Navi Mumbai holding ponds’ capacity shrinks nearly 80% raising monsoon flood risk

Navi Mumbai: An Indian Institute of Technology (IIT-Bombay) expert survey report submitted to the Navi Mumbai Municipal Corporation has flagged a serious reduction in the storage capacity of the city's 14 holding ponds, raising concerns about flooding during the monsoon, especially when heavy rainfall coincides with high tide. The retention ponds function as a protective shield for Navi Mumbai by temporarily storing excess rainwater during intense downpours.However, according to the IIT survey findings cited by the civic body, the ponds' original storage capacity has dropped by nearly 80% over the last few years due to silt accumulation. With significantly less space available to hold stormwater, runoff is more likely to spill into surrounding areas. Civic officials said the impact is already being observed.During episodes of heavy rainfall and high tide, water has been accumulating in some low-lying parts of the city. The situation has been further complicated by the growth of mangroves in and around sections of the retention pond area over the years, which residents and officials say has altered water movement and reduced effective holding capacity in certain pockets.Municipal commissioner Dr Kailas Shinde said that the corporation is preparing to act on the IIT-backed assessment. A permission process is currently underway with the High Court to allow desilting of all 14 holding ponds, said Shinde. The proposed desilting drive aims not only to restore lost capacity but to increase the ponds' holding capacity by around 20% compared to the earlier benchmark, added Shinde.In parallel, the civic body has initiated an approval process to replant mangroves at an alternative location, as part of an effort to balance environmental safeguards with flood management needs. Officials said the planned interventions are intended to improve stormwater storage during peak monsoon events and reduce the risk of waterlogging and flooding in vulnerable areas of Navi Mumbai.NatConnect Foundation's director B N Kumar said the mangrove spread and silt formation could not have occurred overnight. "This is nothing but the result of years of neglect by the civic authorities," he said, adding that the Maharashtra Coastal Zone Management Authority had previously deferred approvals for mangrove removal, seeking detailed reports from the civic body."We have followed the authority's proceedings. Clearances are generally granted once proper documentation is submitted," he said, citing several instances of expedited approvals, including clearance involving mangroves for the Versova-Bhayandar Coastal Road project. Activists said they would not have opposed removal of excessive mangroves inside the holding ponds, as these reservoirs are crucial for flood mitigation by retaining excess rainwater.