2 days Ago By Omjasvin M D
Chennai: Having choked River Cooum to death by rampant discharge of untreated sewage and turning a blind eye to encroachments, Chennai is repeating all these mistakes to take life out of Cooum's cousin – River Kosasthaiyar – which drains one-third of Chennai's water. As of now it has still some life left and it is not too late for the govt and its agencies such as the Chennai Rivers Restoration Trust (CRRT) and the Water Resources Department (WRD) to step in and save it. The CRRT has failed to propose any worthwhile project for the river for two decades now, despite spending several hundred crores of rupees for Adyar and Cooum.
"Till Manali, the river is relatively free from heavy sewage and obstructions. Reviving the floodplains here, especially in areas like Nappalayan and Vallur, could significantly increase the river's capacity. Downstream, a sewage interceptor with decentralised treatment plants could be built to tackle the pollution from Buckingham Canal," said T Kanthimathinathan, state disaster management coordinator.
He added that nearly 50,000 encroachments need to be removed from the North B Canal. Experts also stress the need to focus on the estuary, where salt pans, mangroves, wetlands, and native species have all perished. Ennore's wetland area has shrunk from 877 hectares in 1996 to just 277 hectares in 2022, according to submissions to the National Green Tribunal (NGT).
Running to 136 km from Andhra Pradesh's Ammapalli Dam, Kosasthalaiyar had a brush with disaster twice last year alone: an oil spill that polluted the estuary up to Manali and a severe flooding in Dec 2023, when a bund breach submerged Manali, affecting nearly 1 lakh residents. Yet, no restoration efforts have been made. The river's drainage capacity below Manali stands at a meagre 20,000 cusecs.
A spot visit by TOI revealed over 1,000 encroachments along Manali's Sadayankuppam area, crowding the river's floodplains, with no flood barrier walls in place. The encroachments have reduced the river's carrying capacity from 1.1 lakh cusecs to just 60,000 cusecs beyond Manali.
Last year's breach occurred with only a 40,000 cusec release from Poondi, submerging roads to Ennore Port and halting truck traffic. The river's surplus channel, stretching from the Thamaraipakkam Dam near Poondi to Cholavaram and Puzhal, is also neglected. There are no boundary walls at Madhavaram, Mathur, or along the 200-feet bypass road in Manali, and sewage continues to seep into the water.
Downstream in the Ennore Estuary, high levels of pollution from fly ash and industrial chemicals have rendered the area lifeless. Dredging has not been carried out in over a decade at the estuary, with a half-submerged, rusted dredging machine near Mugathwarakuppam serving as a grim reminder. While some dredging has been done at Kattukuppam, the extracted mud piled high is ash-grey, underscoring the river's heavy pollution.
Further downstream, yellow and brown chemicals continue to pour into the water near the Buckingham Canal, where sewage and industrial waste from over a dozen factories — many of them encroaching on the river's floodplains — are dumped unchecked. Despite its dire state at the estuary, experts believe Kosasthalaiyar has better restoration prospects than Chennai's other rivers like the Adyar, Cooum and the Buckingham Canal, thanks to its concentrated pollution sources. Most of the contamination begins beneath the North Buckingham Canal, which drains 10,000 cusecs of floodwater from areas like Tondiarpet, Thiruvottiyur, and Kodungaiyur.
Watersheds like Ambattur, Korattur, and Retteri lakes also feed into the river, alongside the Kodungaiyur and Otteri Nullah waterways. Santha Sheela Nair, a member of the river restoration expert committee, said hefty penalties collected by the Tamil Nadu Pollution Control Board from polluting industries should be redirected towards restoration efforts, particularly targeting fly ash and chemical pollutants. "The surrounding environment and livelihoods that depend on the river are in ruins.
We need immediate action, and we will see changes," she urged. Joint Chief Engineer of the Water Resources Department, C Podupanithilagam, added that plans are in place to construct four reservoirs near Poondi to conserve more water. "Work is underway.
After the last floods, we recommended building revetment walls and have blocked sewage drains in Manali. A detailed project report on the downstream restoration, prepared by the NGT expert committee, will be released soon," he said. MSID:: 113433715 413 |.
