ILIGAN CITY, Philippines — Water levels at Lake Lanao in Lanao del Sur and Pulangi Dam in Bukidnon have fallen below their normal levels as rainfall remains limited, raising fresh concerns for Mindanao’s hydroelectric power supply.
As of noon on Tuesday, September 1, Lake Lanao stood at 700.7 meters, while the water level at Pulangi Dam was 283.9 meters, according to officials of the National Power Corporation’s Mindanao Generation Group cited by the Philippine Daily Inquirer.
The decline is being attributed primarily to a lack of rainfall, while sediment—or silt—at Pulangi Dam is compounding the situation.
Lake Lanao remains above its critical level
Despite the decline, Lake Lanao’s current elevation remains above the critical threshold cited by NPC-MGG plant manager Edgar Ramirez.
Ramirez said the critical water level for Lake Lanao is 698 meters, meaning Tuesday’s recorded level of 700.7 meters was still about 2.7 meters above that threshold.
That margin, however, makes continued monitoring important because Lake Lanao is a key component of Mindanao’s hydroelectric system.
The Agus hydroelectric plants draw from the Lake Lanao–Agus River system, with a series of plants extending from the lake toward Iligan City and Maria Cristina Falls.
The National Power Corporation says its Mindanao Generation Group manages the Agus and Pulangi power complexes, which play a major role in supplying electricity to Mindanao.
Pulangi Dam is already below its normal level
The situation at Pulangi Dam is also being closely watched.
NPC-MGG Pulangi plant manager Willy Alfeche said the dam’s water level had fallen to 283.9 meters, below its stated normal level of 285 meters.
Aside from reduced rainfall, Alfeche pointed to silt accumulation as another factor affecting the reservoir.
The long-term sedimentation issue at Pulangi IV is significant. A World Bank assessment previously noted that the reservoir’s original storage capacity had been substantially reduced by sedimentation, affecting the amount of water available for sustained hydroelectric generation.
NPC has also been undertaking dredging and other measures at the Pulangi IV hydroelectric facility as part of efforts to address reservoir conditions.
The timing is particularly important for Mindanao’s power supply
The falling water levels come as Mindanao’s electricity system is already operating with limited reserves.
The National Grid Corporation of the Philippines (NGCP) placed the Mindanao grid under yellow alert from 1 p.m. to 8 p.m. on September 1.
NGCP reported available capacity of approximately 2,555 megawatts (MW) against projected peak demand of 2,450 MW.
GMA News reported that 766.3 MW of capacity was unavailable because of forced outages and derated generating units. Twenty plants were on forced outage during August, while additional plants had been unavailable for longer periods.
The Philippine News Agency likewise reported that the Mindanao grid was placed under yellow alert amid multiple plant outages and reduced generating capacity.
A yellow alert does not automatically mean that consumers will experience blackouts. Rather, it means the operating margin is insufficient to meet the grid’s required contingency reserve.
But the combination of reduced generating capacity and declining water levels puts greater attention on Mindanao’s hydroelectric resources.
Hydro plants remain critical to Mindanao
The Agus and Pulangi hydroelectric complexes are among Mindanao’s most important power assets.
NPC has said the Agus-Pulangi system has a major role in supporting the island’s electricity requirements. In June, the state-owned power corporation announced efforts to restore generating units that had been offline because of planned, extended and emergency technical shutdowns.
By July, NPC reported that 17 of the 20 generating units in the Agus and Pulangi complexes were delivering a combined dependable capacity of about 796 MW, while restoration work continued on other units.
However, the current situation shows that restoring generating units is only part of the challenge.
Hydroelectric generation also depends heavily on the availability of water.
What happens if the dry conditions continue?
For now, officials have not said that Lake Lanao or Pulangi Dam has reached an emergency level.
Lake Lanao remains above the critical level cited by NPC, while Pulangi Dam is below its normal elevation but continues to operate.
The bigger concern is what could happen if below-normal rainfall persists.
Less water entering the reservoirs can eventually constrain hydroelectric generation, while sediment accumulation can further reduce effective storage capacity. At the same time, Mindanao’s electricity demand and the availability of other generating plants remain important factors in determining whether the grid has sufficient reserves.
Mindanao has already experienced repeated power-supply alerts in recent months. MindaNews reported in August that several major and smaller generating facilities had reduced output, including the Pulangi 4 hydroelectric plant, contributing to tight supply conditions.
For now, the numbers tell a story that authorities will be watching closely: Lake Lanao is still above its critical threshold, but Pulangi Dam is below normal, rainfall remains limited, and Mindanao’s power grid is operating with a narrow reserve margin.
The next major factor could be something the power sector cannot control—how much rain falls over Mindanao in the days and weeks ahead.
WWC ONE MEDIA MJE
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