NIA reaffirms that recent flooding in Cagayan Valley is not wholly attributed to Magat Dam

January 6, 2021, 2:17 PM


NIA Central Office – The National Irrigation Administration (NIA) reaffirms that the recent flooding in Cagayan Valley is not wholly attributed to Magat Dam located in the Municipality of Ramon, Isabela.

During the onslaught of Typhoon Ulysses (Vamco) in Luzon on November 11-12, 2020, Magat Dam was pinpointed as the culprit in the widespread flooding within the Cagayan Valley Region, especially, in Central Isabela and in the entire stretch of lower Cagayan River System down to Aparri, Cagayan. However, based on the Flood Bulletin No. 3 Cagayan River Basin of the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA) Northern Luzon Regional Services Division, these areas were identified as low-lying and flood prone areas in the Region.

Cagayan River Basin is subdivided into three parts: Upper Cagayan River Basin (Ganano and Magat), Middle Cagayan River Basin (Siffu-Mallig, Pinacanauan Rivers of Ilagan, Tumaini, and San Pablo), and Lower Cagayan River Basin (Pinacanauan de Tuguegarao, Chico Pared, and Dummun).

Magat River Basin is only one of the 20 river systems within the Cagayan River Basin. Studies showed that Magat Dam contributes only 15% of the river basin’s total water storage capacity and 21% if the considered control point will be in Buntun Bridge, Tuguegarao City.

According to the Dam Protocols, PAGASA issues the Notice for Flood Precaution Period of the Dam Discharge Warning Operation for the Magat River Basin. If due to its data analysis and weather projection, heavy amount of rainfall may be expected within the next 24 hours due to large scale weather system. It is only upon the receipt of this Notice that the NIA-MARIIS Dam and Reservoir Division Flood Forecasting Warning System Dam Operation (FFWSDO) will activate its extensive early warning operation. This is a public warning system installed downstream of Magat Dam along Magat River, informing those in the low-lying areas regarding the opening of Magat Dam gate/s. Communication with stakeholders through various media is also sent for information dissemination and appropriate action. It is to be made clear that the handling of natural occurrences, such as this, is not the sole domain of NIA but a concerted effort of the Local Government Units (LGUs), Office of the Civil Defense (OCD), Provincial Risk Reduction and Management Council (PDRRMCs), all forms of media, the farmers, and other stakeholders in the affected communities.

The gradual opening of dam gates aims to lessen/drawdown reservoir elevation and to contain the water inflows expected in the forecasted heavy rainfall. However, Magat Reservoir drawdown should still be in accordance with its Rule Operational Curve. It cannot be done impulsively. Any adjustment or revision of the rule curve entails a study and coordination with various stakeholders, including PAGASA and Department of Agriculture (DA).

In this regard, the recent flooding in some parts of Cagayan Province cannot be wholly attributed to Magat Dam because that is an effect of the Frontal System and Amihan enhanced by Tropical Depression Vicky. The inflow and outflow experienced on December 19, 2020 is lesser by a half of the inflow and outflow of Typhoon Ulysses. Yet, even without spillage from the Magat Dam, flooding was already experienced in portions of Cagayan, which affected 219 farmers comprising 213 hectares of agricultural land in Cagayan Province, while MARIIS recorded 2,670 hectares of affected area (2,231 farmers).

With all data provided by the Agency, NIA Top Management Officials, headed by Administrator Ricardo R. Visaya, stand firm that the recent flooding in the Province of Cagayan and some portions of Isabela was caused by natural calamities which are beyond human control, contrary to the press release of Samahang Industriya ng Agrikultura dated December 21, 2020 accusing NIA of failing twice in dam water release. The Agency reaffirms that the opening of Magat Dam gates was in accordance with the existing guidelines.

As review of the protocol is on process, its finalization and subsequent implementation requires consensus of different Agencies. Magat Dam gates cannot and will not be opened and closed at the whim of NIA because life and property may be at a greater risk of danger.

**For questions and/or clarifications, you may contact:

Acting Department Manager
NIA Public Affairs and Information Staff
Landline: (02) 8921-3741