Mumbai's Powai Lake clean-up spurs tree alarm

Mumbai: Environmentalists and residents have lauded civic authorities for accelerating work to divert sewage from entering Powai Lake but raised serious concerns over the Brihanmumbai Municipal Corporation’s (BMC) plan to transplant 112 trees for the construction of a sewage treatment plant (STP).

The clean-up drive — aimed at halting the daily discharge of 18 million litres of untreated sewage from 18 inlets into the 210-hectare wetland — has gathered pace. However, the proposed transplantation of trees from the STP site near Suvarna Mandir in Powai has sparked fresh debate over the ecological cost of restoration.

At a recent site briefing attended by local MLA Dilip Bhausaheb Lande and members of the Powai Advanced Local Management (ALM) committee, BMC officials said 1.1 km of sewage pipeline has been laid along the lake’s banks, against a total planned stretch of 2.4 km. Thirteen labour gangs are working section-wise on the project, which is targeted for completion by May 2026.

The diversion plan will intercept multiple sewage inlets — including seven to eight from the IIT periphery. IIT authorities have informed the BMC that they will independently address and manage the sewer inlets originating within their campus limits to prevent discharge into the lake.

An 8 MLD STP is proposed at Suvarna Mandir, with construction expected to take two years. Until then, diverted sewage will be sent to the Bhandup Pumping Station, which is being upgraded to handle 225 MLD.

While appreciating the BMC’s response to sustained citizen pressure, Pamela Cheema, chairperson of the BMC-mandated ALM, urged the civic body to examine alternative alignments to minimise tree loss. “With AQI levels deteriorating, protecting mature trees is critical. Transplantation must be the last resort,” she said.

The STP site reportedly has 212 trees, of which 122 are proposed for transplantation.

Environment watchdog NatConnect Foundation echoed the concerns, cautioning that the survival rate of transplanted trees in Mumbai is often below 40%. The group noted that Mumbai’s per capita tree cover is roughly one tree for every four persons — far below even the reduced urban norm of three trees per person.

Activists also invoked the globally recognised 3-30-300 rule for urban greenery — three trees visible from every home, 30% neighbourhood canopy cover, and a park within 300 metres — arguing that Powai must strengthen, not weaken, its green buffers.

NatConnect director B N Kumar described the sewage diversion as a “major breakthrough after years of neglect,” pointing out that repeated mechanical weed removal failed because nutrient-rich sewage continued to fertilise invasive growth.

Powai Lake, once a key source of drinking water for Mumbai, had steadily degraded due to unchecked pollution, prompting citizen groups to launch a rejuvenation movement.

“Stopping sewage is the single most critical intervention. But ecological restoration cannot come at the cost of further tree loss,” Kumar said.

Listed as a major wetland by the Union environment ministry, Powai Lake — home to protected marsh crocodiles — has emerged as a test case for citizen-led environmental accountability.

As pipeline work advances, residents say the clean-up must balance engineering urgency with ecological prudence — ensuring that saving the lake does not mean sacrificing its trees.