La Mesa Dam and Reservoir

Aerial view of Novaliches Reservoir, 1940

The La Mesa Dam was constructed in 1929 during the United States administration of the Philippines. Sometime between 1920 and 1926, the Metropolitan Water District (a predecessor agency of the Metropolitan Waterworks and Sewerage System) decided to build a replacement for the old Wawa Dam in Montalban, Rizal. The Wawa Dam which serves Manila and surrounding locales had to be replaced due to the growing population of the Manila area.[1]

The La Mesa was built in Novaliches, which was then still part of the municipality of Caloocan due to the sloping topography of the watershed area from Bulacan. The La Mesa dam later became part of a larger dam system with the opening of the Ipo Dam in Norzagaray, Bulacan in 1936, the Angat Dam in the same locale in 1967. The three dams formed part of the Angat-Ipo-La Mesa water system.[1]

The La Mesa Dam was raised in 1959 to increase the reservoir's maximum capacity to its current level.[2]

The La Mesa Dam is an earth dam with a height of 24 meters (79 ft). The elevation at its crest is 82.5 meters (271 ft) while the elevation at its overflow section is 80.15 meters (263.0 ft).[3]

The La Mesa Reservoir has a maximum capacity of about 50.5 million cubic meters (1,780 million cubic feet). Water from the reservoir spills into the Tullahan River which transports the water to Manila Bay.[1]

The La Mesa Watershed Reservation which hosts the dam and reservoir is jointly administered, supervised, and controlled by the Department of Environment and Natural Resources of the Philippine national government and the is under the joint administration, supervision and control of the (DENR) and the Metropolitan Waterworks and Sewerage System (MWSS).[1]

Metro Manila and its surrounding areas are divided into two water concessionaires: Maynilad Water (red) and Manila Water (blue).

The La Mesa Dam is part of the Angat-Ipo-La Mesa water system which supplies water to the population of Metro Manila and surrounding provinces.[1]

The water collected in the reservoir is treated at the La Mesa and Balara Treatment Plants. The La Mesa facility has a design capacity of 2,400 million litters per day (mld) while the Balara facility has a capacity of 1,600 mld. The La Mesa treatment facility serves the western half of Metro Manila while the Balara facility serves the eastern portion of the metropolis.[4]

Whenever the water level of the dam drops below 69 meters (226 ft) or the critical mark, the MWSS, Maynilad, and Manila Water begin to regulate the water supply they dispense to their patrons.[1]

• List of lakes in the Philippines

• Angat-Ipo-La Mesa System from Manila Water Company
• La Mesa Watershed and Eco-Park