A top hydrologist from the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said Sunday a protocol covering the release of water from dams does exist.

Susan Espinueva, officer-in-charge (OIC) of PAGASA’s Hydrometeorology Division, made this clarification in reaction to charges that the absence of such a protocol aggravated the environmental damage wrought by typhoon “Pepeng” when it slammed into Central and Northern Luzon early this month.

Under the protocol, PAGASA provides state-owned National Power Corp. (Napocor) with all weather-related information like rainfall forecasts, Espinueva explained.

However, she admitted the bits of information do not include the volume of rainfall since PAGASA does not have the equipment to measure it.

Napocor uses the PAGASA forecast to assess the inflow of water into the dam, based on the actual level of rainfall and the expected rainfall. It then decides whether the gates or spillways will be closed or opened.

The Napocor then calls dam operators, like the San Roque Power Corp. (SRPC), and gives them instructions as to which gates should be opened and how much water must be released.

Espinueva said the San Roque dam has a top-of-gate elevation (or maximum water level) of 290 meters but the requirement of power generation is only at 280 meters.

“The 280- to 288-meter level is strictly flood control level,” she explained.

Espinueva’s explanation supported the statement of Tom Valdez, SRPC vice president for corporate social responsibility, that there is “no economic value for SRPC” to hold water above the 280-meter level of the dam.

SRPC owns the power station within the San Roque Multipurpose Project, while Napocor owns the dam and the dam’s related facilities, including the spillway.

“At the 280-meter mark, SRPC would have enough water to run the hydro-electric plant over the dry season up to the next rainy season,” Valdez said in a separate interview.

Valdez clarified that SRPC has no authority to open or close the spillway of the San Roque dam but added that “we (SRPC officials) did coordinate closely with flood-control experts from NPC,” adding that SRPC personnel carried out diligently the instructions of the NPC managers on releasing water from the dam.”

Espinueva added that the flood control purposes of the dam will be defeated if they automatically start releasing water when it reaches 280 meters.

“The level may be kept up to 288 meters if there is no rain expected and the downstream areas are already flooded,” she pointed out.

In the case of Pepeng, Espinueva said “there was no decision to release water because the dam could still hold it in."

“However, when Pepeng returned and brought more rain, a decision was made to release water to avoid breaching the dam,” she added.

As required by the protocol, authorities gave four hours' warning to local inhabitants before water was released. The four-hour notice was enough considering that it takes eight hours for water to reach inhabited areas from the dam.

Espinueva recalled that before the release of water during typhoon Pepeng, a meeting was held with local inhabitants through the provincial governor.