With the Water Resources Department desilting the Chembarambakkam and Cholavaram lakes for over a month, the two reservoirs, which cater to Chennai’s drinking water needs, may gain additional capacity ahead of the northeast monsoon.
Though the project began in September 2019, it was not consistent due to reasons such as getting environmental clearance, weather conditions and the lockdown.
Spread over 2,552 hectares, the Chembarambakkam lake has been able to store 10-20% less than its original capacity of 3,645 million cubic feet (mcft) due to silt deposits. The waterbody currently has a storage of only 1,824 mcft.
Officials said nearly 56,160 cubic metres of silt have been removed from the lake so far. This will also help in reducing flooding in the neighbourhood, they added.
As the project has been devised on a revenue generation model, the contractor will pay for desilting and later sell the excavated earth. A revenue of nearly ₹1.13 crore has been generated so far.
The department has planned to remove 151.80 lakh cubic metres of silt from Chembarambakkam and the process has been estimated to generate a revenue of ₹150 crore. Once the project is completed, the lake will have an additional storage of 536 mcft.
Similarly, of the 38 lakh cubic metres of silt proposed to be cleared from the almost dry Cholavaram lake, nearly 97,428 cubic metres has been removed. Officials said these two lakes would have an additional storage capacity of a minimum of 50 mcft by October.
Legal hurdles
However, projects in the Poondi and Red Hills reservoirs have been stalled due to pending court cases and steady inflow.
The lake in Red Hills is brimming with water this season. If the desilting project is completed, the four lakes will have an additional storage capacity of about 1,900 mcft.
The department is hesitant to propose new projects based on the revenue model due to issues such as pending court cases, sources said.
