sentences:  It is part of the Angat-Ipo-La Mesa water system, which supplies most of the water supply of Metro Manila.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.