The water level at Angat Dam in Bulacan could fall to its critical level in the coming days as rainfall in its watershed remains significantly below forecast, according to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).

During a climate forum on Wednesday, June 24, PAGASA-Hydrometeorological Division weather specialist Jofren Habaluyas said the reservoir’s water level was at 163.5 meters as of 6 a.m., only 3.5 meters above the critical level of 160 meters.

Angat Dam, located in Norzagaray, Bulacan, supplies most of Metro Manila’s domestic water requirements and has a normal high water level of 210 meters.

Habaluyas noted that the reservoir’s water level is currently declining at a rate of nearly 0.5 meter per day.

“So we're expecting na umabot na ito sa critical level na 160 kung saan possible water shortages will occur kasi most of our supply of domestic water still comes from Angat (We are expecting it to reach the critical level of 160 meters, where possible water shortages may occur because most of our domestic water supply still comes from Angat),” he added.

Habaluyas said Angat Dam’s water level previously fell below 160 meters in 2010 and 2019, both of which were El Niño years.

PAGASA announced on June 9 that El Niño conditions are already present in the tropical Pacific.

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He attributed the continued decline to lower-than-expected rainfall in the Angat watershed.

“This is different from our projected scenario last month na kung saan inaasahan sana natin na 280 millimeters na rainfall for June. ‘Yung observed reservoir rainfall only averaged 127 millimeters from June 1 to June 22. So parang hindi pa umabot sa 50 percent nung forecast rainfall value. Kaya naman po patuloy ‘yung pagbaba ng Angat (This is different from our projected scenario last month when we expected 280 millimeters of rainfall for June. The observed reservoir rainfall only averaged 127 millimeters from June 1 to June 22, which did not even reach 50 percent of the forecast rainfall value. That is why Angat continues to decline),” he said.

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Despite the current situation, PAGASA still expects the reservoir to begin recovering by the second or third week of July as rainfall increases during the southwest monsoon or “habagat” season.

“Ganoon pa man, ‘yung recovery period is still by the second or third week of July and we are expecting Angat's water level to continuously rise until the end of the year (Nevertheless, the recovery period is still expected by the second or third week of July, and we are expecting Angat’s water level to continuously rise until the end of the year),” Habaluyas said.

Based on PAGASA’s projections, assuming a dam allocation of 48 cubic meters per second and forecast basin rainfall of 493.2 millimeters, Angat Dam’s water level could reach 176.33 meters by July 31.

While this would be higher than its current elevation, Habaluyas noted that it would still remain below the reservoir’s rule curve and well below its normal high water level.

“So mas mataas ito sa current elevation niya na 163.99. Below rule curve elevation pa rin na 3.67 meters and 33 meters away from the normal high water level,” he said. (“This is higher than its current elevation of 163.99 meters. However, it remains 3.67 meters below the rule curve elevation and 33 meters short of the normal high water level.”)

However, he warned that the effects of El Niño may continue to be felt into early 2027.

“So still, ‘yung caution pa rin natin kahit mag-recover yung Angat is for the first quarter of the following year kasi magli-linger ‘yung effects ng El Niño leading to the dry season of 2027. Kaya hopefully, at least umabot man lang sa normal high water level Angat by December 31 (Our caution remains even if Angat recovers because the effects of El Niño will linger into the dry season of 2027. Hopefully, Angat will at least reach its normal high water level by Dec. 31),” he said.