For years, the Pallikaranai swamp has embodied Chennai’s environmental paradox. One of the most important wetlands of Tamil Nadu, it is surrounded by apartment complexes, IT parks, main roads and neighborhoods that have grown steadily over the last five decades. Today, the marsh is at the center of a debate – whether protecting it requires steady development throughout the surrounding landscape, or whether science can identify a more nuanced regulatory framework that protects the wetlands and recognizes the rights of those who legally own and have occupied these lands for decades.
ecological assets
Long before the IT corridors, apartment complexes and main roads spanning the southern suburbs, Pallikaranai was a vast wetland ecosystem. Once covering approximately 50 square kilometres, the freshwater marsh was connected to dozens of smaller wetlands, grasslands and scrub forests, which controlled the natural drainage of the area. According to the Tamil Nadu State Wetland Authority (TNSWA), sediment studies show that the swamp is at least 1,000 years old, while marine crustacean and mollusk subfossils indicate that it once had greater marine influence. Decades of urbanization, land reclamation and indiscriminate dumping have reduced it to a fraction of its original range. The remaining core area of about 698 hectares was notified as a reserve forest in 2007. Even in its small form, Pallikaranai remains one of the most important ecological assets of Chennai.
The swamp receives water from about 65 wetlands before draining into the Bay of Bengal through Okkiam Madavu and Kovalam creeks. Acting as the city’s natural sponge, it stores monsoon floodwaters, recharges the groundwater table, filters pollutants, and controls floods – services that have gained greater importance after the devastating Chennai floods of 2015.
Pallikaranai is one of the richest urban biodiversity hotspots of India. Official records show that it supports more than 175 species of birds, 50 species of fish and more than 100 species of plants, in addition to 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 surrounded by one of Tamil Nadu’s fastest-growing urban landscapes. Yet the ecological value of the marsh has always been present, along with competitive pressures. Encroachment, pollution, infrastructure expansion and rapid urbanization have continuously changed the landscape around it.
In 2022, Pallikaranai received international recognition when an additional 550 hectares of the surrounding 698 hectares reserve forest were included under the Ramsar Convention. This took the total protected area to 1,247.54 hectares. Contrary to popular belief, Ramsar designation does not automatically prohibit construction or development. Rather, it recognizes the international ecological importance of a wetland and expects governments to ensure its “wise use” through scientific management.
Under the Wetlands (Conservation and Management) Rules of India, 2017, the next step after such recognition is for the State Wetland Authority to scientifically delineate the boundaries of the wetland, prepare an Integrated Management Plan (IMP) and identify the ‘influence zone’ – the surrounding landscape whose hydrology, drainage, groundwater movement and land use directly affect the ecological health of the wetland.
The IMP is expected to be based on hydrological and ecological studies, field validation and public consultation before finalizing regulatory measures. Unlike many Ramsar wetlands located away from dense human settlements, Pallikaranai is located in the middle of a metropolitan landscape. Over several decades a thriving economy of residential colonies, IT parks, hospitals, educational institutions, metro rail corridors and government offices has emerged around it, and statutory approvals have been issued by public authorities.
caught in the field
In September 2025, the southern bench of the National Green Tribunal (NGT) directed authorities not to grant planning approval or construction permission within one kilometer of the Pallikaranai Ramsar site until a comprehensive scientific study identifying the impact area of the wetland is completed.
Acting on the order, the Chennai Metropolitan Development Authority (CMDA), through a circular issued on October 3, 2025, directed planning authorities not to process applications within the Ramsar site and its proposed one-kilometre impact zone.
The notified area extends to parts of Perumbakkam, Sholinganallur, Medavakkam, Madipakkam, Thoraipakkam and Velachery. It also includes major public institutions such as the National Institute of Wind Energy, National Institute of Ocean Technology, ELCOT, metro rail infrastructure, hospitals, schools and government offices. The CMDA order has affected thousands of residents living in the fastest growing areas of Chennai.
Ganesh, a resident of Ram Nagar North since the 1980s, said his family vacated their 40-year-old independent house on a 2,400-square-foot plot to reconstruct it, but the CMDA order halted their plans. “The house was old, so we wanted to renovate it. But the moratorium on new approvals foiled our plans. After living here for more than four decades, it was emotionally difficult to move out because of the uncertainty,” he said.
