It could be said that every citizen of India, can justifiably take pride in possessing a rare structure in Mullaperiyar Dam, the very first created in the country, perhaps in the world, for trans-basin diversion of water for beneficial use, towards the end of the 19th century, still continuing to serve with its benefits undiminished, through continuous surveillance, maintenance and management by the Tamil Nadu government.

The credit for the concept, design and construction of the Mullaperiyar Dam should go mainly to two British Engineers Major Ryves, the District Engineer of Madurai District, who gave a practical form in 1862 for diversion of Periyar waters to benefit the drought-prone areas of the then Madurai and Ramanathapuram districts and Colonel J. Pennycuick, who not only made a report with detailed estimates for the Mullaperiyar Dam in 1882 but also ventured against all odds in the most inhospitable dense forest, struggling with single-minded devotion for a good cause and completed the structure in 1895.

Just to the west of the Vaigai river basin in Tamil Nadu, on the other side of the Western Ghat ridges, lies the Periyar basin in the Kerala State. The river Periyar, as the name implies, is the one which drains the largest catchment among the west-flowing rivers of the Kerala state.

The river Periyar rises in the Sivagiri peak of the Western Ghats in the Quilon district, 80 km south of Devikulam, at an elevation of about 2,400 m and traverses through the stiff cliffs and dense forests for about 186 km, where the tributary Mullaiyar joins on the right at about an elevation of 850 m. The river then turns west, cuts through the hills in a deep narrow gorge at about 11 km below Mullaiyar junction. It is this narrow gorge in sound hard rock that gave an excellent formation that was chosen by Col. Pennycuick to construct the Mullaperiyar gravity masonry dam. The river Periyar runs through 232 km traversing the taluks of Peermedu and Devikulam and parts of Ernakulam district before draining into the well-known Vembanad lake.

The Madras government entered into correspondences with the erstwhile Travancore government in possession of the territory where the dam was to be built from 1862. The Travancore government, which originally showed interest in launching the Mullaperiyar dam project as a joint project, later pulled out of the joint project suggestions and, by a letter dated October 24, 1873 to the British Resident, offered to accept a sum of Rs. 75,000/- per year from 1882 as lease rent for the site of the reservoir, which was later surveyed to extend over 8,000 acres, and agreed to demise the entire water to be stored therein in favour of the government of Madras. The Lease Deed of 1886, to take retrospective effect from January 1, 1886 between the governments of Travancore and Madras, was finally signed on October 29, 1886 for lease of land for the project works for diversion of the waters to then Madras Presidency.

The argument put forth by the present government of Kerala that the British Government got the inter-state agreement signed exercising their supremacy falls flat with the recorded evidence.

Among the materials of construction, Stone, the principal constituent of the dam, was locally available to be quarried as was the sand in the river. But lime and surki for the mortar, designed as three parts of sand, two of lime and one of surki, had to be transported through dense forests besides several construction equipment, and other materials from the temporary camp at Thekkadi, 13 km off, on the other side of the Ghat.

Five different methods of conveyance were considered, all expensive and difficult to organise including a ropeway across the valley and that which was convenient at the time was adopted.

It should be specifically mentioned that throughout this decade of construction, great effort was taken to ensure the quality of the materials used and the building of the structures through tests, checks and supervision.

As cement had not made its advent in India when the project had been designed and executed, lime surki mortar was used with the lime having been burnt to specification in kiln at site and well ground by a battery of bullock-drawn circular mills and surki being ground to the fineness required by crushers. We are now able to see the result in the dam structure retaining water up to 152 ft. above the river bed for more than a century, with minimum seepage well below the limits prescribed, in spite of the fact that no drilling and grouting was done for consolidation and no drainage gallery was formed in the body of the dam, since both these were unknown practices at that period of time.

On May 29, 1970, the government of Madras signed two supplemental agreements with the government of Kerala, as successors in interest to the original Lease Deed of 1886. By one supplemental agreement, the annual lease rent was enhanced and the fishing rights in the Periyar lake was relinquished in favour of the government of Kerala. By another agreement which came into effect from November 13, 1954, the government of Madras would generate hydro power and pay to the government of Kerala for the electrical energy generated at Rs.12/- KW (kilo watt) year up to 350 million units and at Rs.18/- KW year beyond 350 million units. This will prove that the Mullaperiyar project has been beneficial to both Tamil Nadu and Kerala.

The safety of the dam is now being questioned, just because it is 116 years in age and a fear psychosis has been raised, which gives the impression it may burst any time. No gravity masonry dam will ever burst and no gravity dam has so far burst in any part of the world. The dam is as good as a new dam after the strengthening measures devised by the Central Water Commission, the highest technical body in the government of India, have been carried out that too with the concurrence of the engineers of the Government of Kerala at every stage.

As one closely associated with this dam and the strengthening measures undertaken, I am pained to see the controversies being raised on its safety, in spite of the wise opinion given by several experts who have inspected the dam and the Supreme Court having accepted the opinion of the experts.

(A. Mohanakrishnan, who has been handling inter-state river water issues on behalf of the Tamil Nadu government, is advisor (water resources) to the government.)