Water level in the Mullaperiyar dam rose to 130.7 ft on Friday against the allowed capacity of 136 ft even as rain continued in the catchment area.
The reservoir may attain the full allowed capacity in a week as there was, on an average, a rise of 1.5 ft a day, sources said.
Tamil Nadu was drawing water at the rate of 1,500 sq ft per second.
An official attached to the Tamil Nadu Public Works Department said the Vaiga dam in that State would be full with water drawn from the Mullaperiyar dam if there was a rise of 20 more ft.
It is for the first time since 2000 that the level reached the highest in July. It was 114 ft and 120 ft in 2012 and 2011 respectively.
On touching 136 ft, the water flows down to the Idukki reservoir which is also reaching the full reservoir level (FRL). A rise of 27 ft will take Idukki to FRL.
Staff Reporter writes from Palakkad: The Malampuzha dam, the largest irrigation reservoir in the State, is fast filling up with the southwest monsoon lashing the district for more than a month now. Usually the reservoir reaches Full Reservoir Level (FRL) of 115.60 metres during the Northeast monsoon only.
The water level in the reservoir rose to 111.25 metres on Friday as against 106.51 metres this day last year.
If the rain continues for a couple of days, the reservoir may reach its FRL during the southwest monsoon itself, officials of the Water Resources Department said here on Friday.
Meanwhile, District Collector P.M. Ali Asgar Pasha issued a warning to the people living on the banks of the Siruvani river as the Siruvani dam is reaching its FRL of 878.50 metres.
The water level touched 877 metres on Friday.
According to a PTI report, rainfall occurred in most parts of Kerala on Friday.
The off shore trough at mean sea level from south Gujarat coast to Lakshadweep area now extends from south Gujarat coast to north Kerala coast, say weather.
Forecast for the next 24 hours says rain would occur in most places in the State.