THROUGH its subsidiary WawaJVCo, Manila Water is reinforcing public safety and disaster resiliency protocols during the active rainy season, focusing on communities situated downstream of Upper Wawa Dam in Montalban, Rizal.
While constructed primarily as a water supply source, the modern infrastructure serves a critical secondary function as a flood mitigation mechanism.
Featuring a 262-square-kilometer watershed and a 120-million-cubic-meter reservoir equipped with a stepped chute and stilling basin, the facility actively regulates downstream flows, reduces soil erosion, and lowers severe flood risks for Rizal province and Marikina City by capturing excess rainfall.
During periods of intensified southwest monsoon (habagat) activity and typhoons, the reservoir frequently reaches its Full Supply Level (FSL) of 135 meters above sea level (masl).
This leads to controlled overspill conditions—a normal operational process where water flows naturally through the dam structure once designated operating capacity is achieved.
Recent heavy rain events that triggered overspills highlighted the necessity for continuous monitoring and rapid information sharing between water authorities and local government units (LGUs).
Under established operational protocols, WawaJVCo monitors reservoir levels alongside conditions across the broader watershed, including key tributaries and interconnected waterways of the Marikina River system such as the Puray, Manga, and Nangka Rivers, and Ampid and Burgos Creeks.
When water elevations reach critical thresholds—such as 136 masl, which directly impacts downstream monitoring stations—WawaJVCo issues hourly advisories to local disaster risk reduction and management offices to facilitate timely emergency responses.
“Events like these underscore the value of having robust monitoring systems and clear communication channels in place. The ability to continuously monitor conditions and promptly share information helps support preparedness efforts among local government units and communities,” said Joe Costales, General Manager of WawaJVCo.
As the rainy season continues, Manila Water urges downstream residents to remain vigilant and follow official advisories issued by local government authorities.
The company reaffirmed its commitment to maintaining safe, responsible dam operations while coordinating closely with government agencies to bolster climate resilience and protect public safety.
