THE La Mesa Dam in Quezon City is close to spilling over, threatening massive flooding in parts of Metro Manila and outlying areas, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) warned Sunday.
Pagasa hydrologist Rosalie Pagulayan told The Manila Times that as of 6 a.m. on Sunday, the La Mesa reservoir’s level was 79.79 meters.
Pagulayan said the level is expected to rise further because of incessant southwest monsoon rains, which are being enhanced by storm “Falcon” (international name: “Khanun”).
Once the level hits 80.15 m, water will overflow, Pagulayan said.
Because La Mesa Dam has no flood control mechanism, the excess water could swell the Tullahan River and flood nearby communities.
Among the areas at risk are Barangay Fairview, Forest Hills Subdivision, Quirino Highway and Sta. Quiteria in Quezon City, and low-lying sections in the cities of Valenzuela and Malabon, Pagulayan said.
“The concerned local government units have already been warned so that they can properly advise, especially those residents living near river banks, to be on alert and possibly be ready to be evacuated in anticipation of possible flooding,” she said.
On the upside, Pagulayan said, the monsoon rains have raised the water level at Angat Dam in Norzagaray, Bulacan, the main source of water for Metro Manila and adjoining provinces.
The level at Angat was 193.84 m as of 6 a.m. on Sunday, but is not likely to reach its normal high water level of 210 meters.
“The rainwater brought by the two storms (Egay and Falcon) has helped our major dams increase their water levels, but it is still not enough, especially for Angat Dam to fully reach its [normal level],” Pagulayan said.
The Ipo Dam, also in Norzagaray, where the level is slightly above the normal 101 meters, has opened one gate to slowly release excess water.
Ambuklao and Binga dams, both in Benguet province, have also started to discharge excess water, Pagasa said.
Meanwhile, Falcon will continue to interact with the southwest monsoon and bring “significant amount of rains” to Metro Manila and other Luzon provinces, Pagasa said.
The provinces of Bataan and Zambales could have as much as 200 millimeters of rain on Monday.
Pangasinan, Occidental Mindoro, and the northern section of Palawan, including Calamian, Cuyo and Kalayaan Islands, will have from 50 to 100 mm of rainfall, Pagasa said.
Bataan and Zambales had more than 200 mm of rain on Sunday.
Falcon has strengthened as it moved north-northwestward over the Philippine Sea, Pagasa said.
It was tracked at 1,170 kilometers east of extreme Northern Luzon, with 110 kilometers per hour (kph) winds gusting to 135 kph.
Falcon will likely reach typhoon strength either Sunday night or early Monday morning and further intensify in the next three days, Pagasa said.
It could exit the Philippine Area of Responsibility Monday evening or early Tuesday morning.