While the states of Tamil Nadu and Kerala have opposing stands on the Mullaperiyar dam, civil society actors have provided alternatives to the old dam whose decommissioning is bound to happen sooner or later. They have also pointed out the inappropriateness of building a new dam on Mullaperiyar. Latha Anantha of the River Research Centre, Thrissur, speaks to India Water Portal on the issue. 

Tell us more about this dam which divides the two States of Tamil Nadu and Kerala.

Perhaps history would tell us that the Mullaperiyar dam is the oldest, most debated and prolonged dispute between two States over water sharing and dam safety issues in India! The irony is that while most of the debates and legal interventions are over dam safety issues, the inherent problems with the outdated Mullaperiyar Agreement and the associated environmental issues are yet to be taken up seriously in these changed times.

The Mullaperiyar dam is probably one of the earliest attempts at inter basin diversion of water in India in the name of transferring water from a ‘surplus’ to a ‘deficit’ river basin. Believed to be an engineering marvel of those times, the masonry dam, also the first of its kind in India was built between 1887- 95 by the erstwhile Madras Presidency (now Tamil Nadu) on the land of erstwhile Travancore (presently in Kerala). The dam was built as per the historic Periyar Agreement signed in 1886 by the two parties. As per this, the west flowing waters of Periyar were diverted towards Tamil Nadu. The land on which the dam stands was leased out by what is now Kerala to Tamil Nadu for 999 years at a nominal lease rent and the dam is completely controlled and operated by Tamil Nadu since then. 

What is the legal dispute between the two States related to the dam?

The dispute between Kerala and Tamil Nadu over the age and leakages-related safety has been raging for several years now. Large scale seepage from the dam started in the late 70s. Kerala apprised the Central Water Commission (CWC) of the situation which ordered the lowering of the water level from 142.4 ft to 136 ft along with leak proofing as a precautionary measure in 1979. Tamil Nadu maintained that all measures for strengthening the dam were undertaken by them as per directions, while Kerala argued otherwise. In fact, Tamil Nadu sought raising the water level to 152 ft.

This eventually led to the filing of a number of writ petitions in the Kerala High Court as well as in the Madras High Court sometime in 1998 on the issue for and against the raising of the dam’s water level as well as regarding its safety. Due to the nature of the conflict and the possibility of conflicting judgments from the two Courts, all the cases were later transferred to the Supreme Court. The Ministry of Water Resource’s efforts to amicably resolve the issue were in vain. An Expert Committee led by a CWC member constituted to examine the safety of the dam and advise the Ministry of Water Resources on the raising of the water level in the reservoir gave the green signal to Tamil Nadu for raising the height to 142 ft. Meanwhile the ‘Mullaperiyar Environmental Protection Forum’ also filed a writ petition against raising the dam's height in Supreme Court.

What did Supreme Court state in its judgement of 2006 and 2014?

The Supreme Court after hearing all the parties in 2006 directed Kerala to raise the height of the dam from 136 ft to 142 ft. This, despite a study carried out by a group of eminent institutions in Kerala on the adverse impact of raising the water level on the Periyar Tiger Reserve. The Supreme Court also observed that after the strengthening work was complete to the satisfaction of Central Water Commission, independent experts would examine the safety angle before the water level is permitted to be raised up to 152 ft ( FRL).

Kerala amended its Kerala Irrigation and Water Conservation Act (2006) and set up a Dam Safety Authority (KDSA) soon after this to advise it on evaluating the safety and security of dams. Mullaperiyar topped the list of unsafe dams on account of its age, degeneration and structural impediments. Tamil Nadu moved the Supreme Court challenging this decision of Kerala.

In 2010 the Supreme Court appointed an Empowered Committee to look into the hydrological, structural and seismological safety of the old dam. The Committee gave a clean chit to the 120 year old dam. 

In the final judgment in 2014, the Supreme Court declared the Kerala Irrigation and Water Conservation Act 2006 Amendment as unconstitutional in its application on the Mullaperiyar dam. By an order of permanent injunction, Kerala was restrained from using the Amendment to the Act in preventing Tamil Nadu from raising the water level to 142 ft and carrying out repair works as per the earlier judgment of 2006 and later to 152 ft after completion of maintenance works

A Supervisory Committee was constituted to inspect the dam periodically, to supervise the restoration of the water level to 142 ft. Meanwhile Kerala’s suggestion to construct a new dam at its own expense just downstream of the present one was rejected outright by Tamil Nadu, and the Supreme Court supported them on their stand.

The old structure seems very risky based on a report by the Centre for Earth Science Studies which says that it cannot withstand an earthquake above magnitude 6 on the Richter scale. Please tell us more about the safety aspects related to the dam. 

The 120 year old dam has clearly outlived its viable age and indeed poses a threat to the downstream populace and dams in case of a dam break. The collapse of the dam would trigger the cascading failure or collapse of the immediate downstream Idukki, Cheruthoni and Kulamavu dams of the Idukki hydroelectric project and many others in surrounding areas. The resulting catastrophe would be unimaginable devastation of thickly populated districts downstream. Studies have revealed that the Idukki dam may not be able to hold the waters of the Mullaperiyar.

