BMC scraps plans to build a dam to augment Mumbai’s water supply, instead opts for a desalination plant

BMC Commissioner Iqbal Singh Chahal.

Almost two years after the Brihanmumbai Municipal Corporation (BMC) announced its intention to build a dam to augment Mumbai’s water supply, it has scrapped the plan.

In an era when building dams is the norm, the cancellation of the plan came as a pleasant surprise. What was even more heartening was the reason given by the BMC. Iqbal Singh Chahal, the BMC chief, said the decision was based on learnings from the last two big cyclones that Mumbai has faced since 2020. The cyclones, rare on the west coast, were attributed to climate change. Taking note of this, Chahal said that one of the reasons for not opting for a dam was that it would have meant cutting down 4.5 lakh trees which, in turn, would have had an obvious detrimental impact on the climate.

Instead, the BMC has signed a memorandum of understanding (MOU) with the Israeli firm IDE to set up a desalination plant in the northern suburb of Manori. The plant will convert 1,800 million litres of sea water into potable water on a daily basis.  Chahal said that the pre-feasibility studies have been completed and tenders are being drawn up. The project is expected to be commissioned by 2024, after which work will begin on Phase II, with an additional capacity of 1,800 million litres a day.

To further augment the water supply for Mumbai’s population of approximately 20 million, Chahal said the BMC will be constructing six sewage treatment plants that will convert 2,400 million litres of sewage every day into potable water. The cost of these will be about Rs.20,000 crore. Currently, Mumbai consumes about 3,800 million litres a day. Projections show that by 2041, that will rise to almost 6,000 million litres.

The Gargai dam was to have been constructed in Palghar district to the north of Mumbai. The BMC’s change of plans means that the region will be spared the usual environmental damages that usually follow big infrastructure projects. About 840 hectares of land would have been submerged. Of this, 670 hectares is forest land while the rest is private and panchayat land. The dam would have displaced 185 families from the six villages of Ogada, Khodade, Tilmala, Pachghar, Fanasgaon and Aamle. Ogada and Khodade would have been completely submerged and the other four would have been partially submerged.

The dam would have been built at the cost of Rs. 3,105 crore and augmented the city’s water supply by just 440 million litres a day, far less than what the desalination plant plan offers. The BMC had realised the Gargai dam would be inadequate and had also planned another dam, Pinjal, as well as a river linking project called the Damanganga-Pinjal. All these projects had been hanging fire for more than 10 years. The human and environmental costs would have been extensive if the BMC had not scrapped them.