Dam Safety Act of 2021, at least until 2026.

• Kerala has repeatedly said the masonry dam opened in 1895 over the Periyar in Idukki district was unsafe. 

• It has been demanding the decommissioning of the existing dam and constructing a new one in the downstream region of Mullaperiyar Dam. Tamil Nadu relies on the dam for irrigation purposes.

History of Mullaperiyar dam case

• Mullaperiyar dam was constructed pursuant to the Periyar Lake Lease Agreement of October 29, 1886 across the Periyar river. 

• The construction continued for about eight years and was completed in 1895.

• A lease indenture for 999 years was made on October 29, 1886 between Maharaja of Travancore and secretary of state for India for Periyar irrigation works.

• By another agreement in 1970, Tamil Nadu was permitted to generate power also. 

• Its full reservoir level is 152 ft and it provides water through a tunnel to Vaigai basin in Tamil Nadu for irrigation benefits.

• The dam is located in a seismically active area.

• In 1979, reports appeared in the media about damage to the dam. In November 1979, some emergency medium term measures and long-term measures for strengthening of Mullaperiyar dam were decided. 

• Later, the matter became sub-judice with several petitions.

• Leaks and leaching are also concerning, as the methods and materials used during construction are considered outdated compared to current building standards.

• In 2000, on the directions of the Supreme Court, an expert committee with representatives from both states was constituted to study the safety of the dam. The Committee in its report opined that with the strengthening measures implemented, the water level can be raised from 136 ft To 142 ft without endangering safety of the dam.

• In 2006, the Supreme Court permitted the government of Tamil Nadu to raise the water level of Mullaperiyar dam from 136 ft To 142 ft and to carry out the remaining strengthening measures. 

• After that, the government of Kerala passed the Kerala Irrigation and Water Conservation (Amendment) Act, 2006 which prohibited the raising of water level beyond 136 ft in the Mullaperiyar Dam and placed it in the Schedule of ‘Endangered Dams’.

• A Constitution Bench, consisting of five judges of the Supreme Court, heard the case in 2013.

• In its May 7, 2014 verdict, the Supreme Court held that the Mullaperiyar Dam is safe and allowed the Tamil Nadu government to raise the water level to 142 feet.

Dam Safety Act

• The Dam Safety Act addresses longstanding concerns about the safety of major dams across India. 

• Effective from December 2021, it aims to prevent dam failure disasters through measures such as surveillance, inspection, operation, and maintenance. 

• The Act establishes institutional mechanisms to ensure the safe functioning of dams.

Key provisions of the Act:

• The Act applies to dams over 15 meters in height and those between 10 and 15 meters with specific stipulations.

• Dam Safety Act, 2021 provides for four tiers of institutional mechanism: 

Establishment of National Committee on Dam Safety (NCDS) and National Dam Safety Authority (NDSA) at Centre level and establishment of State Committee on Dam Safety and the State Dam Safety Organisation at state level.

• Dam owners are held accountable for the construction, operation, maintenance, and supervision of dams.

Dam Safety Act and Mullaperiyar Dam:

• According to the Act, the NDSA acts as the State Dam Safety Organisation for dams located in one state but utilised by another, such as the Mullaperiyar dam.

• Experts suggest that the central government may propose in court that the NDSA can take over the supervisory committee’s functions concerning the Mullaperiyar dam.

(The author is a trainer for Civil Services aspirants.)