The study by the Centre for Earth Science Studies states that the unique construction material and the seismological location of the dam make it vulnerable. Assessments by IIT Delhi and IIT Roorkee for the Government of Kerala reveal that the old dam is structurally and hydrologically unsafe to withstand the impact of Probable Maximum Flood and Probable Earthquake. Kerala had raised this aspect in the Supreme Court challenging the estimation of Probable Maximum Flood arrived at by the Central Water Commission.

The Mullaperiyar issue should have become the forerunner to put in place a comprehensive Dam Safety Act given the large number of dams that have crossed the 50 years lifespan which is the viable age of a dam as per international standards.

The Mullaperiyar dam is over 100 years old and its decommissioning is bound to happen sooner or later. In a recent move, the Supreme Court has allowed Kerala to carry out Environmental Impact Assessment for the new Mullaperiyar dam in place of the old one. Has the Supreme Court given a go ahead to decommissioning the old dam?

It is just a matter of time. The Mullaperiyar dam cannot be expected to remain forever. Recently the Kerala Government has approached the Ministry of Environment and Forests and Climate Change (MoEF&CC) with a proposal for a new dam downstream of the present one. The present move is based on the Standing Committee of National Board for Wild Life’s (NBWL SC) go ahead signal to Kerala for conducting an Environment Impact Assessment for the new dam. The proposal came up for consideration of Terms of Reference before the Environmental Appraisal Committee on River Valley projects on June 3rd and 4th 2015. The new dam is proposed in the Periyar Tiger Reserve, an Ecologically Sensitive Zone (ESZ). While the River Valley Committee gave a green signal for an EIA on June 4th, a PIB release from the Government of India on the same day later that night stated that no approval has been given for carrying out a new EIA for the construction of a new dam (for obvious reasons)! While there is no dispute that the present dam needs to be decommissioned partially if not fully, the proposal for a new dam by Kerala cannot be accepted as the only alternative to resolve the issue.

What are the cost effective and environmentally less destructive alternatives to this? 

Over the last 30 odd years, the Mullaperiyar dam issue has grown into a never ending dispute between Kerala and Tamil Nadu with political overtones. Both the states have been unrelenting in their respective stances. The demand for a new dam has been growing stronger from the Kerala side especially from the downstream panchayats given the fear of dam failure. A section of activists and civil society groups in Kerala and across India have been trying to put forward alternate options in place of a new dam which have not been accepted by both Governments so far.

The Forum for Policy Dialogue on Water Conflicts in India with endorsement from eminent experts working in the water sector has put forward the following options:

• Given the intense fear and insecurity amongst the downstream people, and the divided expert opinion on dam safety at higher water levels, it would be best to use the precautionary principle and keep water levels low, to around 120 ft.
• Water can be delivered to Tamil Nadu at 120 ft level and the state should be encouraged to divert as much water as it can and store it inside the state in series of balancing reservoirs or other storages.

Can there be an alternative that is agreeable to both the states?

Long-term action is needed on the following lines:

• Reconfirm Kerala’s commitment to provide the present quantum of water. The Kerala government in any case has publicly confirmed this commitment.
• Come to a common understanding of the role of the Mullaperiyar dam as a diversion weir rather than a storage dam and that the storage capacity needed for Tamil Nadu should be created inside the state with adequate assistance from the centre.
• Immediately undertake studies on
  • the requisite capacity needed inside Tamil Nadu,
  • the redesign of the diversion and conveyance system,
  • on the basis of this, minimizing storage behind the dam as close as possible to the minimum regulatory storage required,
  • measures to strengthen the dam at the new level,
  • hydrological study of flow at the dam site and a schedule for the regulatory storage, and
  • working out arrangements in the transition phase.

Though the dam would continue to be under the control of Tamil Nadu, the Forum suggested that there should be a tripartite board consisting of representatives of the Government of Kerala, Government of Tamil Nadu and the Union Government (on the lines of the Tungabhadra Board) that oversees the preparation of a reservoir operation plan and monitors and modifies it throughout the year.

A strategy of local water harvesting and increase of on-field and irrigation efficiency so as to gradually reduce the requirement from the Mullaperiyar allowing eventual decommissioning was also suggested. In fact, the Forum believes that ultimately one should move to ecosystem-based river basin planning. Such an option while fulfilling Tamil Nadu’s rights over water and land, would also reduce the burden of storing the water for Kerala.

An important aspect which has seldom been discussed in the case of Mullaperiyar is the issue of environmental flows below the dam into Kerala. For 120 years, the river below the Mullaperiyar dam has been deprived of its legitimate share of water except in the monsoon season. In the overemphasis on technical aspects of dam safety and water level, the need for the ‘river to flow’ has been clearly overlooked even by the Court and the Government of Kerala.

This is an abridged version of the interview. Please download the full interview below.