Quicksand in Chennai’s Pallikaranai Swamp
For years, the Pallikaranai marsh has epitomized Chennai’s ecological paradox. One of Tamil Nadu’s most important wetlands, it is also surrounded by housing complexes, IT parks, thoroughfares and neighborhoods that have grown steadily over the past five decades. Today, the marsh is at the center of debate—whether its protection requires a freeze on development of the entire surrounding landscape, or whether science can identify a more nuanced regulatory framework that protects the wetland while recognizing the rights of the people who have legally owned and occupied the land for decades.
Ecological property
Long before the IT corridor, housing complexes and highways spread across the southern suburbs, Pallikaranai was a vast wetland ecosystem. The freshwater marsh, which once covered nearly 50 square kilometers, connected dozens of smaller wetlands, grasslands, and scrub forests that regulated the region’s natural drainage. According to the Tamil Nadu State Wetland Authority (TNSWA), sediment studies indicate that the marsh is at least 1,000 years old, while subfossils of marine crustaceans and molluscs indicate that it once had a greater influence on the sea. Decades of urbanization, land reclamation and indiscriminate dumping have reduced it to a fraction of its original extent. The remaining core area of approximately 698 hectares was notified as reserve forest in 2007. Even in its reduced form, Pallikaranai remains one of Chennai’s most important ecological assets.
The swamp receives water from nearly 65 wetlands and then drains into the Bay of Bengal through Okkiyam Madavu and Kovalam Creek. It acts as the city’s natural sponge, storing monsoon floods, recharging the water table, filtering pollutants and mitigating floods – services that have gained greater importance following the devastating Chennai floods of 2015.
Pallikaranai is also one of the richest sites of urban biodiversity in 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, European pintail and jacana pheasant flock to the marshes, underscoring its ecological importance despite being surrounded by one of Tamil Nadu’s fastest growing urban landscapes. Yet the ecological value of the bog has always existed alongside competing pressures. Encroachment, pollution, infrastructure expansion and rapid urbanization have constantly transformed the landscape around it.
In 2022, Pallikaranai gained international recognition when an additional 550 hectares surrounding the 698 hectares of reserve forest were included in the Ramsar Convention. This increased the total protected area to 1,247.54 hectares. Contrary to popular opinion, the Ramsar designation does not automatically prohibit construction or development. Rather, it recognizes the international ecological importance of wetlands and requires governments to ensure their “wise use” through scientific management.
According to India’s Wetlands Conservation and Management Rules, 2017, the next step after such recognition is for the state wetlands 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 ecological health of the wetland.
The IMP is expected to be based on hydrologic and ecological studies, field verification, and public consultation before regulatory action is finalized. Unlike many Ramsar wetlands, which are located far from dense human settlements, Pallikaranai lies in the middle of a metropolitan landscape. Within a few decades, a thriving economy of residential colonies, IT parks, hospitals, educational institutions, metro corridors and government offices has sprung up around it and public authorities have issued statutory approvals.
Caught in the zone
In September 2025, the South Bench of the National Green Tribunal (NGT) ordered authorities not to grant planning approval or building permission within one kilometer of the Pallikaranai Ramsar site until a comprehensive scientific study identifying the wetland impact zone is completed.
The Chennai Metropolitan Development Authority (CMDA), acting on the order, through a circular issued on October 3, 2025, instructed planning authorities not to process applications in the Ramsar site and its proposed one kilometer impact zone.
The notified area is spread over Perumbakkam, Sholinganallur, Medavakkam, Madipakkam, Thoraipakkam and Velachery parts. It also includes large public institutions such as the National Wind Energy Institute, the National Institute of Ocean Technology, ELCOT, metro 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 had vacated their 40-year-old independent house on a 2,400-square-foot plot to rebuild it, but the CMDA order halted their plans. “The house was getting old, so we wanted to rebuild it. But the re-approval bar scuppered our plans. Having lived here for over four decades, moving was emotionally difficult because of the uncertainty,” he said.
His father bought a residential plot in the 1980s, when there were few houses in the area and the nearest bus service was in Velachery, he added.
Others point out that much of the development around the marsh has taken place with government approval over several decades. Chandran, who bought a plot in Madipakkam in 1994 based on a plan approved in 1964, said he had obtained planning permission from the then Chitlapakkam Panchayat union before constructing his house. “People invested their life savings after getting all the necessary permits. Now they can’t build, modernize, renovate or even get loans for their properties,” he said.
Real estate market affected
Residents also say the uncertainty has begun to affect the local real estate market. Pavan, a resident of Thoraipakkam, said buyers have become apprehensive about investing in the area despite its proximity to Old Mahabalipuram Road, major IT parks and the upcoming metro 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 were affected by the suspension of planning approvals. He said homeowners were unable to renovate aging buildings, add floors or access housing loans despite living in neighborhoods with established civic infrastructure such as roads, potable water supply and underground sewers.
Social associations of residents also echo the concerns. A. Francis, president of the Federation of Thoraipakkam Residents’ Welfare Association, said the residents were not against the restoration of the swamps. “For years, we have been campaigning for the restoration of Pallikaranai and the removal of the Perungudi landfill. However, protection should not come at the cost of millions of people who already live in the approved areas,” he said.
S. Kumararaja of the Federation of Velachery Residents’ Social Association said he had recently failed to get approval for a proposal to redevelop a joint venture in Velachery despite repeated attempts. “The government is losing crores of rupees in revenue. Registration alone used to generate nearly ₹ 10,000 crore annually from sub-registrar offices in Velachery and Adyar, while Greater Chennai Corporation (GCC) and CMDA are also losing revenue from property tax and building permits,” he said. However, wetland ecologists warn that the debate cannot be limited to property rights alone. The ecological health of Pallikaranai depends not only on the swamp but also on the surrounding landscape. The term “zone of influence” itself means that activities outside the wetland can affect what happens inside it, said Jayashree Vencatesan, managing trustee of the Care Earth Trust. “Imagine you have a clean house surrounded by trash. Eventually, dust and debris will get into the house. Likewise, if the hydrology around the marsh changes, 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 just as an isolated protected area. The zone of influence must therefore be defined very carefully, otherwise decades of conservation work could be undone.”
‘Demarcation in progress’
According to the CMDA, the one kilometer impact zone is unjustified and has stopped real estate development across the main IT corridors of Old Mahabalipuram Road and East Coast Road. TNSWA argues that the one kilometer influence zone should not be considered a permanent regulatory boundary. Srinivas R. Reddy, Principal Chief Conservator of Forests (Head of Forest Force) and Member-Secretary of TNSWA said that the current one kilometer zone was adopted as a temporary precautionary measure based on the best available information at the time and should not be considered a scientifically determined buffer. “The one kilometer zone was proposed based on the information available at the time. It is a temporary precautionary demarcation and not a final scientifically established boundary,” he said.
Mr. Reddy explained that 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 (Protection and Management) Rules 2017, a process that requires detailed scientific studies before regulatory boundaries are finalised. “As part of this exercise, we will carry out scientific due diligence to identify the exact extent of the wetland and its ecological characteristics. Only then will the zone of influence be delineated,” he said.
The district administration verifies 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 validation of the wetland boundary and recommend a final impact zone. TNSWA says this process is to ensure that the final notification is based on scientific evidence rather than general assumptions. For residents, however, uncertainty has persisted for almost a year. Many say they are unsure whether they will eventually be allowed to build, redevelop, mortgage or even sell properties that were bought legally and, in many cases, developed with approval granted by public authorities decades ago.