- It is a masonry gravity dam on the Periyar River in Idukki District of Kerala
- The dam situated at the confluence of the Mullayar and Periyar rivers
- The Periyar National Park in Thekkady is located around the dam’s reservoir.
- The dam was built in the late 1800s in the princely state of Travancore (present-day Kerala) and given to British-ruled Madras Presidency on a 999-year lease in 1886.
- The dam is located in Kerala on the river Periyar, but is operated and maintained by Tamil Nadu state.
- The agreement was renewed in 1970.
- Tamil Nadu was given rights to the land and the water from the dam as well as the authority to develop hydro-power projects at the site, and Kerala would receive rent in return.
Purpose of the dam
- The Periyar river which flows westward of kerala Arabian sea was diverted eastwards to flow towards the Bay of Bengal to provide water to the arid rain shadow region of Madurai in Madras Presidency which was in dire need of a greater supply of water than the small Vaigai River could provide
- For Tamil Nadu, the Mullaperiyar dam and the diverted Periyar waters act as a lifeline for Theni, Madurai, Sivaganga and Ramnad districts, providing water for irrigation and drinking, and also for generation of power in Lower Periyar Power Station.
- It states that it does not object to giving water to Tamil Nadu, their main cause of objection being the dam’s safety as it is more than 100 Years old.
- Mullaperiyar dam has leaks and cracks in the structure. Increasing the level would add more pressure to be handled by the already leaking dam
- Idukki district, where the dam is located, is earthquake-prone and has experienced multiple low-intensity quakes. So, the dam is situated in a seismically active zone
- A 2009 report by IIT Roorkee stated that the dam “was likely to face damage if an earthquake of the magnitude of 6.5 on the Richter scale struck its vicinity when the water level is at 136 feet”
- It poses danger to life and property to people living downstream
- Three million people living in the vicinity of the reservoir.
- On the orders of the CWC, the Tamil Nadu government lowered the storage level from 152 feet to 142.2 feet then to 136 feet, conducted safety repairs and strengthened the dam
- It becomes difficult to sustain agriculture if water level is not increased
- One estimate states that “the crop losses to Tamil Nadu, because of the reduction in the height of the dam, between 1980 and 2005 is a whopping ₹ 40,000 crores.
- The dam has been strengthened and there will be no threat to people and the tremors that felt in neighborhood was minor
Other Issues between them
- With Kerala, Tamil Nadu has issues on several river waters, such as Parambikulam-Aliyar, Siruvani of the Bhavani sub-basin, Neyyar, and the proposal for linking the Pamba and Achankovil rivers of Kerala with Vaippar of Tamil Nadu. But, in the case of Karnataka, Cauvery is the only river to be considered.
- 2006: SC allowed Tamilnadu to raise water height to 142 feet after strengthening the dam. (Total height of the dam is 176 feet) while permissible is 152 feet.
- But Kerala passed a law the Kerala Irrigation and Water Conservation (Amendment) Act, 2006, to prevent the neighboring State (TN) from raising the water level beyond 136 feet.
- Tamilnadu challenged Kerala’s dam height law in Supreme Court.
May 2014: Supreme Court order
- Kerala dam Law of 2006 is unconstitutional and void. Because Mullaperiyar is a dispute between two states. In such disputes, one state legislature cannot unilaterally enact law in its own favor.
- Besides, in 2006 SC allowed Tamilnadu to raise water height. By enacting this law, Kerala is interfering with our judicial function.
- Permanent Supervisory Committee
- The Committee shall inspect the dam periodically, more particularly, immediately before the monsoon and after the monsoon and keep close watch on its safety and recommend measures which are necessary.
- The Committee shall be free to take appropriate steps and issue necessary directions to the two States Tamil Nadu and Kerala or any of them if so required for the safety of the Mullaperiyar dam in an emergent situation. Such direction shall be obeyed by all concerned.