By Jonathan L. Mayuga, May 10 2019; Business Mirror
https://businessmirror.com.ph/2019/05/10/despite-rains-dam-water-levels-still-below-normal/
Image Credit to Business Mirror
WATER levels at La Mesa Dam and Angat Dam remain below normal levels despite a spate of sporadic rains for the past few days.
As of 6 a.m. on May 9, the water level at La Mesa is 68.55 meters above sea level (asl). This is still below its normal level of 78 to 79 meters above sea level.
As of the same period, the water level at Angat is 174.78 meters. The minimum operating water level at Angat is 180 meters.
Angat Dam is the source of about 96 percent of water for Metro Manila’s close to 12 million population.
While the two private water contractors and agents of the Metropolitan Waterworks and Sewerage System (MWSS) are drawing water from Laguna de Bay, recent conditions such as the algae bloom—because of the warm weather—limit their water production capacities.
The Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said recent sporadic rains that occurred in the afternoon and in the evening is brought about by localized thunderstorms and should not be mistaken as the start of the rainy season.
Although sporadic rains are expected within the next two days, weather forecaster Jomaila Garrido said the rain can normally last up to an hour or two, not enough to raise the water level at Angat or La Mesa dam to ensure adequate raw water supply.
She explained that, while there are rains, these rains may not necessarily fall directly on the right watershed to increase existing water reserves at dams, such as La Mesa or Angat.
“These rains are brought about by localized thunderstorms and they can usually last one or two hours, not enough to increase the water level at La Mesa Dam or Angat,” Garrido said.
Garrido said the El Niño weather system continues to affect the Philippines, which means that the dry season may be extended up until June, or worse, July or August.
“We are still experiencing El Niño, that’s why we are not expecting enough amount of rains that can refill our dams,” she said in Filipino.
The water level at La Mesa dropped to a critical level in March this year, causing severe water service interruption that affected millions of customers within the East Zone Concession Area.
In the last two years, Manila Water, the concessionaire for the East Zone, was compelled to draw water from the La Mesa water reservoir to augment supply for its 6.8 million customers. Of the maximum daily water allocation for Metro Manila’s domestic water consumers, Manila Water is receiving 1,600 million liters per day of raw water from Angat, while Maynilad Water Services Inc.—the concessionaire for the West Zone—gets 2,400 MLD.
In a statement, Jeric Sevilla, Manila Water group head for Corporate Strategic Affairs, warned that the situation may actually get worse before it gets better.
“We welcome the rains that have been pouring over Metro Manila these past few days. But we cannot rest easy with it. First, the rains are still not sufficient to refill La Mesa Dam to its normal operating level of 78 to 79 meters. While the heavy rains last night added 10 centimeters to the level of La Mesa Dam, the level of 68.55 meters, as of 5 a.m., May 8, is still way below the critical level of 69 meters,” he said.
Sevilla said Manila Water needs continuous days of that much rain to refill La Mesa.
“Second, even if we are able to refill La Mesa, and we begin to draw water from it again to augment the still-deficient water supply, it is certain that we will encounter water-quality issues,” Sevilla added.
Since La Mesa is coming from subcritical levels, the soil that was previously submerged has since been exposed and may turn to mud when watered by rains, raising the level of the raw water’s turbidity, he explained. “We need to prepare for this eventuality because it takes time for water to return to normal turbidity levels,” Sevilla added.
Nonetheless, Sevilla assured customers within the East Zone concession area that, should this occur, Manila Water will continue to ensure that the water it distributes passes the stringent Philippine National Standard for Drinking Water (PNSDW), as set by the Department of Health (DOH).
Sevilla reported that Manila Water continues to make progress on its service recovery efforts. As of May 8, the company has achieved 98-percent water availability of at least eight hours at 7 psi, or at ground-floor level. It has also reached 72-percent, 24-hour water availability at 7 psi.
The company continues to work on various distribution solutions to address pocket areas of less than eight hours of supply. The Cardona Water Treatment Plant has been producing 50 million liters per day, and deep wells have augmented the Angat Water Supply with the production of 30 MLD. Cross-border flows are at 16 MLD.
