US scientists raise La Niña alert

MANILA, Philippines — US climate scientists have raised the La Niña alert, bringing hope of rains coming to replenish the stock in Angat Dam and saving Metro Manila from a water crisis.

La Niña is a weather phenomenon that causes very dry conditions in the eastern Pacific — the western coast of the Americas — but very wet conditions in the west, including the areas around the Philippines.

It is the opposite of El Niño.

Angat stock falling

It is rainy season in the Philippines, but there has been little rain in recent weeks and the hot weather has been drying up Angat Dam in Bulacan province, which supplies the water needs of Metro Manila and surrounding provinces.

The weather bureau Philippine Atmospheric, Geological and Astronomical Services Administration (Pagasa) reported the Angat water level as 176.65 meters above sea level (masl) on Monday, lower than the dam’s minimum operating level of 180 masl.

The water level in the dam fell below 180 masl in September, and has been dropping every day for the last 23 days.

Monday’s advisory from the US Climate Prediction Center and the International Research Institute for Climate and Society eased fears of a water shortage in the capital if the Angat stock went on going down.

Using data for August, the two climate centers declared that La Niña conditions were prevailing and were 75 percent likely to continue through the Northern Hemisphere winter.

“In August, La Niña conditions were present, with below-average sea surface temperatures extending across the central and eastern equatorial Pacific Ocean,” they said.

In their previous advisory, which was based on July data, the two climate centers placed the probability of La Niña developing fully at 60 percent in the following three months. That means heavy rains may start coming in September, though Pagasa has been reporting only low pressure and monsoon effects in recent days.

Metro supply steady

When the water level at Angat falls below the rule curve, the first to get its supply reduced is the 218-megawatt Angat hydropower plant.

Next to go is the water supply for irrigating farms in the region.

For September, the National Water Resources Board has set the supply for use of the two Metro Manila water distributors—Maynilad Water Services Inc. and Manila Water Co. Inc. — at normal flow of 46 cubic meters per second.

Sevillo David Jr., the water board’s executive director, said Metro Manila’s water supply was being kept steady even if the water level at Angat had fallen below operating level as a preventive measure against the COVID-19 outbreak.