He said his father had purchased the residential plot in the 1980s when there were few houses in the area and the nearest bus service was in Velachery.
Others point out that much of the development around the swamp took place with government approval over several decades. Chandran, who had purchased a plot in Madipakkam in 1994 based on the layout approved in 1964, said he had taken building permission from the then Chitlapakkam panchayat union before constructing his house. “People invested their lifetime savings after obtaining all the necessary permissions. Now they are unable to construct, modernize, renovate their properties or even take loans,” he said.
Property market affected
Residents also say that uncertainty has started to affect the local property market. Pawan, a resident of Thoraipakkam, said buyers have been wary of investing in the area despite its proximity to the old Mahabalipuram Road, the major IT park and the upcoming metro rail line. Rengasamy, representing residents of Ram Nagar North, Srinivas Nagar, Bagireddy Nagar, Ramalinga Nagar, Annai Theresa Nagar and surrounding areas, estimated that more than 3,000 residents were affected by the plan approval suspension. He said homeowners were unable to reconstruct old buildings, add floors or avail housing loans despite living in neighborhoods with established civic infrastructure such as roads, drinking water supply and underground sewerage.
This concern has been expressed by residents’ welfare associations. Federation of Thoraipakkam Residents Welfare Association president A. Francis said residents are not opposed to restoring the wetlands. He said, “We have campaigned for years to restore Pallikaranai and remove the Perungudi dump yard. But conservation should not be at the expense of millions of people living in already sanctioned neighbourhoods.”
S. of Federation of Velachery Residents Welfare Association. Kumararaja said he had recently failed to get approval for a joint venture redevelopment proposal in Velachery despite repeated attempts. “The government is losing crores of rupees in revenue. Velachery and Adyar sub-registrar offices used to get around ₹10,000 crore annually from registration alone, while the Greater Chennai Corporation (GCC) and CMDA are also losing income from property tax and planning permissions,” he said. However, wetland ecologists caution that the debate cannot be limited to property rights alone. The ecological health of Pallikaranai depends not only on the marsh but also on the surrounding landscape. The term ‘zone of influence’ means that activities outside the wetland can have an impact on activities inside it, said Jayashree Venkatsan, managing trustee of Care Earth Trust. He said, “Imagine a clean house surrounded by garbage. Eventually, dust and debris will enter the house. Similarly, if the hydrology around the swamp is altered, the swamp itself may no longer be healthy.”
He said maintaining feeder channels, drainage routes, freshwater flow, tidal exchange and seasonal water retention was important for the survival of the wetland. “Pallikaranai functions as a landscape, not just an isolated protected patch. Therefore, the impact zone must be delineated very carefully; otherwise, decades of conservation work may be undone.”
‘Demarcation continues’
According to the CMDA, the impact zone of one kilometer is unreasonable and has stopped real estate development in the key IT corridors of Old Mahabalipuram Road and East Coast Road. TNSWA says the one kilometer impact zone should not be seen as a permanent regulatory limit. Principal Chief Conservator of Forests (head of the forest force) and Member Secretary, TNSWA Srinivas R. Reddy said the current one kilometer zone was adopted as an interim precautionary measure based on the best information available at that time and should not be taken as a scientifically determined buffer. “A zone of one kilometer was proposed based on the information available at that time. This is a temporary precautionary demarcation and not a scientifically established final boundary,” he said.
Mr Reddy explained that the Ramsar designation is only one step in the conservation process. While international recognition was granted 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 exact extent of the wetland and its ecological characteristics. Only then will the impact area be determined,” he said.
The district administration is verifying survey numbers, land ownership and land-use records before forwarding the information to the National Center for Sustainable Coastal Management (NCSCM), which will conduct scientific verification of the wetland extent and recommend the final zone of impact. TNSWA says the purpose of this process is to ensure that the final notification is based on scientific evidence rather than broad assumptions. However, for residents, uncertainty has persisted for almost a year. Many say they are unsure whether they will ultimately be allowed to build, redevelop, mortgage or even sell properties that were purchased legally and in many cases developed with approvals given by public authorities decades ago.
