
Tulsi lake one of the seven catchment area lakes supplying water to Mumbai overflowed on Monday around 7:30 am.
Located within densely forested Sanjay Gandhi National Park, the freshwater lake is one of the second largest lakes in Mumbai and supplies part of the city's potable water.
The plan to create the lake was conceived in 1872 and construction completed in 1897. It was designed as a backup for the Vihar Lake to supply potable drinking water to the city of Mumbai.
According to Skymet Weather, extremely heavy Monsoon rains continued to lash Mumbai as the city recorded 3-digit rainfall for the second consecutive day on Sunday. In the past 24 hours from 8:30 am on Sunday, Colaba Observatory recorded 171 mm of rains, whereas Santa Cruz Observatory had witnessed 122 mm.
The heavy downpour caused waterlogging at several places and submerged rail tracks on some routes. 
There were delays in suburban trains, and many bus routes had to be diverted.
The rains also affected the Central Railway line as several train services have been temporarily shut down or delayed. 
School and Colleges have also been advised to remain shut.
Meteorological Department has predicted heavy to very heavy rainfall to continue further in parts of Mumbai, Thane, and Palghar from Sunday to Wednesday.