Mullaperiyar Dam

Mullaperiyar Dam is in Idukki district, Kerala, on the Periyar river system. The dam was constructed between 1887 and 1895. Its waters are conveyed eastward through a tunnel to the Vaigai basin in Tamil Nadu, supporting irrigation there. The dam therefore lies in one state while serving water-management purposes in another.

An indenture concluded in 1886 between the ruler of Travancore and the British Secretary of State for India granted a 999-year lease for Periyar irrigation works. The arrangement, and later agreements, became central to Tamil Nadu’s operating and water-use interests and Kerala’s concerns as the state where the dam is located. The two states have disagreed over reservoir levels, dam safety, and the appropriate long-term arrangement.

Safety concerns became prominent in the late twentieth century. The Central Water Commission and inter-state expert processes considered strengthening measures and possible reservoir levels. In its 7 May 2014 judgment in State of Tamil Nadu v. State of Kerala, the Supreme Court of India invalidated a Kerala law that had restricted the reservoir level and directed restoration of the 142-foot level alongside a three-member supervisory committee. Subsequent court proceedings have addressed monitoring, disaster preparedness, rule curves, gate operations, and instrumentation. These institutional decisions document the legal framework; they should not be read as eliminating the need for continued technical monitoring.

The dispute brings together water allocation, infrastructure safety, federal relations, and the risks and benefits experienced in different places. Tamil Nadu depends on diverted water, while Kerala is the downstream location of the structure. Its history illustrates how colonial-era water arrangements can shape modern inter-state governance and why technical review, transparent oversight, and cooperation remain important.