Increased demand, over-reliance on Angat Dam blamed for water supply problem

Melissa Manansala, a resident of Barangay Plainview, has been using mineral water for cooking and dish washing since Friday, as there is not even a drop of water from the faucet.

"Ang hirap na, magastos pa," she says.

Manansala is just one of the 250,000 individuals considered as "worst-hit" customers of Manila Water as the east water concessionaire faces decreasing water supply.

These customers may need to keep on filling their pails and drums as the coming dry season may even trigger bigger supply problems.

For the past 50 years, Metro Manila has been relying heavily on the Angat Dam as its main source of water. According to MWSS, Metro Manila gets 96 percent of its water from the dam, 3 percent from Laguna Lake and only 1 percent from deep-well. 

MWSS Administrator Reynaldo Velasco says past administrations failed to foresee a surge in water demand and they now have to make up for lost time. 

"For the past 50 years walang na-develop na water source. Nag-rely tayo masyado sa Angat. MWSS is in the catch-up mode. We have to catch up with the requirements of Metro Manila," he says.

As of Monday, Angat Dam recorded normal water level with elevation of approximately 200 meters — still enough water for Metro Manila residents.

"Sa ngayon mga more than 200 meters ang elevation niyan, eh ang minimum operating level sa Angat is 180 meters so meron pa tayong mga more than 20 liters na normal na level," says National Water Resources Board (NWRB) Executive Director Sevillo David Jr.

Angat Dam releases water to Ipo Dam, which allocates 2,400 million liters of water per day to Maynilad and 1,600 million liters of water per day to Manila Water. Ipo Dam also releases water to La Mesa Dam, which serves as a reservoir where water concessionaires can draw water from.

With the  demand of Manila Water customers now at 1,740 million liters per day, or 240 million liters above its allocation of 1,600 million liters per day from Angat Dam, it needs to draw water from La Mesa Dam.

The problem now is La Mesa Dam has gone below its critical level of 69 meters after posting an elevation of 68.93 meters on Monday.

What's wrong with La Mesa?

La Mesa Dam on Monday posted its lowest level in 1998 at 68.75 meters and experts believe it's only a matter of time before it hits a new record low.

PAGASA hydrologist Richard Orendain says the water level at La Mesa Dam is going down twice as fast.

"Abrupt ang pagbaba ng La Mesa Dam," he says. "Usually ang pagbaba 6 to 7 centimeters per day. Ngayon 12 centimeters per day."

With little to no rain occurring at its watershed, La Mesa Dam may need additional water from Angat Dam.

David says NWRB is willing to allocate more water to increase the water level at La Mesa Dam but doubts about its capacity to hold back this action.

"Äng tanong po dun eh kung kakayanin pa ng sistema kasi yun sistema yun manggagaling for example ng Ipo. Si Ipo Dam kaya pa niya bang magkaroon ng karagdagang releases ng tubig and kasama rin po yun mga pipes nila. Kaya pa ba talagang i-absorb yun karagdagang tubig na puwedeng i-allocate kung sakaling magkaroon ng karagdagang tubig? May limitasyon din yun kapasidad ng mga sistema na ito para makapag-pondo at dumaloy yung tubig," he says.

Should Angat Dam release water in spite of the limited capacity of the conveyance system, water may not reach its intended recipient, the La Mesa Dam.

"Kung magdadagdag ka ng alokasyon tapos yung kapasidad ng mga dam mo hindi rin kaya, baka umapaw lang then mag-spill yan. Pag nag-spill ho kasi di rin makakarating sa mga sistema sa mga pang water supply. Kumbaga matatapon lang yan sa mga ilog," David explains.

The existing pipes that deliver water from Ipo Dam to La Mesa Dam would need an upgrade to withstand the increased flow of water should it draw more from Angat Dam.

"Aayusin natin yun portal na dinadaan ng tubig sa La Mesa para kung mayroon sumosobrang tubig sa Ipo, puwede natin i-divert yun sobrang tubig. Sa halip na itapon natin sa Bulacan itatapon natin sa La Mesa Dam," Velasco says.

He says previous MWSS administration did not have proper planning to address the crisis now. "Hindi nila masyado na-upgrade. Walang planning na eventually ganito ang requirement. Ngayon lang nakikita noong medyo nagigipit saka nag-iisip."

Who needs water?

Mandaluyong and Pasig are two of the worst-hit cities of water shortage in the past days as residents experienced little to no water.

Manila Water spokesperson Jeric Sevilla says the simultaneous drawing of water at odd hours made the water concessionaire unable to refill its tank.

In Mandaluyong, for example, Manila Water usually replenishes tanks between 12 a.m. to 4 a.m. when most people are asleep. However, residents collect water during these times. Even those areas which should not have been affected by the water interruption began drawing water, which eventually led to further supply disruption. 

"Kahit yun oras na yon napakataas ng demand so ang nangyari hindi natin napuno o na-refill yung reservoir kaya nabulaga yun mga tao na kinabukasan na wala silang tubig. Hanggang ngayon hindi pa nakaka-recover yun ating reservoir at mga pump station kung kaya may mga lugar na hindi pa rin nararating na tubig lalo na yun pinakamalayo at pinakamatataas na lugar," Sevilla explains.

What now?

To address the water supply problem, Maynilad has committed to give 50 million liters of water per day to Manila Water. MWSS is also allowing Manila Water to construct pumps all over Metro Manila, which could mean an additional 100 million liters per day of additional water.

Rizal area, which is being serviced by Manila Water, will have an additional supply of 50 million liters per day before the end of the month once the Cardona plant is operational. Within the year, an additional 50 million liters per day will be generated by the plant once it is 100 percent operational.

For its part, Manila Water will continue its rotational water supply to be able to share its available resources among its customers.

"Lahat ng lugar ay magkakaroon ng window kung saan meron siyang tubig para makapag-ipon siya at makapag-igib dahil wala tayong pinagkukunan ng dagdag na supply other than deep-wells," Sevilla says.

NWRB is managing its available resources to make sure there is water even during the dry season.

"Kailangan natin tignan yun pangangailangan natin sa mga susunod pang buwan lalo na ngayon panahon ng El Niño. So pag may El Niño kasi ang sinasabi mga hanggang Mayo ito o June so pag ganyan may mga posibleng yun mga pag-ulan hindi ganun kalaki," David says.

David says households will always be top priority when allocating water, but the board may need to manage its resources as temperature rises.

"Posibleng magkaroon tayo ng adjustment sa alokasyon sa puntong puwede tayong magbawas kung kinakailangan," David says. —KBK/KG, GMA News