Government hydrologists warned of widespread flooding in Isabela and Cagayan after all seven spillway gates of Magat Dam in Isabela were opened Thursday afternoon to allow the release of more water from its reservoir due continuous increase in the dam's water level.
Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) hydrologist Jason Bausa said two additional gates were opened Thursday afternoon, bringing to seven the total number of gates releasing water from Magat Dam.
As of 7 p.m., the level of Magat Dam rose to 192.88 meters, which is already near its spilling level of 193 meters.
Bausa said Magat Dam's current inflow was measured at 6,908 cubic meters per second, while the total current discharge is 6,244 cubic meters per second.
“Masyado na itong malaki 'yung pinapakawalan ng Magat Dam para sa capacity ng Magat River pati na rin ng Cagayan River. (Magat Dam is releasing too much water for the capacity of the Magat River, as well as the Cagayan River),” hydrologist Richard Orendain said.
Magat River is a tributary of the Cagayan River.
“Ang Cagayan river 'di na kaya i-accommodate ang ganung kalaking volume ng tubig from Magat. Magkakaroon po tayo ng malawakang pagbaha sa Isabela at Cagayan lalong-lalo na sa malapit sa Magat River at Cagayan River. (Cagayan River can no longer accommodate such a large volume of water from Magat River. We will have widespread flooding in Isabela and Cagayan, especially near the Magat River and Cagayan River)," he said.
The watershed area of Magat Dam had already received substantial rains from recent weather events, including Typhoon “Ulysses.”
Areas that are likely to be affected by Magat Dam's release of water are the municipalities of Ramon, San Mateo, Aurora, Cabatuan, Luna, Reina Mercedes, Burgos, Naguilian, and Gamu, all in Isabela province.
PAGASA also issued a flood advisory for the following areas:
1. Upper main Cagayan River and its tributaries – Ganano River and Magat River
2. Middle main Cagayan River and its tributaries – Siffu-Mallig River and Pinacanauan Rivers of Ilagan, Tumauini and San Pablo
3. Lower main Cagayan River and its tributaries – Pinacanauan de Tuguegarao, Chico River, Pared River, and Dummun River
The weather bureau warned people living near low-lying areas, particularly those adjacent to and along these rivers to stay vigilant against possible landslides and flash floods.
Local Disaster Risk Reduction and Management Councils concerned were also advised to take appropriate actions.