Barangay Buyasan

Situated in San Mariano, Isabela, Barangay Buyasan is one of 36 barangays that make up the municipality within Cagayan Valley.

According to the 2020 Philippine census, Barangay Buyasan had a population of 814. This made it the 29th largest of 36 barangays in San Mariano by population, placing it among the smaller barangays of the municipality. Residents of Barangay Buyasan accounted for approximately 1.35% of the total population of San Mariano, which stood at 60,124 in the same census year.

The barangay recorded 722 residents in the 2015 intercensal count and 814 residents in the 2020 Census — a net change of +12.7%, consistent with a growing settlement. Barangay Buyasan is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

San Mariano is a municipality comprising 36 barangays, and serves as the governing unit directly responsible for local services in Barangay Buyasan, including public health, sanitation, peace and order, and civil registration. Within the wider province of Isabela, which contains 1,055 barangays across its component cities and municipalities, Barangay Buyasan ranks 761st by 2020 population. Isabela is classified as a 1st by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

The barangay's legislative and executive affairs are handled by a Punong Barangay and the Sangguniang Barangay, elected nationwide during the Barangay and SK Elections. The next BSKE is scheduled for Monday, November 2, 2026, following the synchronized election schedule set by COMELEC Resolution No. 11191.