Sparse rainfall leaves Mumbai’s catchment reserves low still

Tansa Lake at Shahpur, Thane district. FILE PIC

While the drizzle brought cheer to Mumbaikars, the lakes supplying water to the city received fairly less rainfall and haven't contributed to any rise in lake levels. The city received 166 mm of rainfall up till now, which is way below the June average of 493 mm. The lakes in the city - Tulsi and Vehar - received moderate rain but the small lakes stocked less than 2 per cent of the total water stock for the city. Out of seven lakes that quench the city's thirst, five are located at the border of Thane and Nashik, while two are in the Sanjay Gandhi National Park.

As the overall lake levels hit 5 per cent, the BMC started fetching water from the reserved stock of Bhatsa and Upper Vaitarna lakes in the last two weeks. Therefore, the lake levels remained constant. The monsoon officially reached Mumbai on June 10 and the Santacruz observatory recorded 166 mm rainfall till 8 am on Thursday, but it is way below the normal. Similarly, the lakes also haven't received much rainfall.

Bhatsa, which supplies 50 per cent of the city's water, received 159 mm of rain, while Upper Vaitarna received 82 mm of rain by Thursday. However, since the water level is below the lowest drawable level (LDL) and the BMC is drawing from the reserved stock beneath the LDL, both lakes are currently showing zero levels. Meanwhile, Modak Sagar, Tansa, and Middle Vaitarna recorded 121 mm, 167 mm, and 131 mm of rainfall, respectively. Tulsi and Vehar recorded 221 mm and 212 mm of rainfall.

"Though there are few splashes received in the lake area, it doesn't contribute to the lake level. It takes heavy rainfall of a week to percolate water into the land and then into lakes. As the monsoon took a small break, we are expecting it to revive soon," said an official from the BMC. But in the last two years, the lakes did not receive even this much rainfall till June 20. As per the record, all five lakes outside the city received rainfall in the range from 7 mm to 97 mm in both years.

The city has been observing the late arrival of monsoon in the past few years and this is the third year in a row that the city faced water cuts in June, which marks the first official month of monsoon. Even last year, the water stock started improving in the first week of July. The BMC had imposed a 10 per cent water cut from June 5. Currently, the BMC uses 53,000 million litres of water from a reserved stock of 2.28 lakh million litres. Additionally, the other five lakes have 77,082 million litres of water that may last till July end.

Observatory recordings

Colaba 294 mm
Santacruz 166 mm
Average rainfall of June 493 mm

Lake wise rainfall received

Upper Vaitarana
82 mm

Modak Sagar
121 mm

Tansa
167 mm

Middle Vaitarana
131 mm

Bhatsa
159 mm

Vehar
212 mm

Tulsi
221 mm