MANILA, Philippines — Central Luzon farmers stand to suffer more than Metro Manila residents from the cutback in the water supply from Angat Dam, according to officials.
The National Water Resources Board (NWRB) began implementing Monday a cutback in the water supply for irrigation in the provinces of Bulacan and Pampanga, and domestic use in the metropolis to “stretch” the use of available water in the dam.
“With the cutback, what will be greatly affected is irrigation. That’s our immediate concern,” NWRB Executive Director Ramon Alikpala said.
But if worse comes to worst — if the dry spell continues and the water level in Angat further dips next month — both the farmers and the Metro Manila residents would bear the brunt, he said.
Alikpala said households in the metropolis should not be immediately concerned. “We haven’t reached a point where they should be concerned. Nevertheless, it shouldn’t also mean that we should not talk about conserving,” he said.
The NWRB reduced the water supply for 15,000 hectares of irrigated farms in Bulacan and Pampanga from 32 cubic meters per second to 25 cu m/sec through the National Irrigation Administration (NIA).
It also cut back the supply for 12 million residents in the metropolis from 43 cu m/sec to 41 cu m/sec through the Metropolitan Waterworks and Sewerage System (MWSS).
The cutback was prompted by the prolonged dry spell in Luzon that has lowered the water levels in several dams, cut down the power generated by hydroelectric plants, and caused brownouts.
San Roque Dam
In San Manuel town in Pangasinan province, the water level in the San Roque Dam’s reservoir has dropped to near its critical level, forcing engineers to conserve its supply.
Engineer Antonio Arnaldo of San Roque Power Corp.’s operations department said the company shut down its power generation facility for three days last week, from Friday to Sunday, to conserve water and collect rainwater.
The facility, however, started generating power Monday on a limited scale, he said.
The Laguna Lake’s water level has also declined.
The lake’s water elevation is lower than what is expected during the rainy season, according to the
Laguna Lake Development Authority (LLDA).
“It should be at 11.5 meters, but the rain is not continuous so the water is stagnant at 11 meters,” said Emil Hernandez, officer in charge of the LLDA’s Integrated Water Resources Division.
For the past few days, the eastern part of the Laguna province has experienced rains. But it was not enough to raise the water to the desired level, Hernandez said.
Laguna Lake, which is bounded by Manila, Rizal, Laguna and Cavite provinces, is the country’s largest brackish water lake with a surface area of 900 square kilometers.
LLDA estimates that there are more than 10 million people who depend on the lake’s ecosystem. People depend on it for food, irrigation, transportation, floodwater reservoir and industrial cooling, among others.
Many people living within the watershed depend on the lake for food. High commercial value fish are milk fish or bangus, tilapia, carp, Thai catfish or hito, ayungin, and biya. There are about 269 species of plants, fishes and various kinds of aquatic organisms.
Hernandez said the farming communities around the lake’s shoreline would be affected by the low water level. He noted that those who get their irrigation water from the lake would not be able to use the water because of its higher salinity content.
Most of the communities around the lake plant fast-growing vegetables like beans and root crops. Some also plant rice in the villages around the shoreline, according to Hernandez.
With the cutback of water supply from Angat Dam, there will be less water to irrigate farms in Bulacan and Pampanga, according to Jorge Estioco of the NWRB Angat Dam monitoring division.
“If there’s old standing water there, maybe it’s just adequate to flood the fields. If the standing water before was 4 cm, it would be lower in the coming days,” he said.
Farms nearly dry
After the two-month-long dry spell, some farms in San Ildefonso town in Bulacan were “nearly dry,” the NWRB said, citing NIA field reports.
To offset the cutback, the NIA could resort to motor-powered shallow tube wells to irrigate farms in Central Luzon, while the MWSS could conduct revalving or supply water to an area one at a time, according to NWRB.
But the worst is yet to come.
If the same weather persisted and the water level in Angat further dipped next month, the water supply for irrigation in Central Luzon would be cut off, and the water supply for residents in the metropolis would be further cut down.
“If this weather persists, it means the supply for irrigation would be stopped. Some 15,000 families are living off these farms. It will also mean the dam may not recover for the next cropping season, which means they might not be able to plant the next season,” Alikpala said.
Alikpala said this would lead to a further cutback in the amount of water being supplied to households in the metropolis.
“We’re now talking about water that will be rationed. If they get it 24 hours, they might get much less, or there may be days when they don’t get water at all,” he said.
The weather outlook for next month remains “grim,” with rainfall expected to be below normal, according to the Philippine Atmospheric, Geophysical and Astronomical Services Administration.
“But the possibility of this one-month rainfall outlook getting altered is always there,” PAGASA weather forecasting chief Nathaniel Cruz said.
There’s a typhoon hovering over the Pacific Ocean, but it’s not expected to enter the Philippine area of responsibility, he said.
Up by 5 cm
Downpours in Metro Manila over the weekend, triggered by the government’s cloud-seeding operations, increased the water level in Angat Dam by 5 cm, according to NWRB officials.
As of Monday morning, the water level in Angat Dam was 172.14 meters above sea level, less than 8 m below the normal operating level of 180 m.
If this further dropped to 170 m, a level at which the main turbines processing water for irrigation in Central Luzon could get severely damaged, this could force the government to cut off the water supply for irrigation.
“If the water level is below 180 m, this could bog down the turbines. There’s a certain limit for machines,” Estioco said.
“If we hit 170 m, the air gets mixed up with water. This causes friction and heat. That destroys the turbines. So if we hit 170 m, the turbines might be shut down,” he added.
Divert water from Ipo Dam
If that happens, finding an alternative source for irrigation in Central Luzon would be a “problem” for the government, Estioco said.
“But maybe, it’s possible to divert water from Ipo Dam,” he said.
Unlike the main turbines, the auxiliary turbines that process water for Metro Manila residents could still operate even if the water level is 160 m because they are built at a lower elevation, Estioco said.
“At 160 m, they can still be used,” he said.
Waiting for typhoons
At this time of the year, San Roque Power Corp. in Pangasinan should be discharging excess water from its dam to accommodate more rainwater brought about by typhoons or washed down from the Cordillera uplands.
With the limited water supply at the reservoir, the plant could generate electricity for only eight hours, at 95 megawatts (MW) per hour, Arnaldo said.
But how long the plant can generate power will depend on how much rain will fall in the coming days, he said.
The plant can generate power for 24 hours at 360 MW per hour if there is adequate water supply in its reservoir, he said.
“We are waiting for typhoons or even just heavy rains. [These are] most welcome now,” he said.
Water level in San Roque Dam was recorded at 226.47 meters at 8 a.m. Monday, more than a meter above its minimum level of 225 meters, due to rains in the area.
In Isabela, the cloud-seeding operation in the province on Saturday and Sunday did not help increase the water level in Magat Dam.
Saturnino Tenedero, dam instrumentation section chief, said the water level at the reservoir was 162.47 meters on Monday, down from the 163.5-meter elevation recorded on Saturday. With a report from Villamor Visaya Jr., Inquirer Northern Luzon