ust os , ▁Bul ac an , ▁served ▁by ▁the ▁Ang at ▁River . ▁The ▁main ▁dam ▁is ▁about ▁ 1 8 ▁meters ▁above ▁sea ▁level . ▁Among ▁the ▁ 2 . 5 - meter ▁high , ▁six - span ▁dam ' s ▁main ▁features ▁are ▁easily ▁def lat able ▁and ▁infl atable ▁rub ber ▁body , ▁resistance ▁to ▁sed iment ation , ▁econom ical ▁and ▁having ▁auto - de fl ation ▁system . ▁ ▁History ▁▁ ▁Bu ilt ▁in ▁ 1 9 2 6 , ▁ 5 0 ▁kilom eters ▁up stream ▁from ▁the ▁B ust os ▁Dam ▁as ▁a ▁fixed ▁type ▁river ▁we ir ▁without ▁gates , ▁the ▁A ARD , ▁ ▁Ang at ▁After bay ▁Reg ulator ▁Dam ▁( comm only ▁known ▁as ▁B ust os ▁Dam ) ▁is ▁the ▁longest ▁rub ber ▁dam ▁in ▁Asia ▁at ▁ 7 9 ▁meters ▁and ▁the ▁second ▁largest ▁in ▁the ▁world . ▁It ▁has ▁coordinates ▁of ▁ 1 4 ° 5 7 ' 2 5 " N ▁ 1 2 0 ° 5 7 ' 1 5 " E ▁serving ▁nearby ▁cities : ▁Real , ▁Que zon , ▁Rod rig uez ▁( Mont al ban ), ▁R iz al , ▁Ant ip olo ▁City , ▁R iz al . ▁ ▁In ▁ 1 9 6 7 , ▁steel ▁sector ▁gates ▁were ▁installed ▁on ▁top ▁of ▁the ▁reg ulator ▁dam ▁for ▁the ▁purpose ▁of ▁generating ▁ir rig ation ▁water , ▁power ▁supply ▁and ▁domestic ▁water ▁supply . ▁ ▁Re h abil itation ▁ ▁With