The Mullaperiyar Dam issue is a longstanding and contentious dispute between the Indian states of Tamil Nadu and Kerala over the operation, safety, and management of the Mullaperiyar Dam. Here is a detailed overview:

Key Facts About Mullaperiyar Dam

1. Location: The dam is situated in the Idukki district of Kerala but is operated and maintained by Tamil Nadu under a 999-year lease agreement made during British rule in 1886.
2. Purpose: It was built to divert water from the Periyar River in Kerala to the Vaigai River in Tamil Nadu for irrigation and drinking water purposes.
3. Construction: The dam, constructed in 1895, is a masonry gravity dam built using lime surkhi mortar.

1. Safety Concerns: Kerala has raised serious concerns about the dam's structural stability, especially considering its age (over 125 years) and its location in a seismically active zone. Kerala fears a catastrophic failure could endanger the lives of millions in the downstream areas.
2. Water Level Dispute:
   • Tamil Nadu seeks to maintain the water level at 142 feet, as permitted by the Supreme Court of India in 2014, to ensure adequate water for irrigation and drinking purposes.
   • Kerala insists on limiting the water level to 136 feet, citing safety concerns.
3. Structural Integrity: Kerala has proposed constructing a new dam downstream to replace the existing one, but Tamil Nadu opposes this, fearing it would affect its rights over the dam and water.
4. Interstate Relations: The issue is not just technical but also a sensitive political matter, impacting relations between the two states.

Legal and Judicial Developments

1. Supreme Court Judgments: The Supreme Court has delivered several judgments in the dispute. Notably, in 2006 and 2014, it allowed Tamil Nadu to increase the water level to 142 feet after strengthening the dam.
2. Supervisory Committee: A committee was set up by the Supreme Court to monitor the water level and ensure dam safety.
3. Ongoing Cases: The matter is still under legal scrutiny, with both states making periodic submissions to the Supreme Court.

Environmental and Social Concerns

• Environmental Impact: Any failure of the dam could lead to severe ecological damage in the Periyar basin.
• Humanitarian Risk: Millions of people in Kerala's downstream areas face a potential disaster if the dam fails.

As of now, Tamil Nadu continues to operate the dam under the lease agreement, while Kerala pushes for the construction of a new dam to replace the old structure. Periodic inspections and legal battles continue to shape the trajectory of this dispute.