[1] The 57,930-hectare (143,100-acre) Casecnan River Watershed Forest Reserve was established in August 1987 by virtue of Executive Order No.

[2] In April 2000, the forest reserve was enlarged to 88,846.80 hectares (219,545.2 acres) and was reclassified as a protected landscape area through Proclamation No.

It was established to protect the watershed around the Casecnan River, a tributary of the Rio Grande de Cagayan which flows through the mountains of central Sierra Madre, the Caraballo and Mamparang ranges.

[4] The river is used heavily for irrigation and serves much of the surrounding communities in Central Luzon and Cagayan Valley.

It also supplies hydroelectric power to the region, an additional 140 megawatts of power capacity to the Luzon grid through a tunnel and powerhouse built in 2001 from the diversion weirs in the Casecnan and Taan rivers in Nueva Vizcaya near Mount Guiwan to the Pantabangan Dam in Nueva Ecija.