KOCHI: Flushing out huge quantities of sediments from the Kallarkutty reservoir in Idukki district about a fortnight ago down the Periyar has raised concern of safety and quality of drinking water in Kochi and nearby towns and panchayats in the coming days.

Water to these areas is supplied from the treatment plant at Aluva. Already, water supply has been affected in several upstream panchayats of the Periyar. In some of these panchayats, drinking water is now being supplied through tankers. (The Kerala State Electricity Board, which was responsible for the untimely opening of the Kallarkutty dam, has offered to foot the bill for water supply in these panchayats.) Scientists and environmentalists, who complain that the authorities have yet to gauge the after-effects of the flushing out operation, have called for immediate steps to check contamination. On Friday, the High Court, on a writ petition by the Committee Against Contamination of the Periyar, asked the Government to explain the circumstances in which the reservoir was flushed out. The court has set Thursday as the deadline for the Government to report back.

C.M. Joy, botanist and general secretary of River Conservation Society, has warned that the massive inflow into the Periyar of silt, that had been accumulated in the reservoir over a dozen years and turned into decomposed organic matter, might lead to `eutrophication.'

Eutrophication, which is the outcome of an increase of nitrates, phosphates and biodegradable waste, usually occurs in lakes and stagnant waterbodies. This would cause `algal bloom,' reduction in oxygen content in water and growth of bacteria. This would lead to change in the colour, taste and odour of water. "If industrial effluents are let into this water, which happens quite often in the Edayar industrial belt, Periyar water will be unfit for drinking for weeks together and several lakhs of people will be affected," Dr. Joy said.

Because of the damage to the riverbed caused by sand-mining, the river level is lower than the sea level and hence water level has drastically slowed. This has created the situation of stagnation of the river downstream from Aluva, he pointed out.

To pre-empt eutrophication, Dr. Joy said, the authorities should step up inflow and stabilise the pH factor and oxygen content in the river. The KSEB has already offered to let out water from the Idamalayar dam in order to scale up flow in the Periyar and wash the silt down to the sea. For this, Dr. Joy said, the Paathalam bund, close to the river mouth, would have to be broken.

Dr. Chandramohan of Cochin University, who collected samples from the Peiryar to study the impact of the Kallarkutty silt's mixing with the river water, said draining out the silt through the Paathalam bund should be carried out very carefully to prevent the flow back of seawater and getting mixed with the river water, which would hit drinking water supply.

Purushan Eloor, environmentalist, said the authorities should quickly take crisis management steps lest there should be a water crisis and health crisis in the towns and villages as well as Kochi city which rely on the Periyar for drinking water.

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