The storage in the Siruvani reservoir reached the brim and began to overflow for the second time this year on Sunday.
Tamil Nadu Water Supply and Drainage Board Chief Engineer Mohanasundaram, Superintending Engineer Thirumurthy, Executive Engineers S. Sampath Kumar and V.T. Nagarajan reviewed the situation on Monday and said that fullest quantity of 101.4 mld would be given as withdrawal for drinking water supply needs.
With the North East monsoon expected to set in over the next few weeks, officials anticipated the reservoir to surplus again in October or November and pointed out that such a situation would help in taking care of the drinking water needs of the city and wayside habitations till the setting in of the next South West monsoon.
According to official sources, the water level touched the full reservoir level of 878.5 metres (50ft) on Sunday.
Officials said that overflowing for the second time in a year had not occurred for the past four years. Even before that, the second overflow would usually occur only after or during North East monsoon period i.e. in October or November (October to December is North East Monsoon period) and the first overflow would normally be during the South West monsoon period (June to September).
The Siruvani catchments witnessed a rainfall of 25mm on Saturday and 10mm on Sunday while the foot hills recorded 3mm on both days. The last overflow in Siruvani was August 1 this year and the overflow lasted till August 17. From August 17, the water level started receding owing to withdrawal and it went down by 30cm. The Siruvani had earlier surplused on September 1, 2011 besides during 2007, 2008 and 2009.
During the peak summer season, when the storage hit the dead storage level, the Tamil Nadu Water Supply and Drainage Board took permission from Kerala for pumping water to the intake well and supply to the city came down to the lowest ever of 27 mld.