What Happened
- A group of 22 leading scientists, including ecologists, ornithologists, coastal social scientists, and contributors to national and global climate assessments, have urged Tamil Nadu Chief Minister M.K. Stalin to withdraw the proposed Mamallan Reservoir Project.
- The reservoir, for which the foundation stone was laid on January 19, 2026, is proposed at Vada Nemmeli in the Kovalam basin as Chennai's sixth drinking water source and Tamil Nadu's first freshwater reservoir along the coast.
- The project, estimated at Rs 342.60 crore, covers land between Thiruvidanthai and Kokilamedu with a storage capacity of 1.65 thousand million cubic feet (TMC).
- Scientists warn that constructing a freshwater reservoir over the Kovalam-Nemmeli salt marsh would cause irreversible damage to one of Tamil Nadu's most critical coastal ecosystems.
- As an alternative, the scientists recommend declaring the salt marsh a protected coastal wetland under the name "Mamallan Lagoon" and initiating a science-based restoration programme.
Static Topic Bridges
Coastal Wetlands and Ecosystem Services
Coastal wetlands, including salt marshes, mangroves, mudflats, and estuaries, are among the most ecologically productive systems on the planet. They perform critical ecosystem services that are often undervalued in conventional cost-benefit analyses of infrastructure projects.
- Salt marshes support benthic invertebrates, serve as breeding grounds for commercially important fish and prawns, sustain migratory birds along flyway corridors, and protect coastlines from erosion and storm surges.
- Coastal wetlands sequester "Blue Carbon" at rates significantly higher than terrestrial forests. Mangrove and salt marsh sediments can store carbon for millennia, making their destruction a net contributor to greenhouse gas emissions.
- The Coastal Regulation Zone (CRZ) Notification, 2019, classifies coastal zones into four categories (CRZ-I to CRZ-IV), with ecologically sensitive areas like mangroves, coral reefs, and mudflats falling under CRZ-IA where no development is permitted.
- The Wetlands (Conservation and Management) Rules, 2017, under the Environment (Protection) Act, 1986, mandate that state governments identify and notify wetlands and prohibit activities like permanent construction, effluent discharge, and reclamation in notified wetlands.
Connection to this news: The Kovalam-Nemmeli salt marsh falls squarely within the type of coastal ecosystem that the CRZ framework and Wetlands Rules seek to protect. Scientists argue that converting this ecotone into a freshwater reservoir would destroy all ecological functions within a single season.
Ramsar Convention and India's Wetland Conservation
India is a signatory to the Ramsar Convention on Wetlands (1971), which it ratified on February 1, 1982. The Convention provides the framework for national action and international cooperation for the conservation and wise use of wetlands and their resources.
- India has 98 Ramsar sites covering 13,60,805.63 hectares as of January 2026, with 67 new sites added since 2014.
- Tamil Nadu has the highest number of Ramsar sites in India with 20 designated sites, reflecting the state's rich coastal and inland wetland heritage.
- The Ramsar Convention defines wetlands broadly to include "areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt."
- India's National Wetland Conservation Programme (NWCP) supports the conservation and management of identified wetlands, though enforcement remains a challenge at the state level.
- The "Wise Use" principle of the Ramsar Convention requires that wetland utilization is compatible with maintaining their ecological character.
Connection to this news: The scientists' proposal to designate the Kovalam-Nemmeli salt marsh as "Mamallan Lagoon" under protected status aligns with India's Ramsar obligations and Tamil Nadu's existing leadership in wetland designation, offering a conservation-first alternative to the reservoir project.
Environmental Impact Assessment (EIA) and Development-Conservation Conflict
The EIA Notification, 2006, under the Environment (Protection) Act, 1986, mandates environmental clearance for specified development projects. The tension between urban water security and ecosystem preservation represents a recurring development-conservation conflict in India's environmental governance.
- The EIA process involves screening, scoping, public consultation, expert appraisal, and environmental clearance stages.
- Water supply projects, including reservoirs, typically require EIA clearance if they exceed threshold capacity limits set by the State Environment Impact Assessment Authority (SEIAA).
- The National Green Tribunal (NGT), established under the NGT Act, 2010, has jurisdiction over environmental disputes including those involving wetland destruction, CRZ violations, and inadequate EIA processes.
- Article 48A (Directive Principle) mandates the State to protect and improve the environment and safeguard forests and wildlife, while Article 51A(g) (Fundamental Duty) obligates citizens to protect the natural environment.
- The Precautionary Principle, recognized by the Supreme Court in Vellore Citizens Welfare Forum v. Union of India (1996), requires that environmental protection measures must anticipate, prevent, and address causes of degradation rather than react after damage occurs.
Connection to this news: The scientific community's intervention invokes the precautionary principle, arguing that the irreversible destruction of a functioning salt marsh ecosystem cannot be justified when alternative water supply solutions exist, and that the project requires rigorous environmental scrutiny before proceeding.
Key Facts & Data
- Project cost: Rs 342.60 crore.
- Storage capacity: 1.65 TMC (thousand million cubic feet).
- Number of scientists who signed the letter: 22 (ecologists, ornithologists, coastal social scientists, climate assessment contributors).
- Foundation stone laid: January 19, 2026.
- Location: Kovalam basin, between Thiruvidanthai and Kokilamedu, Vada Nemmeli.
- India's Ramsar sites: 98 (as of January 2026); Tamil Nadu: 20 (highest among Indian states).
- CRZ Notification: 2019 (latest revision); Wetlands Rules: 2017.