Published Feb 16, 2026 | 12:02 PM ⚊ Updated Feb 16, 2026 | 12:02 PM
Ongoing works for Mamallan Reservoir Project. (HECS)
Synopsis: A group of 22 leading scientists and contributors to national and global climate assessments urged Tamil Nadu Chief Minister MK Stalin to abandon the proposed Mamallan Reservoir Project. Converting this ecotone into a freshwater reservoir would, they cautioned, destroy all these ecological functions within a single season.
A group of 22 leading scientists, including ecologists, ornithologists, coastal social scientists, and contributors to national and global climate assessments, urged Tamil Nadu Chief Minister MK Stalin to abandon the proposed Mamallan Reservoir Project, sources said on Monday, 16 February.
In a letter addressed to the chief minister and Additional Chief Secretary (Environment, Climate Change and Forests) Supriya Sahu, the scientists warned that constructing a drinking water storage facility over the Kovalam–Nemmeli salt marsh would cause irreversible damage to one of the state’s most critical coastal ecosystems.
Salt marshes, the scientists noted, support benthic invertebrates, serve as breeding grounds for fish and prawns, sustain migratory birds, and protect coastlines from erosion and storm surges.
Converting this ecotone into a freshwater reservoir would, they cautioned, destroy all these ecological functions within a single season.
As an alternative, the scientists have recommended that the state declare the salt marsh a protected coastal wetland under the name “Mamallan Lagoon” and initiate a restoration programme grounded in robust scientific research and the deep spatial knowledge of local communities.
Such an approach, they said, would honour Tamil Nadu’s ecological heritage and its long-standing traditions of sustainable water management.
Proposing it as Chennai’s sixth drinking water source, Stalin laid the foundation stone for the Mamallan reservoir on 19 January at Vada Nemmeli, on East Coast Road. He had said that it would be the state’s first freshwater reservoir along the coast.
The project, estimated at ₹342.60 crore, in the Kovalam basin, covers the land parcel between Thiruvidanthai and Kokilamedu, and would be implemented by the Water Resources Department (WRD) to create the reservoir spread over 5,161.27 acres and with a storage capacity of 1.65 thousand million cubic feet (TMC).
The reservoir is projected to have an annual storage capacity of 2.25 TMC when filled twice and a potential to supply 170 million litres a day (mld) to Chennai.
(With inputs from Subash Chandra Bose.)
