The Freeze Around Chennai’s Largest Wetland
The Tamil Nadu government’s curbs on construction around the Pallikaranai Marshland have sparked tension between developers and environmental regulators. Following National Green Tribunal (NGT) and Madras High Court interventions, all new building approvals within 1 km of the Ramsar-designated wetland are currently on hold.
The move, though vital for conservation, impacts over 13 revenue villages with thousands of housing units, IT parks, and infrastructure projects already underway.
Timeline of Key Events
| Date | Event |
|---|---|
| June 2023 | NGT initiates suo-motu case after debris road appears across the marshland. |
| Aug 2023 | District Collector finds encroachment and illegal construction within marsh limits. |
| Jan – Aug 2024 | CMDA admits approvals issued before full boundary mapping. |
| June 2025 | TN State Wetland Authority identifies 304 survey numbers within Ramsar/influence zone. |
| Sep 24 2025 | NGT directs freeze on all planning approvals until scientific delineation and Integrated Management Plan (IMP) are complete. |
| Oct 6 2025 | CMDA circular formally bans construction within Ramsar + 1 km buffer. |
| Oct 24 2025 | ₹2,000 crore housing scam alleged; specific survey numbers flagged. |
| Oct 31 2025 | Madras High Court halts Brigade Morgan Heights project (1,400 units) till Nov 12. |
Villages and Survey Numbers Impacted
The Wetland Authority’s June 2025 report lists 304 survey and sub-division numbers across seven core revenue villages within the Ramsar site and its influence zone:
- A report says there are “304 survey and subdivision numbers across seven revenue villages: Perumbakkam, Sholinganallur-I, Pallikaranai, Perungudi, Jalladianpet, Injambakkam, Okkiyam Thoraipakkam” falling within the boundary of the Pallikaranai Marshland/Ramsar site.
- The same report flags specific survey numbers for the case in Perumbakkam: “survey numbers 285 and 286 were recorded as patta ‘ryotwari wetlands’.”
- Some NGO allegations list survey numbers 453, 495/2C, 496, 497, 498 as being claimed to fall within the marsh/Ramsar boundary.
In addition, CMDA’s 2025 circular extends the restriction to nearby 15 revenue villages—including Puzhuthivakkam, Madipakkam, Kulathur, Arasankalani, Semmancheri, Karapakkam, Seevaram, and Velachery—categorised as the 1 km influence zone.
Developers’ Pushback
The Builders’ Association of India (BAI) argues that the blanket freeze will disrupt the livelihoods of nearly five lakh residents and stall affordable housing in approved layouts.
State Chairman K. Venkatesan told that the ambiguity in boundary demarcation is punishing ordinary buyers more than errant developers, urging the government to publish clear zone maps before extending bans.
Ecological and Legal Imperative
Environmentalists maintain that the freeze is non-negotiable. Pallikaranai—one of India’s 75 Ramsar sites—absorbs monsoon runoff from the southern suburbs and supports migratory birdlife. Unchecked construction in its floodplain has worsened Chennai’s flooding vulnerability.
Under the Wetlands (Conservation and Management) Rules 2017, final notification of Ramsar boundaries requires:
- Map publication and 60-day public consultation, then
- 240-day review period before Gazette notification.
Until that process ends, the marsh’s official boundary—and permissible building extent—remains unresolved.
Impact on Buyers and the Market
If your plot lies in the 1 km buffer or among the 304 flagged survey numbers, expect delayed or revoked approvals.
Even legally issued permits may be frozen pending boundary confirmation. For transparency, buyers should:
- Obtain the survey number and verify zoning through Verified.RealEstate’s Due Diligence Tool,
- Cross-check with CMDA’s latest wetland restriction map, on Verified.Realestate ,using geo insights map for a better understanding of the area.
- Avoid commitments until the final Wetland Authority notification is out.
Final survey-number list is being verified by the state, and the list is pending official notification.
Sources: TNSWA/DoSS report to NGT; CMDA Office Order no. 7/2025; NGO Arappor Iyakkam complaint