MANILA, Philippines - Despite frequent rains, water levels at dams in Luzon continue to be way below comfortable levels and could affect power supply in the region, the National Power Corp. (Napocor) said.

Napocor said it would take two typhoons equivalent to the strength of last year's destructive 'Ondoy'to bring back  to normal the water levels at Angat dam in Bulacan, and at the San Roque Dam in Pangasinan.

Angat dam supplies most of Metro Manila's water requirements, while San Roque provides irrigation and water supply for households in Pangasinan and other provinces in northwest Luzon.

Water levels are also still at critical levels in Ambuklao dam in Benguet, the biggest rock filled dam in Asia,
and at the Pantabangan dam in Nueva Ecija.

The abnormal water levels in these dams have serious implications for power supply and electricity prices in Luzon.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said that while the rainy season is starting,  water levels in Luzon's dams will only begin to normalize in September.

This means that power supply will continue to come from power plants running on more expensive energy sources, at least until the end of the third quarter.

Power plants operating on diesel or bunker fuel will have consumers paying at least P18 per kilowatthour.

In contrast electricity charges for most hydropower plants average just P2 per kilowatt hour.

Already, consumers are bracing for possible rotating brownouts.

On Monday night, several areas in Metro Manila experienced power outages as one substation in Sucat,
Paranque of the National Grid Corp. of the Philippines broke down.

The power grid has been and out of red alert status in recent months, as several hydropower plants remain offline.

The brownout caused traffic snarls, and stranded Metro Rail Transit passengers from the station in Taft Avenue up  to Shaw Boulevard in Mandaluyong. - based on a report of Alvin Elchico, ABS-CBN News