The dam’s waters have been going to Tamil Nadu’s thirsty southern districts for over a century. It has helped turn some 17 lakh acres of arid land in the rain shadows into green farms, erased memories of once-frequent famines and deep penury, even checked the migration of the hopeless to Sri Lanka. An 1895 agreement, which the British holding the then Madras province signed with the local Maharaja of Travancore, allows Tamil Nadu to have ‘all the water’ from the dam, till year 2894.

But the catch is, the dam is in Kerala, and so is the river feeding it. And it has been wanting both back. No matter if its own government had re-validated the original agreement in 1970 with no substantial changes, which has been condemned as a big blunder since.

Kerala, with 44 rivers of all sizes famously crisscrossing it and a lot of rain, had started realising that its own profligacy was inviting a steady water crisis, only by the late 1970s. Power crunches were common — its mainstay hydropower projects often don’t have sufficient water to make enough electricity. Idukki, where the Mullaperiyar dam is, accounts for about three-fourth of the state’s power output, and the state’s biggest hydro-power project is downstream of Mullaperiyar, with a holding capacity of around seven times more than that of the old dam, whose waters go to Tamil Nadu. And Kerala needs to produce at least 1000 MW more power in the coming years just to cope, while there’s not enough water at hand to meet even half the actual requirements of the state’s 82 lakh power consumer base.

But power or water crisis had seldom figured in Kerala’s public posturing in the issue since 1979, when it first aired apprehensions that the old Mullaperiyar dam could burst, pointing to visible seepages. It held up the scary spectre of lakhs of people in adjacent Kerala districts going under the deluge if that happened, and got MG Ramachandran, matinee-idol-turned chief minister of Tamil Nadu, to lower the dam’s water level from 152 to 136 feet. But some 104 feet of the dam’s water is dead storage, and lowering the level was later found to have hit farming in about 8000 hectares in Tamil Nadu, leading to an expected political uproar.

Tamil Nadu had to go about strengthening the dam at its own cost — it has since spent about Rs 20 crore on it — and the Central Water Commission certified it safe, after directing the level be reduced to 136 feet till the work was over, before upping it to 152 feet. But Kerala wanted the water level back at 136 feet, its successive governments crying havoc each time this mark was breached. No such masonry dam, Kerala argued, can safely outlive a lifespan of 50 to 60 years maintaining full capacity, and Mullaperiyar is a catastrophe in waiting.

Janata Party’s Subramaniam Swamy took it up to the Supreme Court and so did the Tamil Nadu government, and a Kerala NGO. In February this year, the SC told Tamil Nadu to raise the level to 142 feet, largely anchoring its verdict on the CWC’s safety certificate. The court, in fact, said that even if Mullaperiyar burst, the Idukki dam 50 kilometres downstream was quite capable of taking the additional water, and also declined to look at a subsequent review petition from Kerala, even chiding Kerala for its ‘obstructionist’ stance.

But Kerala didn’t take that lying down, and its assembly went on to unanimously pass a bill, the Kerala Irrigation and Water Conservation (Amendment) Bill 2006, empowering a government-appointed Dam Safety Authority to have the final say about the safety of the state’s 22 major and minor dams. An all-party meeting came to a rare consensus in Kerala that the government should do the spadework to build a new Rs 350-crore plus dam, and junk the agreement with Tamil Nadu to draw up a new one. The new dam idea, in fact, had been hanging fire for many years now, through the row.

Kerala’s bill had spelt out the maximum permissible water levels for all dams, and the ceiling was put at 136 feet for Mullaperiyar. The bill gave the Dam Safety Authority, headed by a former judge, the power to direct any “custodian” of any dam to suspend the functioning of the dam, or even decommission it if it is found to be a safety threat. The custodian, for Mullaperiyar, is the Tamil Nadu government, but the Authority has not yet begun flexing its muscle.

But such legislative manoeuvring in inter-state water wars hasn’t always been foolproof. Down south itself, the Cauvery Water Disputes Tribunal had asked Karnataka to release 205 thousand million cubic feet of water to Tamil Nadu, and Karnataka made an ordinance, later adopted as an Act, voiding the Tribunal’s order. The Supreme Court did not take long to declare the ordinance unconstitutional.

Not very different was the case of the Sutlej-Yamuna canal row when the Supreme Court directed the centre to take over construction of a portion of the canal in Punjab. The SC rejected Punjab’s review petition, and the Punjab Assembly quickly legislated to junk the 1981 agreement that the state had with its neighbours on sharing of river waters. The issue is still in court.

Anyway, the Kerala-Tamil Nadu stand-off now is deteriorating to a highly emotive issue, leaving lakhs of people on each side with sharply different stakes in it. Almost every political outfit of consequence in Tamil Nadu is rallying around the issue, leaving little elbowroom for M. Karunanidhi’s DMK government to negotiate. Not different is the predicament of his Kerala counterpart, V.S. Achuthanandan, who cannot afford to back down from the state’s 27-year-old position in the issue.

But while both sides are keeping up an effective din and getting proactive - people in Tamil Nadu are blocking most roads to Kerala, and the Kerala government is calling up the army and airforce to prepare for the projected catastrophe, and is even getting the navy to dive deep and look for chinks in the dam’s underwater — a key question remains.

Kerala has been holding up the dam’s threat potential, but what really is the threat potential? Though it has accused Tamil Nadu of attempting to shield the truth by preventing even naval divers from looking up the dam’s submerged parts, the fact is that the only scientific study that Kerala can claim to support its claim is one by the government-owned Centre for Earth Science

Studies, which says the dam could burst if an earthquake over 6 on the Richter scale hits it real close. The state hasn’t had a quake that big yet.