For years, the Pallikaranai marsh has embodied Chennai’s environmental paradox. One of Tamil Nadu’s most important wetlands, it is also surrounded by apartment complexes, IT parks, arterial roads, and neighbourhoods that have grown steadily over the past five decades. Today, the marsh is at the centre of a debate — whether protecting it requires freezing development across the entire surrounding landscape, or whether science can identify a more nuanced regulatory framework that safeguards the wetland while recognising the rights of people who have legally owned and occupied these lands for decades.
Ecological asset
Long before the IT Corridor, apartment complexes, and arterial roads spread across the southern suburbs, Pallikaranai was an expansive wetland ecosystem. Once stretching across nearly 50 square kilometres, the freshwater marsh connected dozens of smaller wetlands, grasslands, and scrub forests, regulating the region’s natural drainage. According to the Tamil Nadu State Wetland Authority (TNSWA), sediment studies suggest the marsh is at least 1,000 years old, while marine crustacean and mollusc sub-fossils indicate it once had greater marine influence. Decades of urbanisation, land reclamation, and indiscriminate dumping have reduced it to a fraction of its original extent. The remaining core area of around 698 hectares was notified as a Reserve Forest in 2007. Even in its diminished form, Pallikaranai remains one of Chennai’s most critical ecological assets.
The marsh receives water from nearly 65 wetlands before draining into the Bay of Bengal through Okkiyam Madavu and Kovalam Creek. Acting as the city’s natural sponge, it stores monsoon floodwaters, recharges the groundwater table, filters pollutants, and moderates flooding — services that have assumed greater significance after the devastating Chennai floods of 2015.
Pallikaranai is also one of India’s richest urban biodiversity hotspots. Official records show it supports more than 175 species of birds, 50 species of fish, and over 100 species of plants, besides reptiles, amphibians, mammals, butterflies, and molluscs. Every winter, migratory birds such as Glossy Ibis, Eurasian Spoonbill and Pheasant-tailed Jacana descend on the marsh, underscoring its ecological importance despite being enveloped by one of Tamil Nadu’s fastest-growing urban landscapes. Yet the marsh’s ecological value has always existed alongside competing pressures. Encroachment, pollution, infrastructure expansion, and rapid urbanisation have steadily transformed the landscape around it.
In 2022, Pallikaranai received international recognition when an additional 550 hectares surrounding the 698-hectare Reserve Forest was included under the Ramsar Convention. This took the total protected area to 1,247.54 hectares. Contrary to popular perception, a Ramsar designation does not automatically prohibit construction or development. Rather, it recognises a wetland’s international ecological importance and requires governments to ensure its “wise use” through scientific management.
Under India’s Wetlands (Conservation and Management) Rules, 2017, the next step after such recognition is for the State Wetland Authority to scientifically delineate the wetland’s boundaries, prepare an Integrated Management Plan (IMP), and identify a ‘zone of influence’ — the surrounding landscape whose hydrology, drainage, groundwater movement, and land use directly affect the wetland’s ecological health.
The IMP is expected to be based on hydrological and ecological studies, field verification, and public consultation before regulatory measures are finalised. Unlike many Ramsar wetlands located away from dense human settlements, Pallikaranai sits in the middle of a metropolitan landscape. A thriving economy of residential colonies, IT parks, hospitals, educational institutions, Metro Rail corridors, and government offices has emerged around it over several decades, and statutory approval has been issued by public authorities.
Caught in the zone
In September 2025, the Southern Bench of the National Green Tribunal (NGT) directed the authorities not to grant planning approval or construction permission within one kilometre of the Pallikaranai Ramsar site until a comprehensive scientific study identifying the wetland’s zone of influence was completed.
Acting on the order, the Chennai Metropolitan Development Authority (CMDA), through a circular issued on October 3, 2025, instructed the planning authorities not to process applications within the Ramsar site and its proposed one-kilometre zone of influence.
The notified area extends across parts of Perumbakkam, Sholinganallur, Medavakkam, Madipakkam, Thoraipakkam, and Velachery. It also encompasses major public institutions such as the National Institute of Wind Energy, the National Institute of Ocean Technology, ELCOT, Metro Rail infrastructure, hospitals, schools, and government offices. The CMDA order has affected thousands of residents living in Chennai’s fastest-growing neighbourhoods.
Ganesh, a resident of Ram Nagar North since the 1980s, said his family vacated their 40-year-old independent house on a 2,400 sq. ft. plot to rebuild it, but the CMDA’s order stalled their plans. “The house had become old, so we wanted to rebuild it. But the bar on new approval dampened our plans. Having lived here for over four decades, moving out due to the uncertainty was emotionally difficult,” he said.
