La Mesa Dam at Critical Levels as Southwest Monsoon Batters Metro Manila
As the southwest monsoon continues to affect large regions of the Philippines, the La Mesa Watershed in Quezon City has recorded near-critical water levels, raising concerns regarding potential disruptions to water supply in Metro Manila.
On July 20, 2025, the water level at La Mesa Dam reached a critical mark of 79.50 meters, prompting preemptive evacuation measures. Residents in vulnerable barangays near the dam and along the Tullahan River—specifically Commonwealth, Nagkaisang Nayon, Sta. Monica, Novaliches Proper, Gulod, Capri, San Bartolome, Sta. Lucia, Bagbag, North Fairview, and Fairview were advised to evacuate immediately. Emergency response teams, including the Quezon City Disaster Risk Reduction and Management Office (QCDRRMO) and the Philippine Red Cross, were deployed to assist.
By 8:00 a.m. on Monday, July 21, 2025, the water level at La Mesa Dam had increased to 79.69 meters, only 0.46 meters below its spilling threshold of 80.15 meters. On the same day, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) issued a hydrological advisory, warning residents in low-lying areas adjacent to the Tullahan River as the dam approached its spilling point. Areas of concern included Fairview, Forest Hills Subdivision, Quirino Highway, Sta. Quiteria, and San Bartolome in Quezon City, as well as portions of Valenzuela City, notably North Expressway and La Huerta Subdivision, and sections of Malabon.
The situation escalated early on July 22, 2025, as the water level at La Mesa Dam reached 80.17 meters, signifying that it is now exceeding its normal high-water level (NHWL) of 80.15 meters. PAGASA’s most recent observation reflects a water level of 80.16 meters as of today.
This development occurs in the context of persistent heavy rainfall affecting numerous provinces. In addition to La Mesa Dam, three other major dams in Luzon, Ipo Dam, Ambuklao Dam, and Binga Dam, opened their gates on July 22, 2025, to release excess water. The Department of Environment and Natural Resources (DENR) has issued a warning regarding deforestation and watershed degradation, which intensify flooding risks and diminish the water storage capacity of critical reservoirs such as La Mesa.
Residents of Metro Manila are advised to prepare for scheduled interruptions in water service commencing July 24, as the Metropolitan Waterworks and Sewerage System (MWSS) implements emergency water rationing measures. Authorities are mobilizing rapid response teams to bolster watershed protection efforts and disseminate warnings to communities situated in landslide-prone areas, particularly in the Sierra Madre foothills. The government underscores the necessity for robust collaboration among local government units and environmental agencies to address the multifaceted challenges imposed by climate-driven extreme weather events and land degradation, which are expected to exacerbate both water insecurity and flood hazards.
