Chennai to Desilt Poondi and Chembarambakkam Reservoirs After Seven Years to Restore Water Storage Capacity

The Water Resources Department (WRD) is set to begin desilting work at the Poondi and Chembarambakkam reservoirs after nearly seven years. Officials estimate that silt accumulation has reduced the effective storage capacity of three of Chennai`s major drinking water reservoirs by 15% to 20%.

The initiative follows Chief Minister C. Joseph Vijay`s directive to take advantage of the current low water levels in the reservoirs and expedite desilting before the northeast monsoon.

According to senior WRD officials, around 400 million cubic feet (mcft) of accumulated silt will be removed from the Poondi and Chembarambakkam reservoirs to restore part of their original storage capacity.

The proposal is currently in its preliminary stage, and the project is expected to commence shortly under a revenue-and-expenditure model.

Low Water Levels Provide an Opportunity

Officials said the receding water levels have created a limited window to carry out excavation work.

At present, Poondi Reservoir holds less than one-third of its total capacity of 3,231 mcft, while Chembarambakkam Reservoir is at around two-thirds of its full capacity of 3,645 mcft. These conditions make it feasible to deploy heavy excavation equipment for desilting operations.

Before work begins, the State government must clear a few policy-related decisions. Once approvals are received, the field work is expected to take about one month.

Officials also noted that if the northeast monsoon is delayed due to possible El Niño conditions, the department will have additional time to complete the desilting work.

First Large-Scale Desilting Since 2018

The WRD last undertook reservoir desilting under a 2018 Government Order, covering the Poondi, Chembarambakkam, Red Hills, and Cholavaram reservoirs.

Desilting work at Chembarambakkam began in 2019 but remained incomplete, while the Poondi project was halted due to litigation. Desilting is currently under way at Cholavaram, and the Institute of Water Studies has completed the feasibility study for the Poondi project.

Reservoir Storage Falls to 44.31%

The proposed desilting exercise comes as the combined storage across Chennai`s six drinking water reservoirs has declined to 5,858.25 mcft, representing 44.31% of their total storage capacity of 13,222 mcft.

Officials believe the current low water levels provide an ideal opportunity to restore storage capacity before the arrival of the northeast monsoon.

Experts Recommend Long-Term Maintenance

A retired WRD official said that desilting drinking water reservoirs can only be carried out when water levels recede and should be supported by a long-term maintenance strategy.

The official also stressed the importance of preparing a clear plan for the utilisation and disposal ofof the excavated silt to ensure the long-term sustainability of reservoir management.

If completed successfully, the project is expected to improve Chennai`s drinking water storage capacity, enhance reservoir efficiency, and strengthen the city`s long-term water security.