River in Cagayan Valley, Philippines Magat River Magat River mouth Show map of Luzon Magat River (Philippines) Show map of Philippines Native name Ilog ng Magat (Tagalog) Location Country Philippines Region Cagayan Valley Province Nueva Vizcaya Isabela Physical characteristics Source Conjunction of the Santa Fe and Marang Rivers • location Aritao, Nueva Vizcaya, Cordillera Central Mountains Mouth Confluence of Magat River-Cagayan River • location Gamu, Isabela • coordinates 17°02′27″N 121°49′43″E﻿ / ﻿17.040880°N 121.828583°E﻿ / 17.040880; 121.828583Coordinates: 17°02′27″N 121°49′43″E﻿ / ﻿17.040880°N 121.828583°E﻿ / 17.040880; 121.828583 • elevation 26 ft (7.9 m) Length 226 km (140 mi) Basin size 5,200 km2 (2,000 sq mi) Discharge • location Cagayan River • average 540 m3/s (19,000 cu ft/s) Basin features Progression Magat–Cagayan