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With water levels in the seven lakes that supply drinking water to Mumbai dropping to 28.79 per cent as of Monday morning, the Brihanmumbai Municipal Corporation (BMC) has decided to take a call on implementing a water cut ranging from five to 10 per cent starting May 1 to ensure the existing water stock meets the city’s demands till August. The decision will be taken within this week, considering the India Meteorological Department`s (IMD) indication of below-normal rainfall this year due to the weakening of the southwest monsoon owing to the El Nino effect.

According to the BMC, the water stock in Mumbai’s lakes is replenished by August from the rainfall received since June. However, with the IMD indicating a weak monsoon this year, the present water stock will last until the end of July.

A senior civic official told mid-day, “If the lakes do not fill up, we will need to sustain the existing stock till August-end. If lakes aren’t filled to the brim this monsoon season, we will face a water shortage until the rainy season next year. So, a decision has to be taken regarding the judicious use of the existing stock.”

Mumbai’s water sources

Mumbai receives 3950 to 4100 million litres of water per day (MLD) from seven lakes — Tulsi, Vihar, Bhatsa, Tansa, Modak Sagar, Upper Vaitarna and Middle Vaitarna. While Tulsi and Vihar are located in Sanjay Gandhi National Park, the remaining five are located in the Thane, Nashik, and Palghar districts. The total water holding capacity of the lakes is 14,47,363 MLD.

Related developments

As a precautionary measure, the BMC has requested the state government’s urban development department to withdraw one lakh million litres of water from the Bhatsa and Upper Vaitarna. If the state releases the additional stock, this can also help sustain the supply till August 31.

In preparation for El Nino, Maharashtra Chief Minister Devendra Fadnavis chaired a high-level review meeting in April to address the potential impact of a strong El Nino expected to emerge between June and August, including measures for water management across the state.