Heavy rain and gusty winds lashed Mumbai on Wednesday as the southwest monsoon intensified along the western coast, prompting the India Meteorological Department (IMD) to issue a yellow warning while pushing Tansa Lake to overflow and raising the city’s reservoir stock to nearly 62%.
Event Context
In the 24-hour period ending 8am on Wednesday, Mumbai recorded an average rainfall of 36.65mm in the city, 48.70mm in the eastern suburbs and 64.91mm in the western suburbs.
Among the reservoirs, Upper Vaitarna stood at a water level of 598.94 metres, recording a rise of 0.21 metres in the past 24 hours and storing 88,631 ML, or 39.04% of its live storage capacity. Modak Sagar rose by 0.62 metres to 161.57 metres, with 116,181 ML of water, taking it to 90.12% of capacity. Tansa reached 128.47 metres, up by 0.35 metres, with 142,122 ML of usable storage, or 97.96% of capacity, before overflowing later in the morning. Middle Vaitarna recorded the highest rise in water level among the reservoirs at 1.16 metres, reaching 268.42 metres and storing 102,585 ML, or 53.01% of capacity.
Bhatsa, Mumbai’s largest reservoir, witnessed the highest increase in water level over the past day, rising by 1.72 metres to 129.60 metres. It now holds 410,644 ML of water, accounting for 57.27% of its total live storage capacity. Vihar Lake remained at 100% capacity with 27,698 ML of water despite a marginal fall of 0.04 metres in water level, while Tulsi Lake continued to remain full at 100%, holding 8,046 ML, with its level rising by 0.01 metres.
The reservoir catchment areas continued to receive widespread rainfall. Upper Vaitarna recorded 224mm of rain during the last 24 hours, the highest among all catchments, taking its cumulative seasonal rainfall to 1,455mm. Bhatsa received 96 mm, while Middle Vaitarna received 71mm, Tulsi 71mm, Tansa 70mm, Modak Sagar 67mm, and Vihar 65mm. Cumulative seasonal rainfall has reached 2,568mm at Tulsi, 1,911mm at Vihar, 1,735mm at Tansa, 1,706mm at Modak Sagar, 1,511mm at Bhatsa, 1,455mm at Upper Vaitarna and 1,287mm at Middle Vaitarna. The Bhandup Complex recorded 52mm of rainfall during the last 24 hours, taking its cumulative seasonal rainfall to 2,006mm.
Match Outlook
The IMD has forecast a cloudy sky with moderate to heavy rainfall at a few places in Mumbai and its suburbs for the day. Occasional gusty winds reaching 50-60kmph are also likely. In its 7am nowcast, the IMD issued a yellow warning, forecasting light to moderate spells of rain at isolated places accompanied by gusty winds of 40-50kmph over the next three hours.
The city is expected to witness high tide at 5.57am (3.27 metres) and 5.30pm (3.32 metres) on Wednesday.
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Heavy rainfall over the past 24 hours also significantly improved Mumbai’s water reserves, with the combined stock in the seven reservoirs supplying drinking water to the city rising to 61.90% of their total live storage capacity. According to the Hydraulic Engineer’s Department, Bhandup Complex, the reservoirs collectively held 8,95,907 million litres (ML) of usable water at 6am on Wednesday, an increase of 4.15 percentage points from the previous day. The total live storage capacity of the seven reservoirs is 1,447,363 ML. During the corresponding period last year, the reservoirs were 85.32% full, while in 2024 they stood at 47.29%.
The rainfall also led to Tansa Lake beginning to overflow at 8.51am on Wednesday, prompting authorities to open Gates 1 and 9 of the dam to regulate excess inflow. Tansa, located in Shahapur taluka of Thane district, is one of Mumbai’s key drinking water sources. It is the third reservoir to overflow this monsoon after Vihar Lake, which overflowed on July 7 at 9pm, and Tulsi Lake, which overflowed later the same night at 11.43pm.
