Angat Dam needs at least 350 millimeters of one-time rainfall occurrence to reach its 180-meter minimum operating level, the State weather bureau said yesterday.
Since the past week, the water level at Angat Dam continues to decline and remains below its 160-meter critical level.
As of yesterday morning, Angat Dam’s water level was 158.75 meters, down by 40 centimeters from last Sunday’s 159.15 meters.
Philippine Atmospheric, Geophysical, and Astronomical Services Administration hydrologist Richard Orendain said Angat Dam needs at about 350 mm of one-time rainfall event to reach the water reservoir’s 180-meter minimum operating level.
It needs at least 1,160 mm of rainfall, equivalent to four to five tropical cyclones, to reach its 210-meter normal high water level, he added.
While tropical depression “Falcon” is not seen to move directly over the Angat watershed in Norzagaray, Bulacan, the southwest monsoon or “habagat” may still contribute to the gradual recovery of the water reservoir, PAGASA Weather Division chief Esperanza Cayanan said.
From Tuesday until Wednesday, monsoon rains may contribute about 150-mm rainfall over the Angat watershed.
“So far, our forecast shows that the rainfall over the watershed will not reach the 350-mm rainfall from monsoon rains alone, but there are still thunderstorms that may also help increase the Angat Dam’s water level,” Cayanan explained.
Citing PAGASA historical record, she said Angat Dam’s level usually normalizes towards the end of July to early August.
Two to three tropical cyclones usually affect the country in July, two to four in August, and two to four in September.
Once the Angat Dam reaches its 180-meter minimum operating level, the National Water Resources Board may increase the water allocated for Metro Manila’s domestic requirements.
The current water allocation of 36 cubic meters per second is split 60-40 to water concessionaires Maynilad and Manila Water, respectively.
The normal water allocation for the domestic requirements of consumers in Metro Manila and nearby provinces is 48 cms. (Ellalyn V. Ruiz)
