The National Irrigation Administration said Sunday that it followed Magat Dam discharge protocols and issued proper flood warnings to residents of Cagayan and Isabela two days before typhoon "Ulysses" made landfall in the country.
NIA, which supervises the operations of the Magat River Integrated Irrigation System, said water releases from Magat Dam were conducted on Nov. 9 "to maintain a safe water level" in preparation for the typhoon's rains.
"It is necessary to release water from the reservoir for purposes of preventing the dam from reaching its critical level of 193 meters above sea level that may compromise its structural integrity and may result to a catastrophe to nearby municipalities and more impact on a widespread flooding in Region 2 (Cagayan Valley)," it said.
Magat Dam's protocols on dam discharge and flood warning operations were strictly observed, NIA said.
NIA said it closely coordinated with the Office of Civil Defense, Provincial Disaster Risk Reduction Management Council, Philippine Atmospheric, Geophysical, and Astronomical Services Administration, Regional Agricultural Fisheries Extension Network group, and other concerned local government offices before, during, and after water releases were conducted.
It also noted that information on the current situation of Magat Dam and its water releases were disseminated through television, radio, print, social media, emails, text message, and sirens.
"All stakeholders were kept posted and updated as to the actual scenario of the water volume that may be flowing into their place on an hourly basis through SMS (short messaging service)."
NIA-MARIIS said its officials warned residents living near low-lying areas, particularly those adjacent to and along Magat River and Cagayan River, to move to higher and safer places as early as Nov. 9.
Prior to Ulysses, five tropical cyclones had affected Isabela and Cagayan and had experienced continuous rains for almost two months.
"During this period, two gates opened or an equivalent of four meters were opened to reduce water containment at the Magat reservoir," NIA said, but "as water inflow from our Magat watersheds continually increases, additional gates must be gradually opened to maintain the safe level of the Magat reservoir."
The continuous rains upstream of Magat Dam contributed to high inflows, while rivers on the Cagayan River had also reached its maximum capacity, causing river overflows, not only to the Cagayan River but its adjacent areas, it said.