Manila, May 21 -- Recent rains experienced in some parts of the country failed to increase the water levels in major reservoirs, and six dams are "critically low" as of Thursday, the head of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said.

"The lack of sufficient rainfall for the past weeks was the key factor in the decrease in the dams' water levels. The recent rainfall is localized due to thunderstorms," PAGASA Administrator Nathaniel Servando told the Philippine News Agency.

He confirmed that the warm and dry season has caused the decline in water levels.

"Rains are not enough to raise the water level in dams," he said.

Four dams have "critically low" levels, or below the rule curve. T...