Supriya Ghosh (Editor)

Magat Dam

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Opening date

4,160 m (13,650 ft)

Maximum water depth
193 m (633 ft)


Construction began

Surface area
117 km (45 sq mi)

114 m

Type of dam
Embankment dam

Magat Dam, one of the largest dams in the Philippines located within the boundaries of Namillangan, Alfonso Lista, Ifugao, and Ramon, Isabela

Santiago City / Alfonso Lista, Ifugao / Ramon, Isabela

Binga Dam, Ambuklao Dam, Pantabangan Dam, Angat Dam, Ipo Dam

Magat dam isabela philippines

Magat Dam is a large Rock-fill dam in the island of Luzon in the Philippines. The dam is on the Magat River, a major tributary of Cagayan River. Construction of the dam started in 1975 and was completed in 1982. Magat Dam is one of the largest dams in the Philippines. It is a multi-purpose dam which is used primarily for irrigating about 85,000 hectares (210,000 acres) of agricultural lands, flood control, and power generation through the Magat hydroelectric power Plant.


Map of Magat Dam, Philippines

The water stored in the reservoir is enough to supply about two months of normal energy requirements.

The dam was constructed to last for 50 years but increased siltation and sedimentation in the reservoir, slash-and-burn farming, illegal logging and fish-caging resulted in the deterioration of the dam's watershed. The 1990 Luzon earthquake also contributed to the increased siltation in the Magat River system. Because of this, President Gloria Macapagal-Arroyo instructed various government agencies to create a rehabilitation plan to improve the lifespan of the dam system.

Magat dam hit by typhoon emong mpg


The construction and appurtenant structures was authorized by P.D. 693 signed on May 7, 1975 by the late President Ferdinand E. Marcos. The Magat Dam was constructed in 1978 and inaugurated by the Late Pres. Ferdinand E. Marcos on October 27, 1982 and started operations in 1983.

Implementation of this multipurpose project was based on the preliminary study conducted in 1973 by the National Irrigation Administration (NIA) with the assistance of the United States Bureau of Reclamation (USBR) and the United States Agency for International Development (USAID).

Subsequent detailed and extensive dam site investigation and engineering studies further confirmed the feasibility of what is now known as NIA's most daring infrastructure project and one of Asia's biggest dams today.

It was Southeast Asia's first large multipurpose dam. The dam is part of the Magat River Multipurpose Project (MRMP) which was financed by the World Bank and whose purpose is to improve on the existing Magat River Irrigation System (MARIS) and to triple the production of rice in the Cagayan River basin.

The project was jointly financed by the Philippine Government and the World Bank which extended a US$150M loan to finance the foreign exchange requirement. In addition, a US$9M loan from Bahrain was obtained for the purchase of other equipment for the diversion tunnels, soils laboratory and model testing. The total project cost is US$3.4B (yr. 1975).

The non-power components such as the dam, reservoir, and intake gates are owned, operated, and managed by the National Irrigation Administration (NIA). The hydroelectric plant was formerly owned by the National Power Corporation (NAPOCOR). Under the Electric Power Industry Reform Act of 2001 (Republic Act No. 9136), the Magat hydroelectric power plant underwent a privatization process. As a result, the plant's ownership and operation was turned over to SN Aboitiz Power-Magat, Inc. (SNAP-Magat), a joint venture of a local company, AboitizPower (AP), and a Norwegian firm SN Power in April 2007. SNAP won the bidding in 2006.


The Magat Dam is located at the boundaries of Santiago City and the municipalities of Alfonso Lista, Ifugao and Ramon,Isabela, approximately 350 kilometres (220 mi) north of Metro Manila.

Magat River

The Magat Dam is on the Magat River, which is the largest tributary of the Cagayan River on the island of Luzon. Cagayan is the longest river in the Philippines. The Magat River has an estimated yearly water discharge of 9,808 million cubic metres and has an approximate crest length of 4,160 metres (13,650 ft) with its headwaters in the province of Nueva Vizcaya and its confluence with the Cagayan River in the province of Isabela.

Magat 74High Dam

Height: 314 metres (1,030 ft)
Crest Length: 4,160 metres (13,650 ft)
Volume of Rocks & Earth Materials: 18 million cubic meters
Concrete = 1.00 million cubic meters


Length = 500 metres (1,600 ft)
Width = 164 metres (538 ft)
Discharge Cap.= 30,600 cubic meters
Radial Gates = 7 sets
Orifice Gates = 2 sets

Diversion Tunnels

Number: 2
Diameters: 2 metres (6.6 ft)
Ave.Length: 630 metres (2,070 ft)


Storage Capacity at Full Supply Level (FSL): 1.08 billion cubic meters
Elevation at FSL: 193 masl
Minimum Supply Level: 160 masl

Maximum Flood Level: 193 masl


Installed Capacity: 360 MegaWatts

Turbine: 4 Units, Francis Vertical Shaft

Generator: 4 Units x 90 MW, Vertical Synchronous


It is connected by an all-weather road to San Mateo-Santiago Road at Oscariz, Ramon, Isabela some 350 kilometres (220 mi) north of Metro Manila.

Magat Hydro

The Magat hydroelectric power plant is a four-unit powerhouse with an installed capacity of 360 megawatts. It is designed to accommodate two more units that will allow it to generate up to 540 megawatts. The hydroelectric plant is a peaking power plant, which means that it only operates when there is a high demand for electricity in the Luzon power grid, to which the plant is connected. It is capable of providing ancillary services for the stability of the grid.

SN Aboitiz Power-Magat, Inc. completed the half-life refurbishment of the Magat Hydroelectric Power Plant in 2014. Refurbishment began in 2009 and was completed in June 2014. Half-life refurbishment ensures that the power plant facility remains available throughout its life span.


Magat Dam Wikipedia