UNDER WAY: Work in progress to build a check dam across the Adyar river at Nandambakkam. — Photo: A. Muralitharan

TAMBARAM: Imagine a two-km long, 125-metre wide reservoir of fresh rainwater in Chennai. Considering the present state of the waterways and efforts to conserve rainwater, it may be a tall order. However, it might be a reality by the next monsoon once the check dam across the Adyar River at Nandambakkam is completed.

The construction of the check dam across the Adyar by the Public Works Department (PWD) started in August and was expected to be completed by April 2006. The Rs. 3.25-crore project is funded by the Chennai Metropolitan Water Supply and Sewerage Board under the Chennai Water Supply Augmentation Project-II.

Under the project, it has been planned to construct check dams, reservoirs and percolation tanks to store surplus water in order to enhance recharge in the Kosastalaiyar, Cooum, Adyar and Palar, according to official sources. It was decided to construct four check dams across the Adyar at Anakaputhur, Gowl Bazaar, Manapakkam and Nandambakkam at a cost of Rs. 12.37 crores.

Once completed, the check dam at Nandambakkam is expected to harness 16.62 million cubic feet of water (approximately 470 million litres). The main purpose behind constructing the check dam is to conserve rainwater that would, in turn, help in recharging groundwater in the vicinity of the check dam.

The check dam would be 125 m wide and 1.5 m in height and would help to limit the draining of water from the Adyar into the Bay of Bengal. During monsoons, a reservoir of water to a length of about two kilometres behind the check dam would be created. The riverbed was not being deepened and there was no possibility of inundation anywhere near the check dam, officials said.

However, there is cause for concern: discharge of domestic sewage and industrial waste into the Adyar. Officials admit contamination of the conserved rainwater near the check dam would spoil the quality of groundwater, defeating the purpose .

Apart from houses letting out grey water into the river, untreated effluents from tanneries found their way into it. Moreover, some of the local bodies along the banks of the river were also guilty of discharging untreated sewage into the river.

Pointing out that about 40 lakes and tanks emptied their surplus water into the Adyar, members of Exnora said the river would go a long way in reducing the water problems of the southern fringes of Chennai. And construction of the check dam would make it mandatory for the Government to ensure discharge of sewage and effluents into the Adyar was completely stopped, the activists said.

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