November 19, 2020

Napocor issues updates on its five Luzon Dams

State-owned National Power Corporation (Napocor) issues updates on the statuses of the five large dams in Luzon it oversees and manages. These are Angat Dam in Bulacan, Ambuklao and Binga Dams in Benguet, San Roque Dam in Pangasinan and Caliraya Dam in Laguna.

Napocor said that Angat Dam’s elevation as of 8AM today is 212.40 meters above sea level (masl). Its spillway gates closed and stopped its water release on November 15 at 5:10pm with elevation 213.08 masl.

On November 12 at 1pm, Gate 2 was opened at 0.5 meter with spill discharge of 64 cubic meters per second (cms). Releasing water through the spillway gates is imperative to protect the integrity of the dam. Napocor said it did not release water prior the typhoon because the level was only at 206 masl.

As part of its protocol, all concerned LGUs were notified four hours before the spilling operations: Norzagaray, Angat, Bustos, San Rafael, Baliuag, Plaridel, Pulilan, Calumpit, Paombong and Hagonoy.

“From the first water release, we gradually increased gate openings because the water level continues to rise as water flows from the mountains start to fill the dam’s reservoir, reaching 214 masl. Though the maximum gate opening was only 2.0 meters, with an equivalent spill discharge of 278 cms.,” Napocor President and CEO Pio J. Benavidez said.

Further, while Napocor sympathizes with the towns extremely submerged in floodwater and mud such as Marikina, and portions of Rizal, the corporation clarifies that these areas are not part of the Angat River basin.

For the Ambuklao and Binga Dams in Benguet, Binga Dam has been releasing waters since November 7, 2020 with 0.3 meter opening at Gate 3 while Ambuklao Dam opened its Gate 3 at 0.3 meters opening on November 9, 2020.

As of 8am today, Binga Dam still has two gates open (Gate 2 and Gate 3 at 0.3 meter opening for each) while Ambuklao Dam has one gate open (Gate 4 at 0.5 meters).

All the water discharges from these two (2) dams are contained by the downstream reservoir of San Roque which is still below its spilling level of 280 masl. Elevation at 8am today is at 270.62 masl.

Meanwhile, the Caliraya Dam in Laguna did not conduct water spilling operations though a Notice of Preparatory Phase of Dam Discharge Warning Operation as a precaution was issued informing the public that the reservoir water level has reached to 287.72 masl at 2am of November 12, 2020. It can be recalled that the notice asked the people to be on alert in the event of spilling operations.

The Caliraya Dam, in fact, has never released water from its spillway gates ever since as this is a pump-storage facility. This means that water is pumped from Laguna de Bay to the Caliraya Reservoir, then the water is utilized for power generation flowing through the turbines going back to Laguna de Bay.

“We are assuring the public that Napocor practices prudence in our dam operations and decisions, always considering the safety of the communities downstream and preserving the dams safe water level, a great source used for domestic water supply, irrigation, and power,” said Benavidez. END