Magat Dam in Ramon, Isabela used to be the largest dam in the Philippines back when it was built in 1983. The controversial San Roque Dam (featured previously) has since eclipsed it in both structural and reservoir size in 2004. Magat Dam generates 360 megawatts of electricity (with a water head of 81 meters high) and supplies irrigation water for approximately 85,000 hectares of farmland in Isabela and surrounding areas.
The dam was constructed at a cost of 6.5 billion pesos and consists of 3.1 kilometers of rock-fill construction. The dam and its watershed is managed by the National Irrigation Authority (NIA), while the National Power Corporation (NPC) managed the hydroelectric plant, before the plant was turned over to SN Aboitiz Power Inc. in April 2007 as part of the privatization of power plants under the Electric Power Industry Reform Act (EPIRA) of 2001.
Photo from the Department of Tourism webpage on Isabela.
Like the San Roque Dam, Magat Dam had its share of controversies, issues, and problems. For one, the reservoir inundated the traditional lands of the Ifugao tribes. Second, the useful lifespan of the dam was shortened from 50 years to around 35 years because of increased sedimentation in the reservoir (aggravated by the massive 1990 Luzon earthquake) and damage to the dam itself. Finally, Magat River, which is the river dammed, forms the boundary between the provinces of Ifugao and Isabela. Well, you can correctly guess that there’s a dispute between Ifugao and Isabela regarding with the dam: Ifugao is contesting the tax proceeds from the privatization of the hydroelectric plant and the compromise reached was that the two provinces would share equally in the tax revenue.
Magat Dam is also one of the prominent tourist spots in Isabela. The Magat Dam Tourism Complex promotes ecotourism with various watersports activities in the Magat Dam reservoir.
If you look at the Google Maps view of the dam, you can see the extent of the reservoir (4,450 hectares). And if you look about two kilometers downstream (east) from the dam, you can see Maris Dam, a subsidiary dam that helps regulate water level below the main dam for hydroelectric purposes. Why Maris? Well, Maris stands for Magat River Irrigation System.