His father bought the residential plot in the 1980s when the area had few houses and the nearest bus service was at Velachery, he added.
Others point out that much of the development around the marsh had taken place with government approval over several decades. Chandran, who bought a plot at Madipakkam in 1994 based on a layout approved in 1964, said he obtained building permission from the then Chitlapakkam Panchayat Union before constructing his house. “People invested their life savings after obtaining all the necessary permissions. Now they are unable to build, modernise, renovate, or even raise loans against their properties,” he said.
Property market affected
Residents also say the uncertainty has begun affecting the local property market. Pavan, a resident of Thoraipakkam, said buyers have become wary of investing in the area despite its proximity to Old Mahabalipuram Road, major IT parks, and the upcoming Metro Rail line. Rengasamy, representing residents of Ram Nagar North, Srinivasa Nagar, Bagireddy Nagar, Ramalinga Nagar, Annai Theresa Nagar, and adjoining localities, estimated that more than 3,000 residents had been affected by the planning approval suspension. He said homeowners were unable to reconstruct ageing buildings, add floors, or access housing loans despite living in neighbourhoods with established civic infrastructure such as roads, drinking water supply, and underground sewerage.
The concern is echoed by residents’ welfare associations. A. Francis, president of the Federation of Thoraipakkam Residents’ Welfare Associations, said residents were not opposed to restoring the marshland. “We have campaigned for years to restore Pallikaranai and remove the Perungudi dump yard. But conservation should not come at the cost of lakhs of people already living in approved neighbourhoods,” he said.
S. Kumararaja, of the Federation of Velachery Residents’ Welfare Association, said he had recently failed to secure approval for a joint-venture redevelopment proposal at Velachery, despite repeated attempts. “The government stands to lose crores of rupees in revenue. Registration alone used to fetch nearly ₹10,000 crore annually from the sub-registrar offices across Velachery and Adyar, while the Greater Chennai Corporation (GCC) and the CMDA are also losing income from property tax and planning permissions,” he said. Wetland ecologists, however, caution that the debate cannot be reduced to property rights alone. The ecological health of Pallikaranai depends not only on the marsh but also on the surrounding landscape. The very term, ‘zone of influence’, means activities outside the wetland can have a bearing on what happens inside it, said Jayashree Vencatesan, managing trustee of Care Earth Trust. “Imagine having a clean house surrounded by garbage. Eventually, the dust and waste will enter the house. Likewise, if the hydrology around the marsh is altered, the marsh itself cannot remain healthy,” she said.
She added that maintaining feeder channels, drainage pathways, freshwater inflows, tidal exchange, and seasonal water retention was important to the wetland’s survival. “Pallikaranai functions as a landscape, not merely as an isolated protected patch. The zone of influence, therefore, has to be delineated very carefully; otherwise, decades of conservation work could be undone.”
‘Demarcation in progress’
According to the CMDA, the one-kilometre zone of influence is unjustified and has brought real estate development across the major IT corridors of Old Mahabalipuram Road and East Coast Road to a standstill. The TNSWA maintains that the one-kilometre zone of influence should not be viewed as a permanent regulatory boundary. Srinivas R. Reddy, Principal Chief Conservator of Forests (Head of Forest Force) and Member-Secretary of the TNSWA, said the current one-kilometre zone was adopted as an interim precautionary measure based on the best information available at the time and should not be construed as a scientifically determined buffer. “The one-kilometre zone was proposed based on the information available then. It is a temporary precautionary demarcation and not the final scientifically established boundary,” he said.
Mr. Reddy explained that the Ramsar designation is only one step in the conservation process. While the international recognition was accorded in 2022, the wetland must now be formally notified under the Wetlands (Conservation and Management) Rules, 2017, a process that requires detailed scientific studies before regulatory boundaries are finalised. “As part of this exercise, we will undertake scientific ground-truthing to identify the precise extent of the wetland and its ecological characteristics. Only then will the zone of influence be delineated,” he said.
The district administration is verifying survey numbers, land ownership, and land-use records before forwarding the information to the National Centre for Sustainable Coastal Management (NCSCM), which will carry out scientific validation of the wetland boundary and recommend the final zone of influence. The TNSWA maintains that this process is intended to ensure that the final notification is based on scientific evidence rather than broad assumptions. For residents, however, the uncertainty has persisted for nearly a year. Many say they remain unsure whether they will eventually be permitted to construct, redevelop, mortgage, or even sell properties that were purchased legally and, in many cases, developed with the approval granted by public authorities decades ago.
