Angat Dam needs around 400 millimeters of rain over its watershed in Bulacan to reach the level needed for normal operations for domestic water supply, irrigation, and power generation, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said.

In a press conference on Thursday, July 23, PAGASA Hydrometeorology Division chief Engr. Socrates Paat Jr. said the amount is comparable to the more than 400 millimeters of rain dumped by Typhoon Ondoy in a single day.

“So, ganung ulan yung kailangan natin pero huwag naman sanang dumating yung ganung delubyo (That is the amount of rain we need, but hopefully, we will not experience such a disaster),” he said.

The 400 millimeters of rainfall would bring Angat Dam to its rule curve elevation, or the level needed for the dam to operate normally for domestic water supply, irrigation, and power generation.

However, Angat Dam would need around 1,200 millimeters of rainfall to reach its normal high water level of 210 meters.

Tropical Cyclone Kiyapo is expected to cause the water level of Angat Dam to rise in the coming days, although the increase will not be enough to address the reservoir's long-term deficit.

“In the long run talaga, for the case of Angat, tuloy-tuloy pa rin in the coming days na bababa siya pero may konting pag-angat in the coming days due to the impact nga nitong TC Kiyapo (In the long run, in the case of Angat, its water level will continue to decline in the coming days, although there may be a slight rise due to the impact of Tropical Cyclone Kiyapo),” Paat said.

PAGASA hydrologist Jofren Habaluyas said the forecast 100 millimeters of rainfall could raise Angat Dam's water level by an estimated five to seven meters.

“Kasulukuyan, na-experience po natin yung pinakamababang level pa rin sa Angat. So etong system naman is makakatulong naman sa pag-angat ng level ng Angat (Currently, we are experiencing the lowest level at Angat. This system will help raise Angat's water level),” he added.

Habaluyas said Kiyapo could also benefit other reservoirs, noting that around 100 millimeters of rainfall could potentially raise the water level of Magat Dam by eight to 10 meters.

PAGASA Deputy Administrator for Operations and Services Roy Badilla said Angat Dam's water level fell to 151.45 meters as of 8 a.m. Thursday, July 23, the lowest level recorded so far.

“We are not discounting na pwede pa itong bumaba dahil sa ngayon, wala pa rin tayong natatanggap na ulan doon sa Angat reservoir or sa catchment ng Angat (We are not discounting the possibility that it could still drop because, as of now, we have not received rainfall over the Angat reservoir or its catchment),” he said.

Paat said the expected El Niño could further worsen the country's water supply situation as rainfall may remain insufficient to replenish dams.

“We expect talaga na mayroon pa rin talagang kakulangan sa ulan na mag-su-supplement ng kailangang water level ng ating mga dams (We really expect there will still be a lack of rainfall needed to supplement the water levels of our dams),” he said.

Badilla said El Niño is expected to peak in the last quarter of the year and the first quarter of next year.

He urged the public to conserve water and reduce water-intensive activities as the country prepares for the expected dry conditions.

“Sana tumulong po yung mga tao, magtipid na tayo sa paggamit ng tubig (Hopefully, people will help by conserving water),” he said.

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