The Agno River Basin


Posted at Oct 23 2009 03:25 PM | Updated as of Oct 25 2009 09:35 AM

This is the map of tributaries and flood-prone areas around the Agno River basin from Pagasa’s Flood Forecast Branch. The text below the map gives general information about the Agno River Basin and its environs.

Fast Facts:

  • Drainage area: 5,9252 sq. km
  • Third largest river in Luzon, fifth in the Philippines
  • Length of river system from source to mouth: 270 km (90 km of which runs through mountainous terrain and canyons)
  • Average elevation: 2,000 meters above sea level (masl)


  • Characterized by mountainous topography
  • Flood runoff: 6,654 million cubic meters (annual estimation)
  • Average annual rainfall:
    • 2,000 mm (in Tarlac portion)
    • 4,000 mm in upper reaches of Agno River
  • Flood target areas:
    • The entire Pangasinan Plain
    • Municipalities in Pangasinan:
      • Dagupan
      • Lingayen
      • Bugallon
      • Sta. Barbara
      • Bayambang
      • Rosales
    • Central part of Tarlac
    • Municipalities in Tarlac:
      • Gerona
      • Paniqui
      • Moncada

Connecting water ways and nearby mountain ranges

  • Source of water: the Cordillera Mountains
  • Mouth of the basin: Lingayen Gulf (Pangasinan)
  • Pangasinan plain
    • A vast alluvial fan and delta formed by the Agno River
    • Constitute the rice granary of Central Luzon
  • Principal tributaries:
    • Pila River
    • Camiling River (Tarlac)
    • Tarlac River – main branch of the Agno River
      • Source: Mount Pinatubo Volcano (elevation of 1,745 m)
    • Ambayoan River
  • Poponto Swamp (near Bayambang, Pangasinan)
    • Joins the Tarlac river and the Agno River
    • Area: 25 sq. km.
    • Retains flood waters from the Tarlac River

Source: Pagasa flood forecast branch