Mamallan Reservoir: Chennai’s Sixth Water Source & Coastal Milestone

Official Foundation. Tamil Nadu Chief Minister M.K. Stalin laid the foundation stone for the ₹342.60-crore project at Vada Nemmeli on the East Coast Road (ECR).
Implementing Agency. The project is being executed by the **Water Resources Department (WRD)** within the Kovalam sub-basin.
Geographic Scope. The reservoir will occupy the land parcel between **Thiruvidanthai and Kokilamedu**, strategically positioned between the ECR and Old Mahabalipuram Road (OMR).

Source

Naming Significance. The reservoir is named after **Narasimhavarman I**, the 7th-century Pallava emperor popularly known as “Mamallan” (the Great Wrestler), who founded the nearby town of Mamallapuram.
Water Wisdom. The Chief Minister highlighted that the Pallavas were pioneers in water management, creating nearly **39 massive irrigation tanks**—such as Uthiramerur and Thenneri—which continue to function over 1,300 years later.
Cultural Continuity. By naming the project after a Pallava ruler, the government signals a return to traditional “tank-based” security adapted for modern urban needs.

Massive Footprint. The reservoir will spread across **5,161.27 acres**, making it one of the largest modern water bodies in the region.
Total Capacity. It features a storage capacity of **1.65 tmcft** (thousand million cubic feet).
Annual Potential. With the ability to be filled twice a year using monsoon surplus, the annual storage capacity is estimated at **2.25 tmcft**.
Daily Supply. Once operational, the reservoir will have the potential to supply **170 million litres a day (MLD)** to the city’s grid.

Surplus Capture. The reservoir is designed to store surplus water from **69 upstream tanks** belonging to the Manamathy tank group.
Preventing Waste. Currently, this excess water drains into the sea; the new system will divert this flow into the coastal reservoir via a series of channels and sluice gates.
Silt Management. As part of the project, approximately **34 lakh cubic metres of silt** will be cleared from the 69 feeding tanks to restore their original holding capacity.

Earthen Embankment. To hold the freshwater, a massive **34-km-long earthen bund** (embankment) will be constructed along the perimeter.
Flood Control. The southern end will feature a **sluice gate** near the Kokilamedu estuary to facilitate the controlled release of extreme floodwaters during cyclones.
Inlet/Outlet Systems. The design includes dedicated sluice gates for water intake and rainwater discharge to manage the reservoir’s levels throughout the year.

Seawater Intrusion. By maintaining a large body of freshwater near the shore, the project will act as a hydraulic barrier, preventing **saltwater intrusion** into the coastal aquifers.
Groundwater Quality. The reservoir is expected to significantly recharge the groundwater table in neighboring localities like **Thiruporur, Thandalam, and Paiyanur**.
Salinity Barrier. This “coastal freshwater” model is a first for Tamil Nadu, intended to protect the delicate ecology of the ECR stretch from becoming saline.

Total Reach. The project is set to benefit approximately **13 lakh residents** living in the rapidly urbanizing southern corridor of Chennai.
Primary Zones. Key areas include **Sholinganallur, Medavakkam, Pallikaranai, and Siruseri** (home to major IT hubs).
Suburban Growth. It also addresses the long-standing water scarcity in **Thiruporur and Mamallapuram**, which have seen massive population growth but lacked reliable piped water.

Fisheries Support. A vital component involves restoring a **15-km-long stretch** of the Buckingham Canal between Thiruvidanthai and Mamallapuram.
Socio-Economic Impact. The restoration, covering **311 acres**, will improve the livelihood of fishermen who depend on brackish water fishing.
Fishing Rights. The Chief Minister confirmed that **fishing licenses** would be issued to local fishermen to ensure they benefit directly from the revitalized water body.

Cost Efficiency. Compared to desalination, which costs significantly more to process and transport, the Mamallan reservoir offers a **lower-cost freshwater alternative**.
Drought Buffer. By storing monsoon excess, the reservoir acts as a “buffer” during the dry summer months, reducing the city’s reliance on distant sources like Veeranam or Mettur.
Strategic Diversification. With this sixth reservoir, Chennai now has a **diversified portfolio** of sources: Poondi, Cholavaram, Red Hills, Chembarambakkam, Thervoy Kandigai, and now Mamallan.

Swastika Shiksha