The unpolluted stretch of Cooum River is set to get one more check dam at Perambakkam in Tiruvallur district. However, residents have raised concerns over discharge of sewage and urged the State government to ensure that the check dams do not turn into sewage discharge points.

The Water Resources Department (WRD) has started the process to construct the check dam — a storage structure that will retain floodwater and boost groundwater table. It will come up around 7.7 km downstream of Kesavaram anicut at a cost of ₹6.50 crore.

Many check dams across the Cooum in Tiruvallur have retained water even during summer. This has encouraged the WRD to chalk out plans to build more storage structures for recharging groundwater and preventing floods in Chennai.

Officials said that the check dam, across the 85-metre-wide river, would have a design to discharge nearly 10,556 cubic feet of water per second (cusecs) and a storage capacity of nearly 6.74 million cubic feet of water (mcft), when filled twice a year.

“This check dam will retain water in the Cooum for a length of 1.4 km, help irrigate about 360 acres of land and recharge borewells that are used to supply drinking water…,” an official said.

The WRD is set to start the work in May or early June, and complete it in a year. Welcoming the efforts to build more check dams across the river, residents said that the check dams too were not spared of sewage discharge in fast-urbanising areas.

K. Mugundhan, co-ordinator, Unpolluted Cooum Protection Committee, said that residents of Soranchery and Anaikattucherry benefited from the new check dam near Soranchery for irrigation and drinking water needs. However, a check dam along Kaduvetti village near Paruthipattu had become vulnerable to sewage discharge. “It is important for government agencies to ensure that check dams do not become sewage discharge points of nearby local bodies,” he added.

Officials of the WRD said they were coordinating with the local bodies to address the issues.