Scrap Mamallan reservoir, thousands write to CM Vijay

CHENNAI: More than 50 organisations and 1,161 citizens, including resident associations, fishers, researchers, conservationists, urban planners, have written to Chief Minister C Joseph Vijay urging the State government to scrap the proposed Mamallan Reservoir in the Kovalam-Nemmeli backwaters, citing flood risks, loss of fishing livelihoods and damage to the coastal wetland.

The Water Resources Department has proposed the reservoir across 6,950 acres in two phases. The groups say the project would alter a much larger coastal wetland that functions as a natural floodplain and coastal buffer.

The most significant concern is the project’s impact on the natural movement of floodwater. According to the representation, Phase I covers 4,375 acres of floodplain, with a 13-km catchment proposed to be diverted through a 200-metre inlet and a 70-metre-wide canal.

The petitioners have warned that this could increase flooding in parts of Kelambakkam, Tiruporur, Vengaleri and other upstream areas, particularly when the reservoir is already holding water and cannot accommodate sudden inflows.

The Kovalam-Nemmeli wetland is a brackish, tidally influenced ecosystem extending from the Muttukadu estuary towards Kokilamedu. The representation stated that the wetland served as a buffer against storm surges, coastal erosion and other extreme events. It cited the State’s 2024-coastal climate assessment, which classified Chengalpattu’s coastal climate risk and cyclone-track proximity as ‘very high’.

“For over 20 years, OMR residents have paid taxes and watched pipelines pass right through our corridor while our own taps remain dry. Now, we’re offered the disastrous Mamallan reservoir – a project that will encroach on the Kovalam-Nemmeli salt marsh, and destroy a critical habitat for over 200 resident and migratory bird species, robbing livelihoods, eroding biodiversity and exposing residents to floods. This is not sustainable water planning,” lamented Harsha Koda, co-founder, Federation of OMR Residents’ Associations (FOMRRA).

Narayanan, a fisherman from Kovalam, said that the backwater was particularly important for prawn fishing, which requires little investment and is accessible even to elderly people who cannot venture into the sea. “There has been no income for seven months since the beginning of this project,” he said. “The impact will extend beyond Kovalam, as fishers from several villages depend on the backwater.”

The representation also pointed out that thousands of people from 16 fishing villages, besides Irular and other inland fishing communities, depended on the wetland for prawns and crabs. It argued that replacing these natural fishing grounds with artificial infrastructure would destroy an existing livelihood system. It cited a habitat assessment that recorded 45,000 birds belonging to 102 species, while claiming that the wider wetland supported more than 200 species, including migratory birds and painted storks.