MANILA, Philippines—Did officials of the San Roque Dam follow their operations manual in regulating its water level amid the incessant rain and flooding triggered by Tropical Storm “Pepeng”?

The officials say they did. But based on the extent of the flooding that hit Pangasinan and the magnitude of the devastation, a Dagupan-based environmentalist doesn’t think so.

Nicanor Melecio, president of the NGO Pangasinan Institute for Land and Aquatic Research, said dam officials should have started releasing water at 500 cubic meters per second (cms) when the dam’s level had reached 280 meters above sea level (masl) as indicated in their basic operation rule.

The dam has a maximum elevation of 290 masl.

Under the rule, water release operates from “zero hour to 240 hours” when floods occur, said Melecio, a former member of the San Roque Dam multipartite monitoring team.

“You have 10 days to play with an incoming flood event by anticipating the water coming from the watershed,” he said.

In a privilege speech, Pangasinan Rep. Mark Cojuangco Tuesday called for an inquiry into the operations of the dam.

Cojuangco said that the “overloading” of downstream river systems beside the San Roque Dam had caused “tremendous devastation” in his province that could have been avoided had the dam operators followed a more “conservative and a cautious approach” in releasing excess water.

The San Roque Dam captures water released by the Ambuklao and Binga hydroelectric dams in the upstream Agno River in Benguet province.

Power needs vs people’s lives

When the San Roque Dam shifts to “flood mode,” or has reached the 280 masl mark, it should not be allowed to reach 290 masl, Melecio said.

“If you reach 290, it will be very difficult to control. So, even during the first 20 hours, you can start releasing [water]. You can start even up to 60 hours at 500 cms,” he said.

Melecio said water may be released up to 1,400 cms. “So, as you are releasing water, the dam’s water level that is supposed to be going up to 290 [masl] actually flattens,” he said.

But if the rains continue, and the dam’s water approaches the critical level of 290 masl, then there is no choice but to release more than 1,400 cms, he said.

“And so the question is: Do you have to wait for the water level to reach a very critical level so that you will release more than 1,400 cms? That’s the crux of the matter. How do you balance power needs as against people’s lives?” Melecio said.

Water releases

Based on SMS media advisories, Tom Valdez, a vice president of the San Roque Multipurpose Project (SRMP) that operates the facility owned by National Power Corp. (Napocor), said the dam first opened a spillway gate midnight of Oct. 7 when the water level was 287.65 masl.

Pepeng smacked Cagayan Valley on Oct. 3 and hovered west of northern Luzon for over a week before moving out of the country at the weekend.

The Provincial Disaster Coordinating Council (PDCC) in Pangasinan recorded the first water release at 12:03 a.m. on Oct. 7, when the water elevation at the San Roque Dam was 286.5 masl. The rate of water release was 181.5 cms, with one gate opened at a height of a meter.

Valdez’s advisory said that on the same day, the dam opened another gate and released excess water at 650 cms.

All 6 spillway gates open

The bulk of water release came on Oct. 8 when dam officials announced the opening of all its six spillway gates and released water at 2,500 cms.

The PDCC record showed that the dam, by 11 p.m. that day, was releasing water through its six gates at a rate of 3,600 cms. Water elevation at that time was 288.55 masl.

At 3 a.m. on Oct. 9, the dam was already releasing water at 5,072 cms. Water level at the reservoir was 289.05 masl.

The excess water overtopped dikes along the Agno River, eventually eroding them, causing a 7-kilometer breach in the dike along the Agno River at Barangay San Vicente in San Manuel and massive flooding in 38 towns and cities of Pangasinan.

The provincial government, farmers, business groups and concerned citizens said they would file a class suit against SRMP and Napocor for the destruction.

Followed diligently

Valdez in a statement said the dam operators coordinated and “carried out diligently” instructions by Napocor managers and experts on water releases.

“Napocor gave written instructions that were so specific that they included not only the time of the gate openings, but also the specific opening height of each gate to provide the release they required from the dam,” he said.

“Unfortunately, toward the end of the storm, the San Roque Dam no longer had the capacity to absorb the unprecedented level of rainwater dumped by (Pepeng).”

Operation rule vs gov’t policy

“There are two issues here,” Melecio said. “One is the basic operation rule of the San Roque Dam. The other is a local government policy, which takes precedence against utilities.”

He said it was “very clear in the dam’s basic operation rule that in the first 60 hours, water can already be released.”

“So, when the rains start coming in heavily, you beat the rainfall so that this rainfall will not raise the water level to 290 [masl],” Melecio said.

“We have a lot of robotic measurements, rain gauges in Mt. Sto. Tomas and Mt. Data along the Agno River. So, if you are a hydrologist, you should be able to interpret the rainfall and translate that,” he said.

“There should be a management review of the capability of dam controllers. Do they know what they are doing?” he said.

Massive spill over 10 hours

Cojuangco said his investigation showed that the dam released for more than 10 hours 5,700 cms into the floodwater control system or dikes of the Agno River.

When added to the normal 1,000-cubic-meter inflow from each of the three tributary rivers system, he said the dikes were overburdened with more than twice the floodwater control system’s capacity of 4,000 cubic meters per second.

“The water released grossly exceeded what the system was designed for so it’s no wonder the whole of Pangasinan was submerged in water,” said Cojuangco, who noted that the dam operators should have released water in smaller volumes ahead of the storm’s arrival.

‘Lame excuse’

Cojuangco dismissed as a “lame excuse” the dam operators blaming the weather bureau’s lack of equipment—Doppler radar—that would have advised them in advance of the amount of rainfall from an incoming typhoon or storm.

The militant group Bagong Alyansang Makabayan (Bayan) Tuesday said the long-term solution to the flooding in Pangasinan was the decommissioning of the San Roque Dam.

“It appears the interest of power generation won out over public safety,” Bayan secretary general Renato Reyes said in a statement. With a report from Gil C. Cabacungan Jr. and Leila B. Salaverria