With the depleting level in Bhatsa, the total quantity of water available for supply from all the six lakes that supply Mumbai’s water put together has reduced to 3.3 lakh million litres as opposed to 6 lakh million litres available this time last year.

As on Wednesday, the Bhandup Water Complex recorded the water level in the Bhatsa dam at 111.95 metres as against 125.80 metres last year. Already, the city’s water supply at 3,420 million litres a day (mld) is much lower than the demand of 4,300 mld.

According to officials from the Brihanmumbai Municipal Corporation’s Hydraulic Engineering department, over the last four months, the state government, which controls the Bhatsa Dam, has released a large amount of water from the dam, despite warnings from the BMC about the falling water level. “The water had to be let out for carrying out regular grilling and grouting work on the dam’s body. We hope to finish the work by April end,” said Secretary (Water resources) V Gaikwad. It was only after the BMC pressed the panic button last week that the state finally stopped releasing water.

In its written correspondence to senior BMC officials, the civic Hydraulic Engineering department had advised that the BMC should impose a 10 per cent cut in the city until the monsoon in order to have adequate water reserves in case of an irregular monsoon season.

Overruling the warning, senior civic officials, who have so far been promising an additional 70 mld to 100 mld in 2008, took a decision on Tuesday to dig into existing reserves and continue supplying the regular quantum of water till June 15.

Officials, however, admit that this could lead to an acute water shortage in the eventuality of a poor monsoon. “We will be reviewing the situation every fortnight along with the Meteorological Department. If the rainfall is below normal, we will have to impose 10 per cent to 50 per cent water cut all over Mumbai, post-monsoon,’’ conceded civic Hydraulic Engineer MM Kamble.

For now, the BMC will tide over the crisis by permitting the water level in Bhatsa to dip well below the “lowest drawable” level of 100 metres. “We will be going up to 87 metres deep,” said Kamble.

Bhatsa is a prime source of water for the eastern suburbs and some parts of the city and western suburbs. When questioned about the situation, Municipal Commissioner Jairaj Phatak said: “This subject would require detailed discussion. I will reply at the weekly press conference.”