Magat Dam 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