Chennai: What was once a freshwater source for farmers has turned into a cesspool, with untreated sewage discharged into the canal leading to Thangal Lake near Nedungundram by about 20 lorries every night. This has raised concerns over pollution, groundwater contamination and recurring flooding in nearby residential areas.The 35 acre lake in Puthur village, under Nedungundram village panchayat, is located about 5km from Tambaram Corporation limits. Residents said sewage lorries discharge waste from surrounding areas into the canal — which flows into the lake — instead of taking it to the sewage treatment plant (STP) in Tambaram.The most affected areas are Puthur, Sri Sai Avenue, Perumalpuram, Mappedu, Krishna Nagar, and Bharathidasan Nagar, where about 10,000 residents live. They say the dumping has worsened the pollution in the water body, and no effective action has been taken despite complaints to the district administration and panchayat officials.“Thangal lake was once fed by channels from Agaramthen lake and was used extensively by farmers in surrounding areas. Now it has been affected by sewage dumped by households and by a canal which was constructed by highways department to prevent flooding. The canal carries untreated sewage from more than 3,000 houses before it eventually enters the lake,” said S Murugan, a resident of Sri Sai Avenue, near Mappedu. He added, “In Feb this year, a large number of fish were found floating dead in the lake. The foul smell was unbearable and we are worried that the pollution could affect groundwater.”Residents said that despite rapid real estate development, the locality lacks an adequate stormwater drain network. “Every time it rains heavily, sewage and rainwater mix in the lake, which overflows and floods our homes. The drains constructed this year are not sufficient to handle the water,” said M Pallavai, a resident of Puthur.Darwin Annadurai, environmental activist and founder of Eco Society of India, said, “Untreated sewage will kill fish and other aquatic creatures. It also affects groundwater quality. Continued discharge can disturb the lake’s natural ecosystem, reduce water quality and make the waterbody unsuitable for aquatic life.”M Venkataragavan, block development officer, St Thomas Mount, said, “The lake and surrounding area will be inspected and necessary action will be taken against the illegal sewage discharge into the lake.”
